How to read a file into a variable in shell?

Question

I want to read a file and save it in variable, but I need to keep the variable and not just print out the file. How can I do this? I have written this script but it isn't quite what I needed:

#!/bin/sh while read LINE   do     echo $LINE   done <$1   echo 11111-----------   echo $LINE   

In my script, I can give the file name as a parameter, so, if the file contains "aaaa", for example, it would print out this:

aaaa 11111----- 

But this just prints out the file onto the screen, and I want to save it into a variable! Is there an easy way to do this?

Answer 1

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.

See: Bash Hacker's Wiki - Command substitution - Specialities.

Answer 2

If you want to read the whole file into a variable:

#!/bin/bash value=`cat sources.xml` echo $value 

If you want to read it line-by-line:

while read line; do         echo $line     done < file.txt