Category Archives: Software & Tools

Install Python 3 on Linux (Redhat, CentOS, Ubuntu)

Learn how to install python 3 on Linux like Redhat, centos, ubuntu, etc. Also, learn how to get rid of a few python related errors.

By default, all of the Linux distros have pre-installed Python. Most of it is Python 2.x. not Python 3.x. Many of nowadays tools, scripts, etc need Python version 3 (python3) for compiling.

In this article, we will see how to install python3 step by step on Linux like RHEL, centos, ubuntu, etc.

If your package manager repo does offer python3 for install then you can easily install it from there,. If not then follow this process to install from source code.

Let’s get into the step by step Python installation from its source code. As of today, the Latest Python release is 3.6.3 and it’s available here.

Step 1.

Download source code from the Python website on your server using tools like wget. We are using the latest release link here.

root@kerneltalks # wget https://www.python.org/ftp/python/3.6.3/Python-3.6.3.tar.xz
--2017-11-05 12:13:48--  https://www.python.org/ftp/python/3.6.3/Python-3.6.3.tar.xz
Resolving www.python.org (www.python.org)... 151.101.8.223, 2a04:4e42:2::223
Connecting to www.python.org (www.python.org)|151.101.8.223|:443... connected.
HTTP request sent, awaiting response... 200 OK
Length: 16974296 (16M) [application/octet-stream]
Saving to: ‘Python-3.6.3.tar.xz’

100%[==============================================================================================================================>] 16,974,296  4.21MB/s   in 4.0s

2017-11-05 12:13:52 (4.01 MB/s) - ‘Python-3.6.3.tar.xz’ saved [16974296/16974296]

Step 2.

Un-tar downloaded file and navigate to newly created Python directory Python-3.6.3. Also, make sure you have a GCC package installed on your system. If not install package gcc before proceeding to the next step.

root@kerneltalks # tar xf Python-3.6.3.tar.xz
root@kerneltalks # cd Python-3.6.3

Step 3.

Now its time to compile the source code. Execute configure script in Python-3.6.3 directory.

root@kerneltalks # ./configure
checking build system type... x86_64-pc-linux-gnu
checking host system type... x86_64-pc-linux-gnu
checking for python3.6... no
checking for python3... no
checking for python... python
checking for --enable-universalsdk... no
checking for --with-universal-archs... no
checking MACHDEP... linux
checking for --without-gcc... no
checking for --with-icc... no
checking for gcc... gcc
checking whether the C compiler works... yes
checking for C compiler default output file name... a.out
checking for suffix of executables...
checking whether we are cross compiling... no
checking for suffix of object files... o
checking whether we are using the GNU C compiler... yes
checking whether gcc accepts -g... yes
checking for gcc option to accept ISO C89... none needed
checking how to run the C preprocessor... gcc -E
checking for grep that handles long lines and -e... /bin/grep
checking for a sed that does not truncate output... /bin/sed
checking for --with-cxx-main=<compiler>... no
checking for g++... no
configure:

  By default, distutils will build C++ extension modules with "g++".
  If this is not intended, then set CXX on the configure command line.

