How can one store a variable in a file using bash?

Question

I can redirect the output and then cat the file and grep/awk the variable, but I would like to use this file for multiple variables.

So If it was one variable say STATUS then i could do some thing like

echo "STATUS $STATUS" >> variable.file
#later perhaps in a remote shell where varible.file was copied
NEW_VAR=`cat variable.file | awk print '{$2}'`

I guess some inline editing with sed would help. The smaller the code the better.

Answer 1

One common way of storing variables in a file is to just store NAME=value lines in the file, and then just source that in to the shell you want to pick up the variables.

echo 'STATUS="'"$STATUS"'"' >> variable.file
# later
. variable.file

In Bash, you can also use source instead of ., though this may not be portable to other shells. Note carefully the exact sequence of quotes necessary to get the correct double quotes printed out in the file.

If you want to put multiple variables at once into the file, you could do the following. Apologies for the quoting contortions that this takes to do properly and portably; if you restrict yourself to Bash, you can use $"" to make the quoting a little simpler:

for var in STATUS FOO BAR
do
    echo "$var="'"'"$(eval echo '$'"$var")"'"'
done >> variable.file

Answer 2

The declare builtin is useful here

for var in STATUS FOO BAR; do
    declare -p $var | cut -d ' ' -f 3- >> filename
done

As Brian says, later you can source filename

declare is great because it handles quoting for you:

$ FOO='"I'"'"'m here," she said.'
$ declare -p FOO
declare -- FOO="\"I'm here,\" she said."
$ declare -p FOO | cut -d " " -f 3-
FOO="\"I'm here,\" she said."