When you run a command, it produces some kind of output: either the result of a program is suppose to produce or status/error messages of the program execution details. Sometimes, you may want to store the output of a command in a variable to be used in a later operation.
In this post, we will review the different ways of assigning the output of a shell command to a variable, specifically useful for shell scripting purpose.
To store the output of a command in a variable, you can use the shell command substitution feature in the forms below:
Below are a few examples of using command substitution.
In this first example, we will store the value of`who`(which shows who is logged on the system) command in the variable`CURRENT_USERS`user:
```
$ CURRENT_USERS=$(who)
```
Then we can use the variable in a sentence displayed using the[echo command][1]like so:
```
$ echo -e "The following users are logged on the system:\n\n $CURRENT_USERS"
```
In the command above: the flag`-e`means interpret any escape sequences ( such as`\n`for newline) used. To avoid wasting time as well as memory, simply perform the command substitution within the[echo command][2]as follows:
```
$ echo -e "The following users are logged on the system:\n\n $(who)"
```
[
][3]
Shows Current Logged Users in Linux
Next, to demonstrate the concept using the second form; we can store the total number of files in the current working directory in a variable called`FILES`andechoit later as follows:
```
$ FILES=`sudo find . -type f -print | wc -l`
$ echo "There are $FILES in the current working directory."
```
[
][4]
Show Number of Files in Directory
That’s it for now, in this article, we explained the methods of assigning the output of a shell command to a variable. You can add your thoughts to this post via the feedback section below.
Aaron Kili is a Linux and F.O.S.S enthusiast, an upcoming Linux SysAdmin, web developer, and currently a content creator for TecMint who loves working with computers and strongly believes in sharing knowledge.