checking for the platform triplet based on compiler characteristics... x86_64-linux-gnu
checking for -Wl,--no-as-needed... yes
checking for egrep... /bin/grep -E
checking for ANSI C header files... yes
checking for sys/types.h... yes
checking for sys/stat.h... yes
checking for stdlib.h... yes
checking for string.h... yes
checking for memory.h... yes
checking for strings.h... yes
checking for inttypes.h... yes
checking for stdint.h... yes
checking for unistd.h... yes
checking minix/config.h usability... no
checking minix/config.h presence... no
checking for minix/config.h... no
checking whether it is safe to define __EXTENSIONS__... yes
checking for the Android API level... not Android
checking for --with-suffix...
checking for case-insensitive build directory... no
checking LIBRARY... libpython$(VERSION)$(ABIFLAGS).a
checking LINKCC... $(PURIFY) $(MAINCC)
checking for GNU ld... yes
checking for inline... inline
checking for --enable-shared... no
checking for --enable-profiling... no
checking LDLIBRARY... libpython$(VERSION)$(ABIFLAGS).a
checking for ranlib... ranlib
checking for ar... ar
checking for readelf... readelf
checking for a BSD-compatible install... /bin/install -c
checking for a thread-safe mkdir -p... /bin/mkdir -p
checking for --with-pydebug... no
checking for --with-assertions... no
checking for --enable-optimizations... no
checking for --with-lto... no
checking target system type... x86_64-pc-linux-gnu
checking for -llvm-profdata... no
checking for llvm-profdata... ''
checking for -Wextra... yes
checking whether gcc accepts and needs -fno-strict-aliasing... no
checking if we can turn off gcc unused result warning... yes
checking if we can turn off gcc unused parameter warning... yes
checking if we can turn off gcc missing field initializers warning... yes
checking if we can turn on gcc mixed sign comparison warning... yes
checking if we can turn on gcc unreachable code warning... no
checking whether pthreads are available without options... no
checking whether gcc accepts -Kpthread... no
checking whether gcc accepts -Kthread... no
checking whether gcc accepts -pthread... yes
checking whether g++ also accepts flags for thread support... no
checking for ANSI C header files... (cached) yes
checking asm/types.h usability... yes
checking asm/types.h presence... yes
checking for asm/types.h... yes
checking conio.h usability... no
checking conio.h presence... no
checking for conio.h... no
checking direct.h usability... no
checking direct.h presence... no
checking for direct.h... no
checking dlfcn.h usability... yes
checking dlfcn.h presence... yes
checking for dlfcn.h... yes
checking errno.h usability... yes
checking errno.h presence... yes
checking for errno.h... yes
checking fcntl.h usability... yes
checking fcntl.h presence... yes
checking for fcntl.h... yes
checking grp.h usability... yes
checking grp.h presence... yes
checking for grp.h... yes
checking ieeefp.h usability... no
checking ieeefp.h presence... no
checking for ieeefp.h... no
checking io.h usability... no
checking io.h presence... no
checking for io.h... no
checking langinfo.h usability... yes
checking langinfo.h presence... yes
checking for langinfo.h... yes
checking libintl.h usability... yes
checking libintl.h presence... yes
checking for libintl.h... yes
checking process.h usability... no
checking process.h presence... no
checking for process.h... no
checking pthread.h usability... yes
checking pthread.h presence... yes
checking for pthread.h... yes
checking sched.h usability... yes
checking sched.h presence... yes
checking for sched.h... yes
checking shadow.h usability... yes
checking shadow.h presence... yes
checking for shadow.h... yes
checking signal.h usability... yes
checking signal.h presence... yes
checking for signal.h... yes
checking stropts.h usability... no
checking stropts.h presence... no
checking for stropts.h... no
checking termios.h usability... yes
checking termios.h presence... yes
checking for termios.h... yes
checking for unistd.h... (cached) yes
checking utime.h usability... yes
checking utime.h presence... yes
checking for utime.h... yes
checking poll.h usability... yes
checking poll.h presence... yes
checking for poll.h... yes
checking sys/devpoll.h usability... no
checking sys/devpoll.h presence... no
checking for sys/devpoll.h... no
checking sys/epoll.h usability... yes
checking sys/epoll.h presence... yes
checking for sys/epoll.h... yes
checking sys/poll.h usability... yes
checking sys/poll.h presence... yes
checking for sys/poll.h... yes
checking sys/audioio.h usability... no
checking sys/audioio.h presence... no
checking for sys/audioio.h... no
checking sys/xattr.h usability... yes
checking sys/xattr.h presence... yes
checking for sys/xattr.h... yes
checking sys/bsdtty.h usability... no
checking sys/bsdtty.h presence... no
checking for sys/bsdtty.h... no
checking sys/event.h usability... no
checking sys/event.h presence... no
checking for sys/event.h... no
checking sys/file.h usability... yes
checking sys/file.h presence... yes
checking for sys/file.h... yes
checking sys/ioctl.h usability... yes
checking sys/ioctl.h presence... yes
checking for sys/ioctl.h... yes
checking sys/kern_control.h usability... no
checking sys/kern_control.h presence... no
checking for sys/kern_control.h... no
checking sys/loadavg.h usability... no
checking sys/loadavg.h presence... no
checking for sys/loadavg.h... no
checking sys/lock.h usability... no
checking sys/lock.h presence... no
checking for sys/lock.h... no
checking sys/mkdev.h usability... no
checking sys/mkdev.h presence... no
checking for sys/mkdev.h... no
checking sys/modem.h usability... no
checking sys/modem.h presence... no
checking for sys/modem.h... no
checking sys/param.h usability... yes
checking sys/param.h presence... yes
checking for sys/param.h... yes
checking sys/random.h usability... no
checking sys/random.h presence... no
checking for sys/random.h... no
checking sys/select.h usability... yes
checking sys/select.h presence... yes
checking for sys/select.h... yes
checking sys/sendfile.h usability... yes
checking sys/sendfile.h presence... yes
checking for sys/sendfile.h... yes
checking sys/socket.h usability... yes
checking sys/socket.h presence... yes
checking for sys/socket.h... yes
checking sys/statvfs.h usability... yes
checking sys/statvfs.h presence... yes
checking for sys/statvfs.h... yes
checking for sys/stat.h... (cached) yes
checking sys/syscall.h usability... yes
checking sys/syscall.h presence... yes
checking for sys/syscall.h... yes
checking sys/sys_domain.h usability... no
checking sys/sys_domain.h presence... no
checking for sys/sys_domain.h... no
checking sys/termio.h usability... no
checking sys/termio.h presence... no
checking for sys/termio.h... no
checking sys/time.h usability... yes
checking sys/time.h presence... yes
checking for sys/time.h... yes
checking sys/times.h usability... yes
checking sys/times.h presence... yes
checking for sys/times.h... yes
checking for sys/types.h... (cached) yes
checking sys/uio.h usability... yes
checking sys/uio.h presence... yes
checking for sys/uio.h... yes
checking sys/un.h usability... yes
checking sys/un.h presence... yes
checking for sys/un.h... yes
checking sys/utsname.h usability... yes
checking sys/utsname.h presence... yes
checking for sys/utsname.h... yes
checking sys/wait.h usability... yes
checking sys/wait.h presence... yes
checking for sys/wait.h... yes
checking pty.h usability... yes
checking pty.h presence... yes
checking for pty.h... yes
checking libutil.h usability... no
checking libutil.h presence... no
checking for libutil.h... no
checking sys/resource.h usability... yes
checking sys/resource.h presence... yes
checking for sys/resource.h... yes
checking netpacket/packet.h usability... yes
checking netpacket/packet.h presence... yes
checking for netpacket/packet.h... yes
checking sysexits.h usability... yes
checking sysexits.h presence... yes
checking for sysexits.h... yes
checking bluetooth.h usability... no
checking bluetooth.h presence... no
checking for bluetooth.h... no
checking linux/tipc.h usability... yes
checking linux/tipc.h presence... yes
checking for linux/tipc.h... yes
checking linux/random.h usability... yes
checking linux/random.h presence... yes
checking for linux/random.h... yes
checking spawn.h usability... yes
checking spawn.h presence... yes
checking for spawn.h... yes
checking util.h usability... no
checking util.h presence... no
checking for util.h... no
checking alloca.h usability... yes
checking alloca.h presence... yes
checking for alloca.h... yes
checking endian.h usability... yes
checking endian.h presence... yes
checking for endian.h... yes
checking sys/endian.h usability... no
checking sys/endian.h presence... no
checking for sys/endian.h... no
checking sys/sysmacros.h usability... yes
checking sys/sysmacros.h presence... yes
checking for sys/sysmacros.h... yes
checking for dirent.h that defines DIR... yes
checking for library containing opendir... none required
checking whether sys/types.h defines makedev... yes
checking bluetooth/bluetooth.h usability... no
checking bluetooth/bluetooth.h presence... no
checking for bluetooth/bluetooth.h... no
checking for net/if.h... yes
checking for linux/netlink.h... yes
checking for linux/can.h... yes
checking for linux/can/raw.h... yes
checking for linux/can/bcm.h... yes
checking for clock_t in time.h... yes
checking for makedev... yes
checking for le64toh... yes
checking Solaris LFS bug... no
checking for mode_t... yes
checking for off_t... yes
checking for pid_t... yes
checking for size_t... yes
checking for uid_t in sys/types.h... yes
checking for ssize_t... yes
checking for __uint128_t... yes
checking size of int... 4
checking size of long... 8
checking size of long long... 8
checking size of void *... 8
checking size of short... 2
checking size of float... 4
checking size of double... 8
checking size of fpos_t... 16
checking size of size_t... 8
checking size of pid_t... 4
checking size of uintptr_t... 8
checking for long double support... yes
checking size of long double... 16
checking size of _Bool... 1
checking size of off_t... 8
checking whether to enable large file support... no
checking size of time_t... 8
checking for pthread_t... yes
checking size of pthread_t... 8
checking for --enable-framework... no
checking for dyld... no
checking the extension of shared libraries... .so
checking LDSHARED... $(CC) -shared
checking CCSHARED... -fPIC
checking LINKFORSHARED... -Xlinker -export-dynamic
checking CFLAGSFORSHARED...
checking SHLIBS... $(LIBS)
checking for sendfile in -lsendfile... no
checking for dlopen in -ldl... yes
checking for shl_load in -ldld... no
checking for library containing sem_init... -lpthread
checking for textdomain in -lintl... no
checking aligned memory access is required... no
checking for --with-hash-algorithm... default
checking for --with-address-sanitizer... no
checking for t_open in -lnsl... no
checking for socket in -lsocket... no
checking for --with-libs... no
checking for pkg-config... /bin/pkg-config
checking pkg-config is at least version 0.9.0... yes
checking for --with-system-expat... no
checking for --with-system-ffi... yes
checking for --with-system-libmpdec... no
checking for --enable-loadable-sqlite-extensions... no
checking for --with-tcltk-includes... default
checking for --with-tcltk-libs... default
checking for --with-dbmliborder...
checking for --with-threads... yes
checking if PTHREAD_SCOPE_SYSTEM is supported... yes
checking for pthread_sigmask... yes
checking for pthread_atfork... yes
checking if --enable-ipv6 is specified... yes
checking if RFC2553 API is available... yes
checking ipv6 stack type... linux-glibc
checking for CAN_RAW_FD_FRAMES... yes
checking for --with-doc-strings... yes
checking for --with-pymalloc... yes
checking for --with-valgrind... no
checking for --with-dtrace... no
checking for dlopen... yes
checking DYNLOADFILE... dynload_shlib.o
checking MACHDEP_OBJS... none
checking for alarm... yes
checking for accept4... yes
checking for setitimer... yes
checking for getitimer... yes
checking for bind_textdomain_codeset... yes
checking for chown... yes
checking for clock... yes
checking for confstr... yes
checking for ctermid... yes
checking for dup3... yes
checking for execv... yes
checking for faccessat... yes
checking for fchmod... yes
checking for fchmodat... yes
checking for fchown... yes
checking for fchownat... yes
checking for fexecve... yes
checking for fdopendir... yes
checking for fork... yes
checking for fpathconf... yes
checking for fstatat... yes
checking for ftime... yes
checking for ftruncate... yes
checking for futimesat... yes
checking for futimens... yes
checking for futimes... yes
checking for gai_strerror... yes
checking for getentropy... no
checking for getgrouplist... yes
checking for getgroups... yes
checking for getlogin... yes
checking for getloadavg... yes
checking for getpeername... yes
checking for getpgid... yes
checking for getpid... yes
checking for getpriority... yes
checking for getresuid... yes
checking for getresgid... yes
checking for getpwent... yes
checking for getspnam... yes
checking for getspent... yes
checking for getsid... yes
checking for getwd... yes
checking for initgroups... yes
checking for kill... yes
checking for killpg... yes
checking for lchmod... no
checking for lchown... yes
checking for linkat... yes
checking for lstat... yes
checking for lutimes... yes
checking for mmap... yes
checking for memrchr... yes
checking for mbrtowc... yes
checking for mkdirat... yes
checking for mkfifo... yes
checking for mkfifoat... yes
checking for mknod... yes
checking for mknodat... yes
checking for mktime... yes
checking for mremap... yes
checking for nice... yes
checking for openat... yes
checking for pathconf... yes
checking for pause... yes
checking for pipe2... yes
checking for plock... no
checking for poll... yes
checking for posix_fallocate... yes
checking for posix_fadvise... yes
checking for pread... yes
checking for pthread_init... no
checking for pthread_kill... yes
checking for putenv... yes
checking for pwrite... yes
checking for readlink... yes
checking for readlinkat... yes
checking for readv... yes
checking for realpath... yes
checking for renameat... yes
checking for select... yes
checking for sem_open... yes
checking for sem_timedwait... yes
checking for sem_getvalue... yes
checking for sem_unlink... yes
checking for sendfile... yes
checking for setegid... yes
checking for seteuid... yes
checking for setgid... yes
checking for sethostname... yes
checking for setlocale... yes
checking for setregid... yes
checking for setreuid... yes
checking for setresuid... yes
checking for setresgid... yes
checking for setsid... yes
checking for setpgid... yes
checking for setpgrp... yes
checking for setpriority... yes
checking for setuid... yes
checking for setvbuf... yes
checking for sched_get_priority_max... yes
checking for sched_setaffinity... yes
checking for sched_setscheduler... yes
checking for sched_setparam... yes
checking for sched_rr_get_interval... yes
checking for sigaction... yes
checking for sigaltstack... yes
checking for siginterrupt... yes
checking for sigpending... yes
checking for sigrelse... yes
checking for sigtimedwait... yes
checking for sigwait... yes
checking for sigwaitinfo... yes
checking for snprintf... yes
checking for strftime... yes
checking for strlcpy... no
checking for symlinkat... yes
checking for sync... yes
checking for sysconf... yes
checking for tcgetpgrp... yes
checking for tcsetpgrp... yes
checking for tempnam... yes
checking for timegm... yes
checking for times... yes
checking for tmpfile... yes
checking for tmpnam... yes
checking for tmpnam_r... yes
checking for truncate... yes
checking for uname... yes
checking for unlinkat... yes
checking for unsetenv... yes
checking for utimensat... yes
checking for utimes... yes
checking for waitid... yes
checking for waitpid... yes
checking for wait3... yes
checking for wait4... yes
checking for wcscoll... yes
checking for wcsftime... yes
checking for wcsxfrm... yes
checking for wmemcmp... yes
checking for writev... yes
checking for _getpty... no
checking whether dirfd is declared... yes
checking for chroot... yes
checking for link... yes
checking for symlink... yes
checking for fchdir... yes
checking for fsync... yes
checking for fdatasync... yes
checking for epoll... yes
checking for epoll_create1... yes
checking for kqueue... no
checking for prlimit... yes
checking for ctermid_r... no
checking for flock declaration... yes
checking for flock... yes
checking for getpagesize... yes
checking for broken unsetenv... no
checking for true... true
checking for inet_aton in -lc... yes
checking for chflags... no
checking for lchflags... no
checking for inflateCopy in -lz... no
checking for hstrerror... yes
checking for inet_aton... yes
checking for inet_pton... yes
checking for setgroups... yes
checking for openpty... no
checking for openpty in -lutil... yes
checking for forkpty... yes
checking for memmove... yes
checking for fseek64... no
checking for fseeko... yes
checking for fstatvfs... yes
checking for ftell64... no
checking for ftello... yes
checking for statvfs... yes
checking for dup2... yes
checking for strdup... yes
checking for getpgrp... yes
checking for setpgrp... (cached) yes
checking for gettimeofday... yes
checking for clock_gettime... yes
checking for clock_getres... yes
checking for clock_settime... yes
checking for major... yes
checking for if_nameindex... yes
checking for lockf... yes
checking for getaddrinfo... yes
checking getaddrinfo bug... no
checking for getnameinfo... yes
checking whether time.h and sys/time.h may both be included... yes
checking whether struct tm is in sys/time.h or time.h... time.h
checking for struct tm.tm_zone... yes
checking for struct stat.st_rdev... yes
checking for struct stat.st_blksize... yes
checking for struct stat.st_flags... no
checking for struct stat.st_gen... no
checking for struct stat.st_birthtime... no
checking for struct stat.st_blocks... yes
checking for struct passwd.pw_gecos... yes
checking for struct passwd.pw_passwd... yes
checking for time.h that defines altzone... no
checking whether sys/select.h and sys/time.h may both be included... yes
checking for addrinfo... yes
checking for sockaddr_storage... yes
checking for sockaddr_alg... yes
checking whether char is unsigned... no
checking for an ANSI C-conforming const... yes
checking for working volatile... yes
checking for working signed char... yes
checking for prototypes... yes
checking for variable length prototypes and stdarg.h... yes
checking for socketpair... yes
checking if sockaddr has sa_len member... no
checking for gethostbyname_r... yes
checking gethostbyname_r with 6 args... yes
checking for __fpu_control... yes
checking for --with-fpectl... no
checking for --with-libm=STRING... default LIBM="-lm"
checking for --with-libc=STRING... default LIBC=""
checking for x64 gcc inline assembler... yes
checking whether C doubles are little-endian IEEE 754 binary64... yes
checking whether C doubles are big-endian IEEE 754 binary64... no
checking whether C doubles are ARM mixed-endian IEEE 754 binary64... no
checking whether we can use gcc inline assembler to get and set x87 control word... yes
checking whether we can use gcc inline assembler to get and set mc68881 fpcr... no
checking for x87-style double rounding... no
checking for acosh... yes
checking for asinh... yes
checking for atanh... yes
checking for copysign... yes
checking for erf... yes
checking for erfc... yes
checking for expm1... yes
checking for finite... yes
checking for gamma... yes
checking for hypot... yes
checking for lgamma... yes
checking for log1p... yes
checking for log2... yes
checking for round... yes
checking for tgamma... yes
checking whether isinf is declared... yes
checking whether isnan is declared... yes
checking whether isfinite is declared... yes
checking whether tanh preserves the sign of zero... yes
checking whether log1p drops the sign of negative zero... no
checking whether POSIX semaphores are enabled... yes
checking for broken sem_getvalue... no
checking whether RTLD_LAZY is declared... yes
checking whether RTLD_NOW is declared... yes
checking whether RTLD_GLOBAL is declared... yes
checking whether RTLD_LOCAL is declared... yes
checking whether RTLD_NODELETE is declared... yes
checking whether RTLD_NOLOAD is declared... yes
checking whether RTLD_DEEPBIND is declared... yes
checking digit size for Python's longs... no value specified
checking wchar.h usability... yes
checking wchar.h presence... yes
checking for wchar.h... yes
checking size of wchar_t... 4
checking for UCS-4 tcl... no
checking whether wchar_t is signed... yes
no usable wchar_t found
checking whether byte ordering is bigendian... no
checking ABIFLAGS... m
checking SOABI... cpython-36m-x86_64-linux-gnu
checking LDVERSION... $(VERSION)$(ABIFLAGS)
checking whether right shift extends the sign bit... yes
checking for getc_unlocked() and friends... yes
checking how to link readline libs... none
checking for rl_callback_handler_install in -lreadline... no
checking for rl_pre_input_hook in -lreadline... no
checking for rl_completion_display_matches_hook in -lreadline... no
checking for rl_resize_terminal in -lreadline... no
checking for rl_completion_matches in -lreadline... no
checking for append_history in -lreadline... no
checking for broken nice()... no
checking for broken poll()... no
checking for struct tm.tm_zone... (cached) yes
checking for working tzset()... yes
checking for tv_nsec in struct stat... yes
checking for tv_nsec2 in struct stat... no
checking curses.h usability... no
checking curses.h presence... no
checking for curses.h... no
checking ncurses.h usability... no
checking ncurses.h presence... no
checking for ncurses.h... no
checking for term.h... no
checking whether mvwdelch is an expression... no
checking whether WINDOW has _flags... no
checking for is_term_resized... no
checking for resize_term... no
checking for resizeterm... no
configure: checking for device files
checking for /dev/ptmx... yes
checking for /dev/ptc... no
checking for %zd printf() format support... yes
checking for socklen_t... yes
checking for broken mbstowcs... no
checking for --with-computed-gotos... no value specified
checking whether gcc -pthread supports computed gotos... yes
checking for build directories... done
checking for -O2... yes
checking for glibc _FORTIFY_SOURCE/memmove bug... no
checking for gcc ipa-pure-const bug... no
checking for stdatomic.h... no
checking for GCC >= 4.7 __atomic builtins... yes
checking for ensurepip... upgrade
checking if the dirent structure of a d_type field... yes
checking for the Linux getrandom() syscall... yes
checking for the getrandom() function... no
configure: creating ./config.status
config.status: creating Makefile.pre
config.status: creating Modules/Setup.config
config.status: creating Misc/python.pc
config.status: creating Misc/python-config.sh
config.status: creating Modules/ld_so_aix
config.status: creating pyconfig.h
creating Modules/Setup
creating Modules/Setup.local
creating Makefile


