Shell Script, Saving the Command Value to a Variable

Shell script, saving the command value to a variable

use backticks (or $() – can be nested), not single quotes:

VARI=`cat filename | head -1 | cut -d, -f${i}` # or:
VARI=$(cat filename | head -1 | cut -d, -f${i})

How to store an output of shell script to a variable in Unix?

Two simple examples to capture output the pwd command:

$ b=$(pwd)
$ echo $b
/home/user1

or

$ a=`pwd`
$ echo $a
/home/user1

The first way is preferred. Note that there can't be any spaces after the = for this to work.

Example using a short script:

#!/bin/bash

echo "hi there"

then:

$ ./so.sh
hi there
$ a=$(so.sh)
$ echo $a
hi there

In general a more flexible approach would be to return an exit value from the command and use it for further processing, though sometimes we just may want to capture the simple output from a command.

How do I set a variable to the output of a command in Bash?

In addition to backticks `command`, command substitution can be done with $(command) or "$(command)", which I find easier to read, and allows for nesting.

OUTPUT=$(ls -1)
echo "${OUTPUT}"

MULTILINE=$(ls \
   -1)
echo "${MULTILINE}"

Quoting (") does matter to preserve multi-line variable values; it is optional on the right-hand side of an assignment, as word splitting is not performed, so OUTPUT=$(ls -1) would work fine.

Store value to variable in Shell script

You have to use the right quotation, like this:

total_rows=`echo "$emails" | ./jq '.total_rows'`

The `` will execute the command and give total_rows the value of it, so whatever would be the output of

echo "$emails" | ./jq '.total_rows'

will so be stored in total_rows.

As mentioned in the comments by Tom Fenech, it is better to use $() for command substitution. It provides a better readability. So what you can do is:

total_rows=$(echo "$emails" | ./jq '.total_rows')

How can I store a command in a variable in a shell script?

Use eval:

x="ls | wc"
eval "$x"
y=$(eval "$x")
echo "$y"

shell script can not save output from command line into variable

You have a space before your equals sign:

out =`python --version`

Should be:

out=`python --version`

Update

Also python outputs the version string to stderr, so you need to redirect it to stdout:

out=`python --version 2>&1`

Shell: save ssh command result to local variable

Your command should be wrapped in "()" not "{}" when assigning fetching the result to a variable. Also, the others are just variables not commands so don't need a wrapper (assuming they are defined in a script or something).

lines=$(ssh $user@$hostname "wc -l < $workspace/logs")

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