[bash] File content into unix variable with newlines

I have a text file test.txt with the following content:

text1
text2 

And I want to assign the content of the file to a UNIX variable, but when I do this:

testvar=$(cat test.txt)
echo $testvar

the result is:

text1 text2

instead of

text1
text2 

Can someone suggest me a solution for this?

The envdir utility provides an easy way to do this. envdir uses files to represent environment variables, with file names mapping to env var names, and file contents mapping to env var values. If the file contents contain newlines, so will the env var.

See https://pypi.python.org/pypi/envdir

This is due to IFS (Internal Field Separator) variable which contains newline.

$ cat xx1
1
2

$ A=`cat xx1`
$ echo $A
1 2

$ echo "|$IFS|"
|       
|

A workaround is to reset IFS to not contain the newline, temporarily:

$ IFSBAK=$IFS
$ IFS=" "
$ A=`cat xx1` # Can use $() as well
$ echo $A
1
2
$ IFS=$IFSBAK

To REVERT this horrible change for IFS:

IFS=$IFSBAK

Your variable is set correctly by testvar=$(cat test.txt). To display this variable which consist new line characters, simply add double quotes, e.g.

echo "$testvar" 

Here is the full example:

$ printf "test1\ntest2" > test.txt
$ testvar=$(<test.txt)
$ grep testvar <(set)
testvar=$'test1\ntest2'
$ echo "$testvar"
text1
text2
$ printf "%b" "$testvar"
text1
text2

Just if someone is interested in another option:

content=( $(cat test.txt) )

a=0
while [ $a -le ${#content[@]} ]
do
        echo ${content[$a]}
        a=$[a+1]
done

Bash -ge 4 has the mapfile builtin to read lines from the standard input into an array variable.

help mapfile 

mapfile < file.txt lines
printf "%s" "${lines[@]}"

mapfile -t < file.txt lines    # strip trailing newlines
printf "%s\n" "${lines[@]}" 

See also:

http://bash-hackers.org/wiki/doku.php/commands/builtin/mapfile