If you want a release build with all stable optimizations active (PGO, etc),
please run ./configure --enable-optimizations

Step 4.

Now run make followed by make install to complete the installation. Both commands output is not given here since its pretty long.

root@kerneltalks # make
root@kerneltalks # make install

Step 5.

Check Python installed version from Python prompt.

root@kerneltalks # python3
Python 3.6.3 (default, Nov  5 2017, 12:28:06)
[GCC 4.8.5 20150623 (Red Hat 4.8.5-16)] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>>

You can see in the above output Python 3.6.3 shows we have installed python v3 successfully.

Troubleshooting Python issues

When using or compiling Python programs you might run into below errors. I have listed their solutions for your quick reference.

Error : ImportError: No module named 'zlib'

Solution: Install zlib-devel (zlib development tools) package and re-install python

Error : ImportError: cannot import name 'HTTPSConnection'

Solution: Install OpenSSL-devel (Open SSL development tools) package and re-install python

Error : zipimport.ZipImportError: can't decompress data; zlib not available

Solution: This error is seen during Python installation if zlib is not installed on the server. Install zlib package

Get your Linux ISO download from these URLs

2 Replies

List of all Linux ISO download links. The latest and old releases of various Linux distro can be downloaded using links listed on this page.

Many times I come across questions from people or readers that where I can download RHEL iso? Where to download Ubuntu Linux? etc. Actually these download links are very easy to get from Google but still I thought of publishing them all in one place.

In this post, I will list all possible Linux download websites. Please note that all Linux distro’s server copy is taken into consideration for choosing download links.

Red Hat Enterprise Linux RHEL latest release download link. Old releases download link. You have to create a developer account here to get your ISO copy.
CentOS Linux latest release download link. Old releases download link. No signup needed.
Fedora Linux download link. No signup needed.
Debian Linux download link. There are country wise FTP mirrors listed. Choose your nearest one and download it.
Ubuntu Linux Latest release download link. Old releases download link
Arch Linux download link. Country-wise HTTP mirror list.
Kali Linux latest release download link. Old releases download link
Linux mint latest release download link. Old releases download link
OpenSUSE Linux latest release download link
SUSE Linux 60 days trial download link
Open Mandriva Linux download link
Kubuntu Linux download link
Bodhi Linux download link
Gentoo Linux download link

The list will go on since Linux is open source and there are many distros floating around the internet! Report broken links and any additions in the comments below.

Nginx installation on Linux server

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Step by step Nginx installation on YUM or APT based Linux servers. Know about configuration files, log files, and directory listing in Nginx.

Nginx is a popular web server and preferred over Apache. Many websites and blogs today run on Nginx webserver. In this article, we are going to see how to install Nginx in Linux.

Nginx Installation

Nginx is available for install in EPEL repositories for YUM based Linux systems and in default repositories of APT (Debian) based systems. Depending on your system type install the Nginx package. Sample outputs below :

# yum install nginx
Loaded plugins: amazon-id, rhui-lb, search-disabled-repos, security
Setting up Install Process
epel/metalink                                                                                                                         | 4.4 kB     00:00
epel                                                                                                                                  | 4.3 kB     00:00
https://mirrors.tuna.tsinghua.edu.cn/epel/6/x86_64/repodata/repomd.xml: [Errno -1] repomd.xml does not match metalink for epel
Trying other mirror.
epel                                                                                                                                  | 4.3 kB     00:00
rhui-REGION-client-config-server-6                                                                                                    | 2.9 kB     00:00
rhui-REGION-rhel-server-releases                                                                                                      | 3.5 kB     00:00
rhui-REGION-rhel-server-releases-optional                                                                                             | 3.5 kB     00:00
rhui-REGION-rhel-server-rh-common                                                                                                     | 3.8 kB     00:00
Resolving Dependencies
--> Running transaction check
---> Package nginx.x86_64 0:1.10.2-1.el6 will be installed
--> Processing Dependency: nginx-filesystem = 1.10.2-1.el6 for package: nginx-1.10.2-1.el6.x86_64
--> Processing Dependency: nginx-all-modules = 1.10.2-1.el6 for package: nginx-1.10.2-1.el6.x86_64
--> Processing Dependency: nginx-filesystem for package: nginx-1.10.2-1.el6.x86_64
--> Running transaction check
---> Package nginx-all-modules.noarch 0:1.10.2-1.el6 will be installed
--> Processing Dependency: nginx-mod-stream = 1.10.2-1.el6 for package: nginx-all-modules-1.10.2-1.el6.noarch
--> Processing Dependency: nginx-mod-mail = 1.10.2-1.el6 for package: nginx-all-modules-1.10.2-1.el6.noarch
--> Processing Dependency: nginx-mod-http-xslt-filter = 1.10.2-1.el6 for package: nginx-all-modules-1.10.2-1.el6.noarch
--> Processing Dependency: nginx-mod-http-perl = 1.10.2-1.el6 for package: nginx-all-modules-1.10.2-1.el6.noarch
--> Processing Dependency: nginx-mod-http-image-filter = 1.10.2-1.el6 for package: nginx-all-modules-1.10.2-1.el6.noarch
--> Processing Dependency: nginx-mod-http-geoip = 1.10.2-1.el6 for package: nginx-all-modules-1.10.2-1.el6.noarch
---> Package nginx-filesystem.noarch 0:1.10.2-1.el6 will be installed
--> Running transaction check
---> Package nginx-mod-http-geoip.x86_64 0:1.10.2-1.el6 will be installed
--> Processing Dependency: GeoIP for package: nginx-mod-http-geoip-1.10.2-1.el6.x86_64
--> Processing Dependency: libGeoIP.so.1()(64bit) for package: nginx-mod-http-geoip-1.10.2-1.el6.x86_64
---> Package nginx-mod-http-image-filter.x86_64 0:1.10.2-1.el6 will be installed
--> Processing Dependency: gd for package: nginx-mod-http-image-filter-1.10.2-1.el6.x86_64
--> Processing Dependency: libgd.so.2()(64bit) for package: nginx-mod-http-image-filter-1.10.2-1.el6.x86_64
---> Package nginx-mod-http-perl.x86_64 0:1.10.2-1.el6 will be installed
---> Package nginx-mod-http-xslt-filter.x86_64 0:1.10.2-1.el6 will be installed
---> Package nginx-mod-mail.x86_64 0:1.10.2-1.el6 will be installed
---> Package nginx-mod-stream.x86_64 0:1.10.2-1.el6 will be installed
--> Running transaction check
---> Package GeoIP.x86_64 0:1.6.5-1.el6 will be installed
--> Processing Dependency: geoipupdate for package: GeoIP-1.6.5-1.el6.x86_64
--> Processing Dependency: GeoIP-data for package: GeoIP-1.6.5-1.el6.x86_64
---> Package gd.x86_64 0:2.0.35-11.el6 will be installed
--> Processing Dependency: libXpm.so.4()(64bit) for package: gd-2.0.35-11.el6.x86_64
--> Running transaction check
---> Package GeoIP-GeoLite-data.noarch 0:2017.01-1.el6 will be installed
--> Processing Dependency: GeoIP-GeoLite-data-extra = 2017.01-1.el6 for package: GeoIP-GeoLite-data-2017.01-1.el6.noarch
---> Package geoipupdate.x86_64 0:2.2.1-2.el6 will be installed
---> Package libXpm.x86_64 0:3.5.10-2.el6 will be installed
--> Running transaction check
---> Package GeoIP-GeoLite-data-extra.noarch 0:2017.01-1.el6 will be installed
--> Finished Dependency Resolution

