# make
gcc -DHAVE_CONFIG_H -I. -I. -I. -g -O2 -Wall -Wno-comment -c cmatrix.c
cmatrix.c:37:20: fatal error: curses.h: No such file or directory
#include <curses.h>
^
compilation terminated.
make: *** [cmatrix.o] Error 1
After troubleshooting I came up with a solution and able to pass through make stage. I am sharing it here which might be useful for you.
curses.h header file belongs to ncurses module! You need to install packagesncurses-devel,ncurses (YUM) or libncurses5-dev (APT) and you will be through this error.
Use yum install ncurses-devel ncurses for YUM based systems (like Red Hat, CentOS, etc.) or apt-get install libncurses5-dev for APT based systems (like Debian, Ubuntu, etc.) Verify once that package is installed and proceed with your next course of action.
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.
Check if package in installed on Linux
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.
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 –
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
Article explaining service management in Linux. Learn how to restart service in Linux distro like Red Hat, Debian, Ubuntu, CentOS, etc.
Service management in Linux
Managing services in Linux is one of the frequent task sysadmins need to take care of. In this post, we will be discussing several operations like –
How to stop service in Linux
How to start service in Linux
How to restart service in Linux
How to check the status of service in Linux
Different distributions have different ways of service management. Even within the same distro, different versions may have different service management aspects. Like RHEL 6 and RHEL7 has different commands to manage services.
Let’s see service related tasks in various flavors of Linux –
How to stop service in Linux
Service can be stopped with below commands (respective distro specified)
here <name> is service name like telnet, NTP, NFS, etc. Note that upstart is pre-installed with Ubuntu 6.10 later, if not you can install using the APT package.
Newer versions are implementing systemctl now in place of service command. Even if you use service command in RHEL7 then it will call systemctl in turns.
# service sshd-keygen status
Redirecting to /bin/systemctl status sshd-keygen.service
● sshd-keygen.service - OpenSSH Server Key Generation
Loaded: loaded (/usr/lib/systemd/system/sshd-keygen.service; static; vendor preset: disabled)
Active: inactive (dead)
-----output clipped-----
In the above output, you can see it shows you which systemctl command its executing in place of service command. Also, note that it appends .service to service_name supplied to service command.
Old service commands like RHEL6 & lower, prints status of operation as OK (success) or FAILED (failure) for start, stop, restart operations. systemctl the command doesn’t print any output on the console.
It stops service and then immediately starts it. So basically its a combined command of above two.
Mostly to reload edited new configuration we seek restart of service. But this can be done without restarting it provided service supports reload config. This can be done by using reload option instead of restart.
How to check the status of service in Linux
Checking the status of service makes you aware of if service is currently running or not. Different distros give different details about service in the output of status. Below are a few examples for your reference.
Service status information in Ubuntu :
# service cron status
â cron.service - Regular background program processing daemon
Loaded: loaded (/lib/systemd/system/cron.service; enabled; vendor preset: enabled)
Active: active (running) since Fri 2017-03-10 17:53:23 UTC; 2s ago
Docs: man:cron(8)
Main PID: 3506 (cron)
Tasks: 1
Memory: 280.0K
CPU: 1ms
CGroup: /system.slice/cron.service
ââ3506 /usr/sbin/cron -f
Mar 10 17:53:23 ip-172-31-19-90 systemd[1]: Started Regular background program processing daemon.
Mar 10 17:53:23 ip-172-31-19-90 cron[3506]: (CRON) INFO (pidfile fd = 3)
Mar 10 17:53:23 ip-172-31-19-90 cron[3506]: (CRON) INFO (Skipping @reboot jobs -- not system startup)
It has details about the service state, its man page, PID, CPU & MEM utilization, and recent happenings from the log.
Service status information in RHEL6:
# service crond status
crond (pid 1474) is running...
It only shows you PID and state of service.
Service status information in RHEL7:
# systemctl status crond.service
â crond.service - Command Scheduler
Loaded: loaded (/usr/lib/systemd/system/crond.service; enabled; vendor preset: enabled)
Active: active (running) since Fri 2017-03-10 13:04:58 EST; 1min 2s ago
Main PID: 499 (crond)
CGroup: /system.slice/crond.service
ââ499 /usr/sbin/crond -n
Mar 10 13:04:58 ip-172-31-24-59.ap-south-1.compute.internal systemd[1]: Started Command Scheduler.
Mar 10 13:04:58 ip-172-31-24-59.ap-south-1.compute.internal systemd[1]: Starting Command Scheduler...
