Linux Shell Scripting – How to Read a File and Redirect to a Variable

linuxscriptingshell

I have a file with a word written on it. I want my script to put that word in a variable.

How can I do that?

in several of a million ways...

simplest is probably

my_var=$(cat my_file)

If you use bash and you want to get spiffy you can use bash4's mapfile, which puts an entire file into an array variable, one line per cell

mapfile my_var < my_file

In cross-platform, lowest-common-denominator sh you use:

#!/bin/sh
value=`cat config.txt`
echo "$value"

In bash or zsh, to read a whole file into a variable without invoking cat:

#!/bin/bash
value=$(<config.txt)
echo "$value"

Invoking cat in bash or zsh to slurp a file would be considered a Useless Use of Cat.

Note that it is not necessary to quote the command substitution to preserve newlines.