Replace string in another file with sed from bash script

Question

I'm trying to replace the value of an environment variable definition, if it exists, from a bash script. I know I can use sed to do this, I'm not sure, however, how to replace the value of the environment variable?

Here's what I'd like to do:

Given a file with this line (found with grep):

export MY_ENV=SOME_VALUE

I'd like to replace SOME_VALUE with something else. How do I do that with sed?

bmk · Accepted Answer · 2011-05-19 13:00:00Z

5

This searches for the line beginning with export MY_ENV= and substitutes the rest of the line with NEW_VALUE:

sed 's/^\(export MY_ENV=\).*$/\1NEW_VALUE/'

answered May 19, 2011 at 13:00

bmk

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1 Comment

sastanin Over a year ago

Also, sed -i will modify the file in-place.

Jonathan Leffler · Accepted Answer · 2011-05-19 12:58:24Z

0

sed -e "s/SOME_VALUE/$MY_ENV/"

This locates the string SOME_VALUE and substitutes the value of $MY_ENV. The double quotes are crucial; don't use single quotes unless you want $, M, Y, ... in the replacement text.

answered May 19, 2011 at 12:58

Jonathan Leffler

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