Mar 10 13:04:58 ip-172-31-24-59.ap-south-1.compute.internal crond[499]: (CRON) INFO (RANDOM_DELAY will be scaled with factor 85% if used.)
Mar 10 13:04:59 ip-172-31-24-59.ap-south-1.compute.internal crond[499]: (CRON) INFO (running with inotify support)
It prints all details as Ubuntu but doesn’t show CPU and memory utilization, manpage.
List all services on the system
If you want to see all services running on the system and their statuses then you can use below command :
# service --status-all (RHEL6 & lower, Ubuntu, CentOS, Debian, Fedora)
# systemctl list-units --type service --all (RHEL7)
It will present you list of all services and their status with few other details.
Learn how to use two utilities called figlet and toilet to create beautiful ASCII text banners in the Linux terminal. Stylize your terminal!
Beautiful text banners in Linux
Have you seen some stylish ASCII text banners during login on some servers? Or have you seen pages of this blog that have titles written in ASCII? Check out a few styles below too.
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _
/ \ / \ / \ / \ / \ / \ / \ / \ / \ / \ / \ / \ / \ / \ / \
( k | e | r | n | e | l | t | a | l | k | s | . | c | o | m )
\_/ \_/ \_/ \_/ \_/ \_/ \_/ \_/ \_/ \_/ \_/ \_/ \_/ \_/ \_/
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|k|e|r|n|e|l|t|a|l|k|s|.|c|o|m|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| _ ._._ _ |_|_ _.|| _ _ _ ._ _
|<(/_| | |(/_| |_(_|||<_>o(_(_)| | |
Beautiful eh? You can create them too with tools called figlet and toilet!
figlet tool
It’s a command-line text styling utility. You need to install figlet package. Once installed you can supply the text you want to stylize to figlet command and it will print stylish output on your terminal. You can copy it and use it anywhere. All the above texts are printed using the figlet only. By default, it will print in below style –
These text banners are useful to stylize your server’s login screens and print messages to users in a beautiful way!
Below are few examples of figlet in quick run :
figlet utility examples
toilet tool
I know its funny name. Yeah but it’s a tool which do exist in Linux! Check if the toilet package is installed or not and install it if required. Once installed you can submit text to toilet command.
cmatrix: One of the command to have fun in a Linux terminal. It will turn your terminal into the Hollywood movie “MATRIX” like a cool desktop.
Hollywood movie MATRIX falling code in Linux terminal
About cmatrix program:
It’s written by Chris Allegretta. The Cmatrix page can be found here. This program is distributed via the GNU GPL and its Sourceforge page is here. To download the latest release visit Sourceforge page.
Have you seen the Hollywood movie “Matrix”? You must have liked those monitors with falling green code. It looks like a cool hacker/coder desktop! After the movie went to the box office, many matrix screensavers were out for windows. Do you want one for Linux? Like the one below?
Matrix falling code in terminal
Yes, that’s possible. You can have such a matrix-like desktop in Linux terminal too. In very simple two steps.
If you don’t have a YUM repository configured then you can download a standalone file (check Sourceforge page if this link is broken). Then follow below commands to set it up from source code.
Download above mentioned file, un-zip, un-tar it and goto unpacked directory cmatrix-1.2a
Within cmatrix directory execute below commands.
# aclocal
aclocal: warning: autoconf input should be named 'configure.ac', not 'configure.in'
# autoconf
# automake -a
automake: warning: autoconf input should be named 'configure.ac', not 'configure.in'
configure.in:3: warning: AM_INIT_AUTOMAKE: two- and three-arguments forms are deprecated. For more info, see:
configure.in:3: http://www.gnu.org/software/automake/manual/automake.html#Modernize-AM_005fINIT_005fAUTOMAKE-invocation
Makefile.am: installing './depcomp'
automake: warning: autoconf input should be named 'configure.ac', not 'configure.in'
Then configure and make ready to install.