Dependencies Resolved

=============================================================================================================================================================
 Package                                      Arch                    Version                        Repository                                         Size
=============================================================================================================================================================
Installing:
 nginx                                        x86_64                  1.10.2-1.el6                   epel                                              462 k
Installing for dependencies:
 GeoIP                                        x86_64                  1.6.5-1.el6                    epel                                              113 k
 GeoIP-GeoLite-data                           noarch                  2017.01-1.el6                  epel                                              468 k
 GeoIP-GeoLite-data-extra                     noarch                  2017.01-1.el6                  epel                                               23 M
 gd                                           x86_64                  2.0.35-11.el6                  rhui-REGION-rhel-server-releases                  142 k
 geoipupdate                                  x86_64                  2.2.1-2.el6                    epel                                               28 k
 libXpm                                       x86_64                  3.5.10-2.el6                   rhui-REGION-rhel-server-releases                   51 k
 nginx-all-modules                            noarch                  1.10.2-1.el6                   epel                                              7.7 k
 nginx-filesystem                             noarch                  1.10.2-1.el6                   epel                                              8.5 k
 nginx-mod-http-geoip                         x86_64                  1.10.2-1.el6                   epel                                               14 k
 nginx-mod-http-image-filter                  x86_64                  1.10.2-1.el6                   epel                                               16 k
 nginx-mod-http-perl                          x86_64                  1.10.2-1.el6                   epel                                               26 k
 nginx-mod-http-xslt-filter                   x86_64                  1.10.2-1.el6                   epel                                               16 k
 nginx-mod-mail                               x86_64                  1.10.2-1.el6                   epel                                               43 k
 nginx-mod-stream                             x86_64                  1.10.2-1.el6                   epel                                               36 k

Transaction Summary
=============================================================================================================================================================
Install      15 Package(s)

Total download size: 24 M
Installed size: 49 M
Is this ok [y/N]: y
Downloading Packages:
(1/15): GeoIP-1.6.5-1.el6.x86_64.rpm                                                                                                  | 113 kB     00:00
(2/15): GeoIP-GeoLite-data-2017.01-1.el6.noarch.rpm                                                                                   | 468 kB     00:00
(3/15): GeoIP-GeoLite-data-extra-2017.01-1.el6.noarch.rpm                                                                             |  23 MB     00:01
(4/15): gd-2.0.35-11.el6.x86_64.rpm                                                                                                   | 142 kB     00:00
(5/15): geoipupdate-2.2.1-2.el6.x86_64.rpm                                                                                            |  28 kB     00:00
(6/15): libXpm-3.5.10-2.el6.x86_64.rpm                                                                                                |  51 kB     00:00
(7/15): nginx-1.10.2-1.el6.x86_64.rpm                                                                                                 | 462 kB     00:00
(8/15): nginx-all-modules-1.10.2-1.el6.noarch.rpm                                                                                     | 7.7 kB     00:00
(9/15): nginx-filesystem-1.10.2-1.el6.noarch.rpm                                                                                      | 8.5 kB     00:00
(10/15): nginx-mod-http-geoip-1.10.2-1.el6.x86_64.rpm                                                                                 |  14 kB     00:00
(11/15): nginx-mod-http-image-filter-1.10.2-1.el6.x86_64.rpm                                                                          |  16 kB     00:00
(12/15): nginx-mod-http-perl-1.10.2-1.el6.x86_64.rpm                                                                                  |  26 kB     00:00
(13/15): nginx-mod-http-xslt-filter-1.10.2-1.el6.x86_64.rpm                                                                           |  16 kB     00:00
(14/15): nginx-mod-mail-1.10.2-1.el6.x86_64.rpm                                                                                       |  43 kB     00:00
(15/15): nginx-mod-stream-1.10.2-1.el6.x86_64.rpm                                                                                     |  36 kB     00:00
-------------------------------------------------------------------------------------------------------------------------------------------------------------
Total                                                                                                                        6.1 MB/s |  24 MB     00:03
Running rpm_check_debug
Running Transaction Test
Transaction Test Succeeded
Running Transaction
  Installing : GeoIP-GeoLite-data-extra-2017.01-1.el6.noarch                                                                                            1/15
  Installing : GeoIP-GeoLite-data-2017.01-1.el6.noarch                                                                                                  2/15
  Installing : nginx-filesystem-1.10.2-1.el6.noarch                                                                                                     3/15
  Installing : geoipupdate-2.2.1-2.el6.x86_64                                                                                                           4/15
  Installing : GeoIP-1.6.5-1.el6.x86_64                                                                                                                 5/15
  Installing : libXpm-3.5.10-2.el6.x86_64                                                                                                               6/15
  Installing : gd-2.0.35-11.el6.x86_64                                                                                                                  7/15
  Installing : nginx-mod-http-geoip-1.10.2-1.el6.x86_64                                                                                                 8/15
  Installing : nginx-mod-stream-1.10.2-1.el6.x86_64                                                                                                     9/15
  Installing : nginx-mod-http-perl-1.10.2-1.el6.x86_64                                                                                                 10/15
  Installing : nginx-mod-http-image-filter-1.10.2-1.el6.x86_64                                                                                         11/15
  Installing : nginx-mod-http-xslt-filter-1.10.2-1.el6.x86_64                                                                                          12/15
  Installing : nginx-1.10.2-1.el6.x86_64                                                                                                               13/15
  Installing : nginx-mod-mail-1.10.2-1.el6.x86_64                                                                                                      14/15
  Installing : nginx-all-modules-1.10.2-1.el6.noarch                                                                                                   15/15
  Verifying  : nginx-mod-mail-1.10.2-1.el6.x86_64                                                                                                       1/15
  Verifying  : GeoIP-1.6.5-1.el6.x86_64                                                                                                                 2/15
  Verifying  : nginx-mod-http-geoip-1.10.2-1.el6.x86_64                                                                                                 3/15
  Verifying  : libXpm-3.5.10-2.el6.x86_64                                                                                                               4/15
  Verifying  : nginx-mod-stream-1.10.2-1.el6.x86_64                                                                                                     5/15
  Verifying  : nginx-all-modules-1.10.2-1.el6.noarch                                                                                                    6/15
  Verifying  : GeoIP-GeoLite-data-2017.01-1.el6.noarch                                                                                                  7/15
  Verifying  : nginx-mod-http-perl-1.10.2-1.el6.x86_64                                                                                                  8/15
  Verifying  : nginx-mod-http-image-filter-1.10.2-1.el6.x86_64                                                                                          9/15
  Verifying  : nginx-1.10.2-1.el6.x86_64                                                                                                               10/15
  Verifying  : geoipupdate-2.2.1-2.el6.x86_64                                                                                                          11/15
  Verifying  : GeoIP-GeoLite-data-extra-2017.01-1.el6.noarch                                                                                           12/15
  Verifying  : nginx-filesystem-1.10.2-1.el6.noarch                                                                                                    13/15
  Verifying  : gd-2.0.35-11.el6.x86_64                                                                                                                 14/15
  Verifying  : nginx-mod-http-xslt-filter-1.10.2-1.el6.x86_64                                                                                          15/15

Installed:
  nginx.x86_64 0:1.10.2-1.el6

Dependency Installed:
  GeoIP.x86_64 0:1.6.5-1.el6                             GeoIP-GeoLite-data.noarch 0:2017.01-1.el6      GeoIP-GeoLite-data-extra.noarch 0:2017.01-1.el6
  gd.x86_64 0:2.0.35-11.el6                              geoipupdate.x86_64 0:2.2.1-2.el6               libXpm.x86_64 0:3.5.10-2.el6
  nginx-all-modules.noarch 0:1.10.2-1.el6                nginx-filesystem.noarch 0:1.10.2-1.el6         nginx-mod-http-geoip.x86_64 0:1.10.2-1.el6
  nginx-mod-http-image-filter.x86_64 0:1.10.2-1.el6      nginx-mod-http-perl.x86_64 0:1.10.2-1.el6      nginx-mod-http-xslt-filter.x86_64 0:1.10.2-1.el6
  nginx-mod-mail.x86_64 0:1.10.2-1.el6                   nginx-mod-stream.x86_64 0:1.10.2-1.el6

Complete!

