Echo bash variable in separate bash process

Question

I'm trying to create a separate bash process and echo a variable which is set inside of it with no success. Nothing gets echoed.

bash -c "COMMIT_DIFF_FILE=diffs.diff && echo -e ${COMMIT_DIFF_FILE}"

What could be the problem here? Many thanks in advance!

as far as I understand, export can be used to inject a variable into the environment. Here, I'm creating a separate process which sets a new variable and then echos it. — Mihai Galos, Dec 12 '18 at 08:08
`export` makes the variable available to sub-processes. BTW, I got there's a [thread](https://stackoverflow.com/questions/1158091/defining-a-variable-with-or-without-export) with more info! — trinaldi, Dec 12 '18 at 08:09

score 1 · Accepted Answer · answered Dec 12 '18 at 08:13

You have to quote it right.

bash -c 'COMMIT_DIFF_FILE="diffs.diff" && echo "$COMMIT_DIFF_FILE"'

diffs.diff

You are quoting command to bash -c in double quotes which gets expanded in current shell where variable is not present.

If you want to use double quotes then escape $:

bash -c "COMMIT_DIFF_FILE=diffs.diff && echo \${COMMIT_DIFF_FILE}"

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