# ./configure
checking for a BSD-compatible install... /bin/install -c
checking whether build environment is sane... yes
/root/cmatrix-1.2a/missing: Unknown `--is-lightweight' option
Try `/root/cmatrix-1.2a/missing --help' for more information
configure: WARNING: 'missing' script is too old or missing
checking for a thread-safe mkdir -p... /bin/mkdir -p
checking for gawk... gawk
checking whether make sets $(MAKE)... yes
checking whether make supports nested variables... yes
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 for style of include used by make... GNU
checking dependency style of gcc... gcc3
checking whether make sets $(MAKE)... (cached) yes
checking for main in -lncurses... yes
checking how to run the C preprocessor... gcc -E
checking for grep that handles long lines and -e... /bin/grep
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 fcntl.h usability... yes
checking fcntl.h presence... yes
checking for fcntl.h... yes
checking sys/ioctl.h usability... yes
checking sys/ioctl.h presence... yes
checking for sys/ioctl.h... yes
checking for unistd.h... (cached) yes
checking termios.h usability... yes
checking termios.h presence... yes
checking for termios.h... yes
checking termio.h usability... yes
checking termio.h presence... yes
checking for termio.h... yes
checking return type of signal handlers... void
checking for putenv... yes
checking curses.h usability... yes
checking curses.h presence... yes
checking for curses.h... yes
checking ncurses.h usability... yes
checking ncurses.h presence... yes
checking for ncurses.h... yes
checking for tgetent in -lncurses... yes
"Using ncurses as the termcap library"
checking for use_default_colors in -lncurses... yes
checking for resizeterm in -lncurses... yes
checking for wresize in -lncurses... yes
checking for consolechars... no
checking for setfont... /bin/setfont
checking for /usr/lib/kbd/consolefonts... yes
checking for /usr/share/consolefonts... no
checking for mkfontdir... no
checking for /usr/lib/X11/fonts/misc... no
checking for /usr/X11R6/lib/X11/fonts/misc... no
configure: WARNING:
*** You do not appear to have an X window fonts directory in the standard
*** locations (/usr/lib/X11/fonts/misc or /usr/X11R6/lib/X11/fonts/misc). The
*** mtx.pcf font will not be installed. This means you will probably not
*** be able to use the mtx fonts in your x terminals, and hence be unable
*** to use the -x command line switch. Sorry about that...
checking that generated files are newer than configure... done
configure: creating ./config.status
config.status: creating Makefile
config.status: creating cmatrix.spec
config.status: creating config.h
config.status: executing depfiles commands
# make
(CDPATH="${ZSH_VERSION+.}:" && cd . && autoheader)
autoheader: WARNING: Using auxiliary files such as `acconfig.h', `config.h.bot'
autoheader: WARNING: and `config.h.top', to define templates for `config.h.in'
autoheader: WARNING: is deprecated and discouraged.
autoheader:
autoheader: WARNING: Using the third argument of `AC_DEFINE' and
autoheader: WARNING: `AC_DEFINE_UNQUOTED' allows one to define a template without
autoheader: WARNING: `acconfig.h':
autoheader:
autoheader: WARNING: AC_DEFINE([NEED_FUNC_MAIN], 1,
autoheader: [Define if a function `main' is needed.])
autoheader:
autoheader: WARNING: More sophisticated templates can also be produced, see the
autoheader: WARNING: documentation.
rm -f stamp-h1
touch config.h.in
cd . && /bin/sh ./config.status config.h
config.status: creating config.h
make all-am
make[1]: Entering directory `/root/cmatrix-1.2a'
gcc -g -O2 -o cmatrix cmatrix.o -lncurses -lncurses
make[1]: Leaving directory `/root/cmatrix-1.2a'
Type cmatrixcommand and experience matrix! You can exit out the matrix screen anytime by hitting ctlr+c on the terminal. Check cmatrix command in action in the GIF above!
Reader’s tip :
One of our readers, @Pranit Raje sent us this one-liner which did the trick. Its not as exact matrix code as we saw above but yeah it’s promising. Try and have fun in the terminal.
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.
Package naming convention
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!
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.
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 telnetcommand. 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.
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.
Small tutorial with screenshots that show how to open port on the AWS EC2 Linux server. This will help you to manage port-specific services on the EC2 server.
Open port on AWS EC2 Linux
AWS i.e. Amazon Web Services is no new term for the IT world. It’s a cloud services platform offered by Amazon. Under its Free tier account, it offers you limited services free of cost for one year. This is one of the best places to try out new technologies without spending much on the financial front.
AWS offers server computing as one of their services and they call them EC (Elastic Computing). Under this, we can build our Linux servers. We have already seen how to set up a Linux server on AWS free of cost.
By default, all Linux servers build under EC2 has post 22 i.e. SSH service port (inbound from all IP) is open only. So, if you are hosting any port-specific service then the relative port needs to be open on the AWS firewall for your server.
Also, it has port 1 to 65535 are open too (outbound for all traffic). If you want to change this you can use the same below process for editing outbound rules too.