# apt-get install nginx
Reading package lists... Done
Building dependency tree
Reading state information... Done
The following packages were automatically installed and are no longer required:
  linux-headers-4.4.0-59 linux-headers-4.4.0-59-generic linux-headers-4.4.0-66 linux-headers-4.4.0-66-generic linux-image-4.4.0-59-generic
  linux-image-4.4.0-66-generic
Use 'apt autoremove' to remove them.
The following additional packages will be installed:
  fontconfig-config fonts-dejavu-core libfontconfig1 libgd3 libjbig0 libjpeg-turbo8 libjpeg8 libtiff5 libvpx3 libxpm4 libxslt1.1 nginx-common nginx-core
Suggested packages:
  libgd-tools fcgiwrap nginx-doc ssl-cert
The following NEW packages will be installed:
  fontconfig-config fonts-dejavu-core libfontconfig1 libgd3 libjbig0 libjpeg-turbo8 libjpeg8 libtiff5 libvpx3 libxpm4 libxslt1.1 nginx nginx-common
  nginx-core
0 upgraded, 14 newly installed, 0 to remove and 64 not upgraded.
Need to get 2,999 kB of archives.
After this operation, 9,781 kB of additional disk space will be used.
Do you want to continue? [Y/n] y
Get:1 http://ap-south-1.ec2.archive.ubuntu.com/ubuntu xenial/main amd64 libjpeg-turbo8 amd64 1.4.2-0ubuntu3 [111 kB]
Get:2 http://ap-south-1.ec2.archive.ubuntu.com/ubuntu xenial/main amd64 libjbig0 amd64 2.1-3.1 [26.6 kB]
Get:3 http://ap-south-1.ec2.archive.ubuntu.com/ubuntu xenial/main amd64 fonts-dejavu-core all 2.35-1 [1,039 kB]
Get:4 http://ap-south-1.ec2.archive.ubuntu.com/ubuntu xenial-updates/main amd64 fontconfig-config all 2.11.94-0ubuntu1.1 [49.9 kB]
Get:5 http://ap-south-1.ec2.archive.ubuntu.com/ubuntu xenial-updates/main amd64 libfontconfig1 amd64 2.11.94-0ubuntu1.1 [131 kB]
Get:6 http://ap-south-1.ec2.archive.ubuntu.com/ubuntu xenial/main amd64 libjpeg8 amd64 8c-2ubuntu8 [2,194 B]
Get:7 http://ap-south-1.ec2.archive.ubuntu.com/ubuntu xenial-updates/main amd64 libtiff5 amd64 4.0.6-1ubuntu0.1 [146 kB]
Get:8 http://ap-south-1.ec2.archive.ubuntu.com/ubuntu xenial/main amd64 libvpx3 amd64 1.5.0-2ubuntu1 [732 kB]
Get:9 http://ap-south-1.ec2.archive.ubuntu.com/ubuntu xenial-updates/main amd64 libxpm4 amd64 1:3.5.11-1ubuntu0.16.04.1 [33.8 kB]
Get:10 http://ap-south-1.ec2.archive.ubuntu.com/ubuntu xenial-updates/main amd64 libgd3 amd64 2.1.1-4ubuntu0.16.04.6 [126 kB]
Get:11 http://ap-south-1.ec2.archive.ubuntu.com/ubuntu xenial/main amd64 libxslt1.1 amd64 1.1.28-2.1 [145 kB]
Get:12 http://ap-south-1.ec2.archive.ubuntu.com/ubuntu xenial-updates/main amd64 nginx-common all 1.10.0-0ubuntu0.16.04.4 [26.6 kB]
Get:13 http://ap-south-1.ec2.archive.ubuntu.com/ubuntu xenial-updates/main amd64 nginx-core amd64 1.10.0-0ubuntu0.16.04.4 [428 kB]
Get:14 http://ap-south-1.ec2.archive.ubuntu.com/ubuntu xenial-updates/main amd64 nginx all 1.10.0-0ubuntu0.16.04.4 [3,498 B]
Fetched 2,999 kB in 2s (1,135 kB/s)
Preconfiguring packages ...
Selecting previously unselected package libjpeg-turbo8:amd64.
(Reading database ... 138589 files and directories currently installed.)
Preparing to unpack .../libjpeg-turbo8_1.4.2-0ubuntu3_amd64.deb ...
Unpacking libjpeg-turbo8:amd64 (1.4.2-0ubuntu3) ...
Selecting previously unselected package libjbig0:amd64.
Preparing to unpack .../libjbig0_2.1-3.1_amd64.deb ...
Unpacking libjbig0:amd64 (2.1-3.1) ...
Selecting previously unselected package fonts-dejavu-core.
Preparing to unpack .../fonts-dejavu-core_2.35-1_all.deb ...
Unpacking fonts-dejavu-core (2.35-1) ...
Selecting previously unselected package fontconfig-config.
Preparing to unpack .../fontconfig-config_2.11.94-0ubuntu1.1_all.deb ...
Unpacking fontconfig-config (2.11.94-0ubuntu1.1) ...
Selecting previously unselected package libfontconfig1:amd64.
Preparing to unpack .../libfontconfig1_2.11.94-0ubuntu1.1_amd64.deb ...
Unpacking libfontconfig1:amd64 (2.11.94-0ubuntu1.1) ...
Selecting previously unselected package libjpeg8:amd64.
Preparing to unpack .../libjpeg8_8c-2ubuntu8_amd64.deb ...
Unpacking libjpeg8:amd64 (8c-2ubuntu8) ...
Selecting previously unselected package libtiff5:amd64.
Preparing to unpack .../libtiff5_4.0.6-1ubuntu0.1_amd64.deb ...
Unpacking libtiff5:amd64 (4.0.6-1ubuntu0.1) ...
Selecting previously unselected package libvpx3:amd64.
Preparing to unpack .../libvpx3_1.5.0-2ubuntu1_amd64.deb ...
Unpacking libvpx3:amd64 (1.5.0-2ubuntu1) ...
Selecting previously unselected package libxpm4:amd64.
Preparing to unpack .../libxpm4_1%3a3.5.11-1ubuntu0.16.04.1_amd64.deb ...
Unpacking libxpm4:amd64 (1:3.5.11-1ubuntu0.16.04.1) ...
Selecting previously unselected package libgd3:amd64.
Preparing to unpack .../libgd3_2.1.1-4ubuntu0.16.04.6_amd64.deb ...
Unpacking libgd3:amd64 (2.1.1-4ubuntu0.16.04.6) ...
Selecting previously unselected package libxslt1.1:amd64.
Preparing to unpack .../libxslt1.1_1.1.28-2.1_amd64.deb ...
Unpacking libxslt1.1:amd64 (1.1.28-2.1) ...
Selecting previously unselected package nginx-common.
Preparing to unpack .../nginx-common_1.10.0-0ubuntu0.16.04.4_all.deb ...
Unpacking nginx-common (1.10.0-0ubuntu0.16.04.4) ...
Selecting previously unselected package nginx-core.
Preparing to unpack .../nginx-core_1.10.0-0ubuntu0.16.04.4_amd64.deb ...
Unpacking nginx-core (1.10.0-0ubuntu0.16.04.4) ...
Selecting previously unselected package nginx.
Preparing to unpack .../nginx_1.10.0-0ubuntu0.16.04.4_all.deb ...
Unpacking nginx (1.10.0-0ubuntu0.16.04.4) ...
Processing triggers for libc-bin (2.23-0ubuntu7) ...
Processing triggers for man-db (2.7.5-1) ...
Processing triggers for ufw (0.35-0ubuntu2) ...
Processing triggers for ureadahead (0.100.0-19) ...
Processing triggers for systemd (229-4ubuntu13) ...
Setting up libjpeg-turbo8:amd64 (1.4.2-0ubuntu3) ...
Setting up libjbig0:amd64 (2.1-3.1) ...
Setting up fonts-dejavu-core (2.35-1) ...
Setting up fontconfig-config (2.11.94-0ubuntu1.1) ...
Setting up libfontconfig1:amd64 (2.11.94-0ubuntu1.1) ...
Setting up libjpeg8:amd64 (8c-2ubuntu8) ...
Setting up libtiff5:amd64 (4.0.6-1ubuntu0.1) ...
Setting up libvpx3:amd64 (1.5.0-2ubuntu1) ...
Setting up libxpm4:amd64 (1:3.5.11-1ubuntu0.16.04.1) ...
Setting up libgd3:amd64 (2.1.1-4ubuntu0.16.04.6) ...
Setting up libxslt1.1:amd64 (1.1.28-2.1) ...
Setting up nginx-common (1.10.0-0ubuntu0.16.04.4) ...
Setting up nginx-core (1.10.0-0ubuntu0.16.04.4) ...
Setting up nginx (1.10.0-0ubuntu0.16.04.4) ...
Processing triggers for libc-bin (2.23-0ubuntu7) ...
Processing triggers for systemd (229-4ubuntu13) ...
Processing triggers for ureadahead (0.100.0-19) ...
Processing triggers for ufw (0.35-0ubuntu2) ...

After successful installation, start nginx service.

# service nginx start (Redhat systems)
Starting nginx:                                            [  OK  ]
OR
# systemctl start nginx (RHEL7 & debian)
Starting nginx:                                            [  OK  ]

Verify service is running.

# service nginx status
nginx (pid  1689) is running...

OR

# systemctl status nginx
● nginx.service - A high performance web server and a reverse proxy server
   Loaded: loaded (/lib/systemd/system/nginx.service; enabled; vendor preset: enabled)
   Active: active (running) since Tue 2017-04-04 10:24:19 UTC; 2min 15s ago
 Main PID: 6734 (nginx)
   CGroup: /system.slice/nginx.service
           ├─6734 nginx: master process /usr/sbin/nginx -g daemon on; master_process on
           └─6735 nginx: worker process

That’s it. Your installation is complete and your webserver is up and running.

Nginx server test

Now you can enter your server IP in the browser (http://x.x.x.x/) to check if your Nginx webserver is serving page or not. If you are getting a connection timed out, you may want to check firewall settings on your server to allow port 80.

