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--- ubuntu:bash:assign_output_of_shell_command_to_variable [2019/11/28 23:15] – peter
+++ ubuntu:bash:assign_output_of_shell_command_to_variable [2019/12/07 01:33] (current) – removed peter
@@ Line 1: / Line 1: @@
-====== Ubuntu - BASH - Assign Output of Shell Command To Variable ======
-To assign output of any shell command to variable in bash, use the following command substitution syntax:
-<code bash>
-var=$(command-name-here)
-var=$(command-name-here arg1)
-var=$(/path/to/command)
-var=$(/path/to/command arg1 arg2)
-</code>
-OR use backticks based syntax as follows to assign output of a Linux command to a variable:
-<code bash>
-var=`command-name-here`
-var=`command-name-here arg1`
-var=`/path/to/command`
-var=`/path/to/command arg1 arg2`
-</code>
-Do not put any spaces after the equals sign and command must be on right side of =.
-----
-===== Examples =====
-To store date command output to a variable called now, enter:
-## store date command output to $now  ##
-<code bash>
-now=$(date)
-</code>
-OR
-## alternate syntax ##
-<code bash>
-now=`date`
-</code>
-----
-To display back result (or output stored in a variable called $now) use the echo or printf command:
-<code bash>
-echo "$now"
-printf "%s\n" "$now"
-</code>
-Sample outputs:
-<code bash>
-Wed Apr 25 00:55:45 IST 2012
-</code>
-----
-You can combine the echo command and shell variables as follows:
-<code bash>
-echo "Today is $now"
-</code>
-Sample outputs:
-<code bash>
-Today is Wed Apr 25 00:55:45 IST 2012
-</code>
-----
-You can do command substitution in an echo command itself (no need to use shell variable):
-<code bash>
-echo "Today is $(date)"
-printf "Today is %s\n" "$(date)"
-</code>
-Sample outputs:
-<code bash>
-Today is Wed Apr 25 00:57:58 IST 2011
-</code>
-----
-===== Use Multiline Command =====
-Try the following syntax:
-<code bash>
-my_var=$(command \
-arg1 \
-arg2 \
-arg3 )
-echo "$my_var"
-----
-===== Example using Date =====
-<code bash>
-OUT=$(date \
---date='TZ="America/Los_Angeles" 09:00 next Thu')
-echo "$OUT"
-<code bash>
-----
-===== Example using Ping =====
-<code bash>
-#!/bin/bash
-_ping="/bin/ping"
-domain="www.cyberciti.biz"
-ping_avg="$(${_ping} \
--q \
--c 4 \
-${domain} | grep rtt)"
-echo "Avg ping time for ${domain} : ${ping_avg}"
-</code>