Three tricks to get two commands output in a single row. Normally two commands outputs will be always separated by a carriage return in Linux terminal.
One of the major hurdles in scripting is to get your outputs formatted well according to requirements. In Linux/Unix each command stdout its output always in a new line. This is a hurdle in many situations where the coder wants two outputs, two terms, two variables in a single row for example CSV format. In this post, we will see how to present two or more commands output in a single row.
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Normally when we execute more than one command, they will display outputs in different rows:
# date ; hostname
Sat Dec 24 01:35:50 EDT 2016
testsrv2
# echo text1; echo text2; echo text3
text1
text2
text3
In the above example, commands have outputs per row. We are going to accomplish all outputs in one row using the below tricks.
Trick 1:
Using the translate function. AS I said earlier each command output is accompanied by a carriage return. We will be translating carriage return with tab character hence getting two or more commands output in a single row.
# (date; hostname) |tr '\n' '\t'
Sat Dec 24 01:36:22 EDT 2016 testsrv2
# (echo text1; echo text2; echo text3) |tr '\n' '\t'
text1 text2 text3
Bypassing outputs to translate function we achieved single row output. Here we instructed tr function to translate all carriage returns (\n) to tab (\t).
If you want to output in CSV format (comma-separated value) then replace tab with a comma and you will get it.
# (date; hostname) |tr '\n' ','
Sat Dec 24 01:43:09 EDT 2016,testsrv2,
# (echo text1; echo text2; echo text3) |tr '\n' ','
text1,text2,text3,
You can observe one trailing comma which shows every command output ends with \n and hence it gets replaced by ,
Trick 2:
By defining each command output as a variable. Here we will store the output of each command in one variable and then we will echo those variables in a single line.
# mydate=`date`
# myname=`hostname`
# echo $myname $mydate
testsrv2 Sat Dec 24 01:46:04 EDT 2016
Here we stored date and hostname command’s output in mydate and myname variables. In the last command, we echoed both variables with space in between. Note that commands output can be stored in a variable by executing the command using backticks (in-line execution)!
Trick 3:
By echoing in-line execution outputs. In-line execution i.e. using backticks to execute commands within another command. We will be using this trick to echo outputs in a single row.
# echo "`date` `hostname`"
Sat Dec 24 01:50:36 EDT 2016 testsrv2
In the above example, first, we have executed commands and got outputs. But those outputs are fed into echo command. Hence echo command stdout them in a single row.
# echo "`echo text1` `echo text2` `echo text3`"
text1 text2 text3
Make a note that we executed each command in separate back tick quotes.