You will be served with test page like below :

nginx test page on YUM based systems like Red Hat

nginx test page on APT based systems like Ubuntu

This confirms that your Nginx web server installation is successful and it’s ready for customization.

nginx configurations

The default server root directory is /usr/share/nginx/html. Files that are placed in there will be served on your web server. You can place your HTML files here to serve a static website! The test page you seen above is file index.html under /usr/share/nginx/html. This default directory can be changed under Nginx configuration file /etc/nginx/conf.d/default.conf.

nginx global configuration file is /etc/nginx/nginx.conf. In this conf file, you can set the user to run Nginx, its number of processes to fork, etc.

Default log files error.log (for errors) and access.log (logging accesses) are located under /var/log/nginx

Directory listing in nginx

If you place a few files or directories in root directory then you will not see a listing of them in your browser as we saw in Apache configuration. To enable this you need to add autoindex on; in config file after root directive. Look at my config below :

# cat /etc/nginx/conf.d/default.conf
server {
    listen       80 default_server;
    listen       [::]:80 default_server;
    server_name  _;
    root         /tmp;
    autoindex on;

----- output clipped ----

In the above config, I defined /tmp as root and turned on autoindex (highlighted lines). Restart Nginx services after saving the above changes. Now if I check my webpage (http://x.x.x.x/) it will list all files/directories under /tmp

You can see in above screenshot, /tmp directory listing is presented by Nginx. If you don’t put autoindex on then it will serve you 404 forbidden error!

How to install Apache webserver in Linux

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Step by step procedure to install and configure Apache webserver in Linux. It also includes troubleshooting steps for errors during install.

In this tutorial, we are going to see how to install and configure Apache webserver in Linux. Apache is the most widely used web server that is developed and maintained by Apache Software Foundation. Its an open-source software and available for free to download and use.

What is webserver

The webserver is aimed to serve web pages to its clients. In our daily life websites, we visit from browsers that are hosted on webservers! Webserver commonly runs on port 80 (HTTP protocol) and 443 (https protocol, more secured). Communication between the web server and its client over https protocol is encrypted and hence secured.

Apache webserver

Apache webserver is an open-source web server developed by Apache Software Foundation. It is named as Apache HTTP Server Project and details can be viewed here. Apache webserver is also a part of the LAMP stack. Read more about LAMP here. Let’s see how to set up the Apache web server on the Linux box.

Apache installation

If you have configured YUM repositories then you can install ‘httpd’ package. If you don’t have YUM or apt-get repositories configured you can download the latest Apache source, compile and then install it.

Number of errors and their solutions :

Error: configure: error: APR not found.
Solution: Install apr and apr-utils packages (download here if you don’t have yum)

Error: configure: error: no acceptable C compiler found in $PATH
Solution: Install GCC package

Error: configure: error: pcre-config for libpcre not found.
Solution: Install pcre package (download here, unzip, /configure --prefix=/usr/local/pcre, make, make install)

Finally, you should be able to install it using : ./configure --prefix=/apache, make, make install (you can change /apache directory to diff where it will be installed)

Apache configuration

Post-installation you will have /var/www/html/ directory in which you should place your HTML pages which can be fetched from browser. httpd service will come to existence.

If you keep files and directories in /var/www/html/ then its listing will be shown in a browser like this example we saw in another post. We will put below HTML file in /var/www/html/ for test :

# cat test.html
<html>
<body>
<h4>This webserver is installed by kerneltalks.com</h4>
</body>
</html>

Now once you make changes in the directory structure, restart httpd service. Verify httpd service is running and port 80 is listening.

# service httpd status
httpd (pid  27920) is running...

Now, try to fetch that page from browser. Use your server IP as website address i.e. http://IP/test.html

You will be greeted with such a page! Your webserver is up and running. Accepting and serving requests from browsers.

Apache config files

Apache configuration file located at /etc/httpd/conf/httpd.conf In this configuration file you can set your error file path, SSL certificate path, SSL cert key file path, port, IP (virtual hosts), access log path, etc. There is a lot more customization that can be done using this file but I stated only general tweaking parameters.

Apache log files can be found at :

/etc/httpd/logs/access_log: all access logs logged here.
/etc/httpd/logs/error_log: All errors logged here. They also include start-stop service messages.

How to start / stop Apache webserver

To start Apache webserver

# service httpd start
# service apache2 start   #If you are running Apache2

To stop Apache webserver

# service httpd stop
# service apache2 stop   #If you are running Apache2

How to load Apache2 modules

One of the common issues found is when the PHP module is not loaded into Apache webserver, .php links on webserver will download files in the browser instead of displaying them. To correct this you need to load the PHP module in Apache.

To load PHP or any other module in Apache, you need to add it in file /etc/sysconfig/apache2 in below line :

APACHE_MODULES="actions alias auth_basic authn_file authz_host authz_groupfile authz_core authz_user autoindex cgi dir env expires include log_config mime negotiation setenvif ssl socache_shmcb userdir reqtimeout authn_core php5"

Here you can see we are loading the php5 module in our Apache2 webserver. Then you need to restart Apache2 webserver. Once done, check if the PHP module is loaded or not. Use command apache2ctl -M to check loaded modules in Apache.

How to list Apache modules in Linux

 # apache2ctl -M
Loaded Modules:
 core_module (static)
 so_module (static)
 http_module (static)
 mpm_prefork_module (static)
 unixd_module (static)
 systemd_module (static)
 actions_module (shared)
 alias_module (shared)
 auth_basic_module (shared)
 authn_file_module (shared)
 authz_host_module (shared)
 authz_groupfile_module (shared)
 authz_core_module (shared)
 authz_user_module (shared)
 autoindex_module (shared)
 cgi_module (shared)
 dir_module (shared)
 env_module (shared)
 expires_module (shared)
 include_module (shared)
 log_config_module (shared)
 mime_module (shared)
 negotiation_module (shared)
 setenvif_module (shared)
 ssl_module (shared)
 socache_shmcb_module (shared)
 userdir_module (shared)
 reqtimeout_module (shared)
 authn_core_module (shared)
 php5_module (shared)

You can see our php5 module is loaded in Apache.

What is difference between Server Root and Document Root in Apache ?

Server root is where Apache executable binaries reside rather its an installation path for Apache. Whereas document root is where website pages reside i.e. from where webserver loads web pages. So, you can change Document Root if you don’t want to use default /srv/www/htdocs directory. You can change it to any directory where you keep your website pages.

How to check if the package is installed on Linux

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Learn to check if the package is installed on the Linux server or not. Verify if the package available on the server along with its installed date.

Package installation on Linux sometimes fails with error package is already installed; nothing to do. To avoid this you need to first check if the package is installed on system or not and then attempt its installation. In this article, we will be seeing different ways we can check if the package is installed on the server and also check its installation date.

Package management related reads :

Different ways to check if package is installed or not :

On RPM based system

RPM-based systems like Red Hat, CentOS, etc, we can use rpm query command like below :

# rpm -qa |grep telnet
telnet-0.17-60.el7.x86_64
OR
# rpm -q telnet
telnet-0.17-60.el7.x86_64

We are using -qa i.e. query all options which will list all installed packages on the system. We are grepping out our desired (telnet in this example) package name. If the output is blank then the package is not installed. If it’s installed then the respective name will be shown (like above). To understand what these numbers in package name mean read package naming conventions.

Or even directly querying the package name will yield you the same result as the second example above.

If the system is configured with YUM then it can list all installed packages for you and you can grep out your desired package from it.

# yum list installed telnet
Loaded plugins: amazon-id, rhui-lb, search-disabled-repos
Installed Packages
telnet.x86_64                                                            1:0.17-60.el7                                                            @rhui-REGION-rhel-server-releases
OR
# yum list installed |grep telnet                                                                                                                        
telnet.x86_64                    1:0.17-60.el7              @rhui-REGION-rhel-server-releases

On APT based systems

APT based systems like Debian, Ubuntu, etc, dpkg command can be used to verify if the package is installed –

# dpkg -l |grep telnet
ii  telnet                           0.17-40                            amd64        basic telnet client

Column wise fields in output are Name, Version, Architecture, Description.

If you have an apt repository configured then you can try to install emulation of the desired package. If it’s installed then the respective message will be shown in output (highlighted line below). If it’s not installed then output just emulates installation process and exits without actually installing. –

# apt-get install -s telnet
Reading package lists... Done
Building dependency tree
Reading state information... Done
telnet is already the newest version (0.17-40).
0 upgraded, 0 newly installed, 0 to remove and 0 not upgraded.

Package installation date

One of the Linux interview questions is how to find the package installation date? or how to check when the package was installed in Linux? Answer is –

On YUM based systems

rpm command has a direct option of sorting packages with their installed date --last. Grep your desired package and you will get its installed date.

# rpm -qa --last |grep telnet
telnet-0.17-60.el7.x86_64                     Fri 10 Mar 2017 01:58:17 PM EST

On APT based systems

Here there is no direct command which shows installation date. You have to grep ‘install’ word through installer log files /var/log/dpkg.log to get the installation date. If logrotate is configured on the system then use wild card * to search through all rotated and current log files.

If you observe this file does not exist on your server then install operation wasn’t performed on that system after its setup. On the very first install operation (using apt-get or dpkg) this file will get created and start logging installation details.

# grep install /var/log/dpkg.log* |grep telnet
2017-03-10 19:26:30 status installed telnet:amd64 0.17-40
2017-03-10 19:26:30 status half-installed telnet:amd64 0.17-40
2017-03-10 19:26:40 install telnet:amd64 0.17-40 0.17-40
2017-03-10 19:26:40 status half-installed telnet:amd64 0.17-40
2017-03-10 19:26:40 status installed telnet:amd64 0.17-40

Understanding package naming convention (rpm & deb)

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This article will help you understand the package naming convention followed while naming RPM or DEB packages. It helps while you work on package management.

Linux world is moved by packages since you need a flavor punch on plain vanilla OS! Although there are quite a few package managers available in the market largely two package managers are popular: RPM (Red Hat package manager) & DEB (Debian package manager).

Red Hat package managers release their packages with extension .rpm while Debian package managers have .deb extension. The extension really doesn’t matter in Linux world but still, it’s there for identification purposes for humans!