Setting up a firewall rule on AWS for your server is an easy job. You will be able to open ports in seconds for your server. I will walk you through the procedure with screenshots to open a port for the EC2 server.
Step 1
Log in to the AWS account and navigate to the EC2 management console. Go to Security Groups under Network & Security menu as highlighted below :
AWS EC2 management console
Step 2
On Security, Groups screen select your EC2 server and under Actions menu select Edit inbound rules
AWS inbound rules menu
Step 3
Now you will be presented with an inbound rule window. You can add/edit/delete inbound rules here. There are several protocols like HTTP, nfs, etc listed in the drop-down menu which auto-populate ports for you. If you have customer service and port you can define it too.
AWS add inbound rule
For example, if you want to open port 80 then you have to select :
Type: HTTP
Protocol: TCP
Port range: 80
Source: Anywhere (Open port 80 for all incoming req from any IP (0.0.0.0/0), My IP: then it will auto-populate your current public internet IP
Step 4
That’s it. Once you save these settings your server inbound port 80 is open! you can check by telneting to port 80 for your EC2 server public DNS (can be found it EC2 server details)
Learn how to download packages from YUM or APT repository. The standalone package can be used to install on another server that has no YUM or APT configured.
Process to download package using YUM or APT
Many production environments don’t prefer to configure YUM or APT repositories on all servers. This is to avoid accidental installation of packages or up-gradating packages, which may cause issues on operations. Most of them use a centralized patch server to push updates to all servers.
If you want to install a single package on a server in such a setup, you need to have a standalone package file .rpm or .deb with you—directly downloading packages from the internet is not allowed in production areas. So you have to get packages from the server with registered YUM or APT repository configured.
The good news is you can download the package using YUM or APT! Later this package can be transferred to the intended server and can be installed. See below steps to download packages :
Download package on YUM configured server
Using downloadonly switch with yum command is a way to download packages on yum supported servers (Red Hat, CentOS). You need to fire yum install command and instruct it to download only without installing a package.
# yum install telnet --downloadonly
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
Background downloading packages, then exiting:
telnet-0.17-60.el7.x86_64.rpm | 63 kB 00:00:00
exiting because "Download Only" specified
In the above output, the install process exists since we specified download the only option (see the highlighted line).
This downloaded package (.rpm) will be saved under /var/cache/yum/<architecture>/<OS>/<repository>/packagesdirectory. A repository name can be seen in the above install command output under package details. We downloaded packages on the RHEL7 server running on x86_64 architecture. See where our package (.rpm) got downloaded :
# pwd
/var/cache/yum/x86_64/7Server/rhui-REGION-rhel-server-releases/packages
# ll
total 68
-rw-r--r--. 1 root root 64872 Nov 6 11:09 telnet-0.17-60.el7.x86_64.rpm
Alternatively, you can install yum-utils and then use the yumdownloader program to download the RPM from a repo in your PWD.
On APT supported servers like Debian, ubuntu you need to use -d option in apt-get install command.
# apt-get install -d 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.
Download complete and in download only mode
This will download package in /var/cache/apt/archives.
# pwd
/var/cache/apt/archives
# ll
total 72
drwxr-xr-x 2 root root 4096 Mar 6 11:55 ./
drwx------ 4 root root 4096 Mar 6 12:02 ../
-rw-r--r-- 1 root root 63460 May 6 2015 telnet_0.17-40_amd64.deb
----output clipped ----
Check telnet package file .deb is downloaded in the current directory. If you want to download them in the current working directory, use download option instead of install. So no hassle of tracking down the package in a variable path like yum!
# pwd
/tmp/mypackages
# apt-get download ssh
Get:1 http://ap-south-1.ec2.archive.ubuntu.com/ubuntu xenial-updates/main amd64 ssh all 1:7.2p2-4ubuntu2.1 [7,070 B]
Fetched 7,070 B in 0s (9,252 B/s)
# ll
total 16
drwxr-xr-x 2 root root 4096 May 17 10:17 ./
drwxr-xr-x 11 root root 4096 May 17 10:13 ../
-rw-r--r-- 1 root root 7070 Aug 15 2016 ssh_1%3a7.2p2-4ubuntu2.1_all.deb
You can see the ssh package got downloaded within the same working directory. Now this package can be transferred to other servers (where repositories are not configured) for installation!
Different types of package installations in Linux explained with examples. Learn package installation on a yum or apt-based system.
Package installation in Linux
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 telnetis 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.
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 :
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.