Recommended read:

Apart from extensions they also have a package naming convention which makes it easy to identify package name, version, release & what architecture it supports. Lets quickly walk through these conventions.

Red Hat package naming convention

Red Hat package name follows below format –

packagename-version-release.architecture.rpm

Field involved here are

It starts with the package name
Then its version (separated by hyphen – from the last field)
Then its release (separated by hyphen – from the last field)
Sometimes OS details are padded here (separated by a dot . from the last field)
Then architecture for which package built (separated by a dot . from the last field)
Ends with rpm extension (separated by a dot . from the last field)

For example, look at this telnet package file name “telnet-0.17-60.el7.x86_64.rpm“

Here,

telnet is a package name
0.17 is version
60 is release
el7 is enterprise Linux 7 (package built for rhel7)
x86_64 is architecture

Extra OS details mentioned in names can be :

elX or rhlX – RHEL X
suseXXY – Suse Linux XX.Y
fcX – Fedora Core X
mdv or mdk – Mandriva Linux

Debian package naming convention

Debian package name follows below format –

packagename_version-release_architecture.deb

Field involved here are

It starts with the package name
Then its version (separated by underscore – from the last field)
Then its release (separated by a hyphen – from the last field)
Sometimes Debian codename details are padded here (separated by hyphen – from the last field)
Then architecture for which package built (separated by a dot . from the last field)
Ends with deb extension (separated by a dot . from the last field)

Debian codename can be squeeze or wheezy.

For example look at this telnet package file name “telnet_0.17-40_amd64.deb“

Here,

telnet is a package name
0.17 is version
40 is release
amd64 is architecture

Different types of architectures which can be seen in names are :

x86_64 or amd64 – 64 bit on x86 microprocessor
i386 – The Intel x86 family of microprocessors, starting with the 80386.
ppc – The Power PC microprocessor family.
alpha – The Digital Alpha microprocessor family.
sparc – Sun Microsystem SPARC processor family.
noarch – No particular architecture. The package may work on all types of architecture.

Package removal in Linux (YUM & APT)

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Different types of package removal in Linux explained with examples. Learn package removal or uninstall on a yum or apt-based system.

This article is part of the YUM series. Other articles in this series can be found at below links :

We will be seeing how to uninstall packages from YUM and APT based Linux systems. Package removal also knows as an erasing package from the system.

Package removal on YUM based system

Removing package using yum

On YUM based system like Red Hat or CentOS, the package can be removed by supplying erase or remove argument to yum command along with package name. For example to remove telnet, we will use yum remove telnet

# yum remove telnet
Loaded plugins: amazon-id, rhui-lb, search-disabled-repos
Resolving Dependencies
--> Running transaction check
---> Package telnet.x86_64 1:0.17-60.el7 will be erased
--> Finished Dependency Resolution

Dependencies Resolved

=============================================================================================================================================================
 Package                      Arch                         Version                             Repository                                               Size
=============================================================================================================================================================
Removing:
 telnet                       x86_64                       1:0.17-60.el7                       @rhui-REGION-rhel-server-releases                       113 k

Transaction Summary
=============================================================================================================================================================
Remove  1 Package

Installed size: 113 k
Is this ok [y/N]: y
Downloading packages:
Running transaction check
Running transaction test
Transaction test succeeded
Running transaction
  Erasing    : 1:telnet-0.17-60.el7.x86_64                                                                                                               1/1
  Verifying  : 1:telnet-0.17-60.el7.x86_64                                                                                                               1/1

Removed:
  telnet.x86_64 1:0.17-60.el7

Complete!

The above output will be the same even if you use yum erase telnet command. Before removing it will print package details to be removed on screen and ask for confirmation to avoid unwanted removals.

Removing package using rpm command

Same task can be achieved by using rpm command with erase -e option.

# rpm -evh telnet
Preparing...                          ################################# [100%]
Cleaning up / removing...
   1:telnet-1:0.17-60.el7             ################################# [100%]

In above example we used -e (erase), -v (verbose) and -h (print hash marks) along with name of package.

Package removal on APT based system

Removing package using apt-get

On APT based systems like Ubuntu or Debian, the package can be removed with apt-get remove <package_name> command. Note that like YUM this command doesn’t support erase option.

# apt-get remove telnet                                                                                                                                      
Reading package lists... Done
Building dependency tree       
Reading state information... Done
The following packages will be REMOVED:
  telnet
0 upgraded, 0 newly installed, 1 to remove and 60 not upgraded.
After this operation, 182 kB disk space will be freed.
Do you want to continue? [Y/n] y
(Reading database ... 81678 files and directories currently installed.)
Removing telnet (0.17-40) ...
Processing triggers for man-db (2.7.5-1) ...

apt-get to asks for confirmation before removing package from system.

Removing package using dpkg

With Debian package manager command i.e. dpkg, this can be done using --remove argument.

# dpkg --remove telnet
(Reading database ... 81678 files and directories currently installed.)
Removing telnet (0.17-40) ...
Processing triggers for man-db (2.7.5-1) ...

See above output as it removes telnet.

Observe that dpkg or rpm commands don’t ask for user confirmation before removing the package.

Package installation in Linux (YUM,APT & zypper)

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Different types of package installations in Linux explained with examples. Learn package installation on a yum or apt-based system.

One of the sysadmin tasks in Linux administration is package management. Under which he needs to install, remove, upgrade packages on the system. In another post, we already saw package/patch installation in HPUX (Unix based system), in this article we will be studying package installation in Linux.

There are many distributions in the market and they support different ways to manage packages on the system. Distros like Red Hat, Cent OS supports YUM (Yellow dog Updater Modified) whereas distros like Debian or Ubuntu support APT (Advanced Packaging Tool).

YUM based system uses packages with .rpm extension (RedHat package manager) whereas APT based systems use packages with .deb extension (Debian distribution)

Package installation on YUM based system

YUM needs to be configured properly to receive package inventory from source server over HTTP/FTP etc. If not then you should have a package file (.rpm) with you.

Installing package from list using yum in RHEL / CentOS

YUM is smart enough to locate packages for you. For instance, if you want to install a telnet package, you are not supposed to supply a complete telnet package name which includes version, architecture, etc details in the name. Typing yum install telnet is enough. YUM will search the package with the name telnet and confirm with you before installation.

root@kerneltalks # yum install telnet
Loaded plugins: amazon-id, rhui-lb, search-disabled-repos
Resolving Dependencies
--> Running transaction check
---> Package telnet.x86_64 1:0.17-60.el7 will be installed
--> Finished Dependency Resolution

Dependencies Resolved

=============================================================================================================================================================
 Package                      Arch                         Version                              Repository                                              Size
=============================================================================================================================================================
Installing:
 telnet                       x86_64                       1:0.17-60.el7                        rhui-REGION-rhel-server-releases                        63 k

Transaction Summary
=============================================================================================================================================================
Install  1 Package

Total download size: 63 k
Installed size: 113 k
Is this ok [y/d/N]: y
Downloading packages:
telnet-0.17-60.el7.x86_64.rpm                                                                                                         |  63 kB  00:00:00
Running transaction check
Running transaction test
Transaction test succeeded
Running transaction
  Installing : 1:telnet-0.17-60.el7.x86_64                                                                                                               1/1
  Verifying  : 1:telnet-0.17-60.el7.x86_64                                                                                                               1/1

Installed:
  telnet.x86_64 1:0.17-60.el7

Complete!

In the above output, you can see the install process goes through stages checks, resolving dependencies, printing details, confirmation from the user, downloading, installing, verifying. You can even download the only package using this command.

Recommended read : How to upgrade package using YUM

Installing a standalone package using rpm in RHEL / CentOS

If you don’t have yum repositories setup and have standalone package file (.rpm) then you can install it using rpm -i command.

root@kerneltalks # rpm -ivh telnet-0.17-60.el7.x86_64.rpm
Preparing...                          ################################# [100%]
Updating / installing...
   1:telnet-1:0.17-60.el7             ################################# [100%]

In the above command, we used -v verbose mode and -h to print progress hash marks!

Package installation on APT based system

APT configuration needs to be in place to fetch packages from the source server. If not then at least you should have a package file .deb with you for installation.

Installing package from list using apt-get on Ubuntu / Debian

apt-get command used for package management. For installing new package use apt-get install <package-name>. See below example for installing telnet package :

root@kerneltalks # apt-get install telnet                                                                                                                                      
Reading package lists... Done
Building dependency tree       
Reading state information... Done
The following NEW packages will be installed:
  telnet
0 upgraded, 1 newly installed, 0 to remove and 0 not upgraded.
Need to get 0 B/63.5 kB of archives.
After this operation, 182 kB of additional disk space will be used.
Selecting previously unselected package telnet.
(Reading database ... 53784 files and directories currently installed.)
Preparing to unpack .../telnet_0.17-40_amd64.deb ...
Unpacking telnet (0.17-40) ...
Processing triggers for man-db (2.7.5-1) ...
Setting up telnet (0.17-40) ...
update-alternatives: using /usr/bin/telnet.netkit to provide /usr/bin/telnet (telnet) in auto mode

You can see in the above output, it first checks the availability of the stated package in the package list. Then it prints install-info along with size details. Then it downloads a package, unpacks it, installs it, and completes configurations.

While installing a new package, default dependencies will be checked and resolved. There are a few options which you can use with install operation :

-d: download only package in the current directory
-q: quiet operation
-v: verbose mode
-s: simulate/dry run. Don’t actually install.

Installing standalone package using dpkg on Debian / Ubuntu

If you have a package file (.deb) with you on the server and you want to install it then you can use dpkg command. Supply package file path along with -i option.

root@kerneltalks # dpkg -i telnet_0.17-40_amd64.deb                                                                                                                       
Selecting previously unselected package telnet.
(Reading database ... 53784 files and directories currently installed.)
Preparing to unpack telnet_0.17-40_amd64.deb ...
Unpacking telnet (0.17-40) ...
Setting up telnet (0.17-40) ...
update-alternatives: using /usr/bin/telnet.netkit to provide /usr/bin/telnet (telnet) in auto mode
Processing triggers for man-db (2.7.5-1) ...

The command will set up the package for you with an almost the same sequence as apt-get only looking for a package in the list and downloading stuff omitted.

Installing package using zypper in Suse Linux

In Suse Linux, zypper is mainly used for package management. You can use install or in switch followed by package name to install package using zypper.

root@kerneltalks # zypper install telnet
Refreshing service 'SMT-http_smt-ec2_susecloud_net'.
Refreshing service 'cloud_update'.
Loading repository data...
Reading installed packages...
Resolving package dependencies...

The following NEW package is going to be installed:
  telnet

1 new package to install.
Overall download size: 51.8 KiB. Already cached: 0 B. After the operation, additional 113.3 KiB will be used.
Continue? [y/n/...? shows all options] (y): y
Retrieving package telnet-1.2-165.63.x86_64                                                                                        (1/1),  51.8 KiB (113.3 KiB unpacked)
Retrieving: telnet-1.2-165.63.x86_64.rpm .........................................................................................................................[done]
Checking for file conflicts: .....................................................................................................................................[done]
(1/1) Installing: telnet-1.2-165.63.x86_64 .......................................................................................................................[done]

zypper also auto-resolve dependencies and install them along with your required package.

What is the difference between su and sudo?

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Learn the difference between su and sudo. By learning difference you will be able to judge which one is best suited for your requirement of access management.

Granting access to someone’s account to someone is a security threat and should be handled cautiously. Its a part of access management and one should which is the best fit tool for his requirement.

The first question will be why to give someone else’s access to another account?

There are situations like when a normal user needs a superuser privilege to run a few commands only maybe during installation or configuration of his application. Sometimes a normal user needs to execute some database-related tasks which will need access to DB privileged account. So, there are situations that arise in which one user needs access to some other user’s privilege (normally superuser access).

What are available ways to share account access?

Very obvious way and too risky is to share the password of another account which generally not at all suggested and implemented in production environments.
Use sudo to define access to specific commands as a different user
Use su to switch to another account

Difference between su and sudo :

sudo aims at allowing only a few commands (specified in configuration) to run as a different user with their level of access whereas su directly takes you to a different user account so that you have complete access which is owned by that account.

sudo executes commands while the environment of current user loaded. With su you can load the complete environment of the destination account.

So su opens up Pandora box to you! Once you are into different user’s account, you can do whatever you want using that account with its level of access. Imagine if it’s a superuser account, you have full access to the system. This is dangerous! Since the system administrator has no control which command you execute as a different user.

On another hand, sudo allows only specific commands to be executed as a different user with its level of access. This limits your use as a different account and system administrator has complete control over tasks you perform using other account’s level of access.

In a sentence, we can say that sudo awards superuser ability to the normal user without logging into superuser account while su is logging into superuser accounts to get that level of access.

Hence, its always advisable to use sudo for access management than su. SU will be best fitted only in case you trust user getting access won’t misuse it & that user also well aware that what he is doing on the system.

The complete guide: logrotate utility on Linux

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Learn everything about logrotate utility in Linux. This post explains what is it, why to use it, and its configuration steps.

What is logrotate?

First of all, but an obvious introduction to logrotate tool. It is a utility which rotates, compress, purge, email logs once they match specified criteria like size, an age defined in the configuration. In short, its an automated log management tool.

It offers service (log specific) policies that can be set and it will handle logs accordingly. Conditions to trigger logrotate can be set on a size basis or time basis like daily, weekly, or monthly.

Why to rotate logs ?

Another obvious question is why to rotate logs? Logs are files that grow over time. Since they keep on filling over time. If you don’t maintain them they will end up filling your mount point which you never want to see in production!

Means, to save your disk space logs should be rotated. Logs are always useful for troubleshooting but yes you don’t need pretty old logs keeping your disk space on toss! Logs can be purged, compressed, or moved manually. But to save your time from manual tasks you can automate log management using this tool.

Logrotate Installation:

Let’s walk through logrotate configuration. How to install it, how to configure it as per your requirement etc.

First of all, you need to install logrotate utility on your machine like below (Red Hat, CentOS, Fedora):

For Debian, ubuntu use : apt-get install logrotate

# yum install logrotate
Loaded plugins: amazon-id, rhui-lb, security
Setting up Install Process
Resolving Dependencies
--> Running transaction check
---> Package logrotate.x86_64 0:3.7.8-26.el6_7 will be installed
--> Finished Dependency Resolution

Dependencies Resolved

=============================================================================================================================================================
 Package                        Arch                        Version                              Repository                                             Size
=============================================================================================================================================================
Installing:
 logrotate                      x86_64                      3.7.8-26.el6_7                       rhui-REGION-rhel-server-releases                       58 k

Transaction Summary
=============================================================================================================================================================
Install       1 Package(s)

Total download size: 58 k
Installed size: 87 k
Is this ok [y/N]: y
Downloading Packages:
logrotate-3.7.8-26.el6_7.x86_64.rpm                                                                                                   |  58 kB     00:00
Running rpm_check_debug
Running Transaction Test
Transaction Test Succeeded
Running Transaction
  Installing : logrotate-3.7.8-26.el6_7.x86_64                                                                                                           1/1
  Verifying  : logrotate-3.7.8-26.el6_7.x86_64                                                                                                           1/1

Installed:
  logrotate.x86_64 0:3.7.8-26.el6_7

Complete!

Confirm if its installed

# rpm -q logrotate
logrotate-3.7.8-26.el6_7.x86_64

Once logrotate is confirmed installed move on to configurations.

Logrotate configuration :

/etc/logrotate.conf is the main configuration file. Individual service-specific configuration files can be kept under directory /etc/logrotate.d

To use these service-specific individual config files you must include below the line in /etc/logrotate.conf

include /etc/logrotate.d

Let’s configure logrotate to manage /var/log/messages (Syslog in Linux). To keep things clean, its recommended to create individual configs under /etc/logrotate.d. We will create rotate_syslog.conf file under this directory and add the below code.

/var/log/messages {
daily
rotate 3
size 10M
compress
delaycompress
}

Now understand each filed specified in conf file –

daily: Rotate logs on daily basis
rotate 3: Means keep last 3 rotated logs. Older copies to be purged.
size 10M: Min size for rotation is 10MB i.e. logs won’t be rotated unless they grow more than 10MB
compress: Compress rotated logs
delaycompress: Do not compress current log and last rotated log.

Above all options in config file tells logrotate to rotate /var/log/messages logs when they grow over 10MB. After rotation keeps any extra logs than the last 3 one. Also, compress logs except current and last rotated one. Check for size daily and if found >10MB then rotate.

logroate testing :

We will dry run the above config file to check how it will work in the actual run. -d option dry runs utility but doesn’t rotate logs in actual. We have 21MB /var/log/messages file on the machine.

# logrotate -d /etc/logrotate.d/rotate_syslog.conf
reading config file /etc/logrotate.d/rotate_syslog.conf
reading config info for /var/log/messages

Handling 1 logs

rotating pattern: /var/log/messages  10485760 bytes (3 rotations)
empty log files are rotated, old logs are removed
considering log /var/log/messages
  log needs rotating
rotating log /var/log/messages, log->rotateCount is 3
dateext suffix '-20170224'
glob pattern '-[0-9][0-9][0-9][0-9][0-9][0-9][0-9][0-9]'
previous log /var/log/messages.1 does not exist
renaming /var/log/messages.3.gz to /var/log/messages.4.gz (rotatecount 3, logstart 1, i 3),
renaming /var/log/messages.2.gz to /var/log/messages.3.gz (rotatecount 3, logstart 1, i 2),
renaming /var/log/messages.1.gz to /var/log/messages.2.gz (rotatecount 3, logstart 1, i 1),
renaming /var/log/messages.0.gz to /var/log/messages.1.gz (rotatecount 3, logstart 1, i 0),
renaming /var/log/messages to /var/log/messages.1
removing old log /var/log/messages.4.gz
error: error opening /var/log/messages.4.gz: No such file or directory

In above output you can see, it rotate logs, compress them (gz extensions), renames them to maintain iterations, try to purge older than 3 logs

When I dry run on file with 9MB size, it gave me below output :

# logrotate -d /etc/logrotate.d/rotate_syslog.conf
reading config file /etc/logrotate.d/rotate_syslog.conf
reading config info for /var/log/messages

Handling 1 logs

rotating pattern: /var/log/messages  10485760 bytes (3 rotations)
empty log files are rotated, old logs are removed
considering log /var/log/messages
  log does not need rotating

Since we specified 10MB size to rotate log and our file is less than 10MB, logrotate reported no need to rotate logs!

You can observe logrotate entry being added to /etc/cron.daily directory too.

# cd /etc/cron.daily
# ll
total 32
-rwx------. 1 root root  118 Jun 10  2015 cups
-rwx------. 1 root root  180 Jul  9  2015 logrotate
-rwxr-xr-x. 1 root root  905 Nov 16  2012 makewhatis.cron
-rwx------. 1 root root  189 Jan 26  2015 mlocate.cron
-rwxr-xr-x. 1 root root 2126 Jul 19  2013 prelink
-rwxr-xr-x. 1 root root  563 Oct 21  2013 readahead.cron
-rwx------. 1 root root  256 Jun  9  2015 rhsmd
-rwxr-xr-x. 1 root root  416 Oct 14  2015 tmpwatch

logroatete available options :

Below is a list of logrotate options that can be used in configuration files along with their meaning.

daily,monthly, weekly: when to rotate logs (if conditions meet)
rotate N: Purge all older logs keeping the last N rotated logs on the server
size X: Rotate logs when they grow more than X size
compress: Compress rotated logs using gzip (there are more options to choose compression commands, extensions, etc if you want)
delaycompress: Don’t compress current and last rotated log file
copy: Make a copy of the current log file
create mode user group: After rotation create an empty log file with permission (mode), user and group specified
dateext: Append the date to rotated file names
mail: Mail rotated logs to email before deletion (more options available with this)
ifempty: Rotate log even if it’s empty
maxage N: Rotate logs older than N days
maxsize N: Rotate when they have grown beyond N size even before run-time daily, weekly or monthly.

There are many other options available that can be used. I have listed here only frequently used ones. A detailed list can be obtained on the man page of logrotate.

All the above outputs are from the RHEL6 box. Let me know if you have any queries in the comments or if you are looking for specific options to rotate logs with your requirement.