Find and replace text within a file on OSX/bash

Question

I am trying to replace the text within a file with the contents of a variable $ourpath, so that a directory path is replaced.

    sed -e "s/__REPLACE_THIS_PATH__/${ourpath}/" com.plex.plexconnect_daemon.bash.plist  > com.plex.plexconnect_daemon.bash.plist

but when i run this, it just deletes the contents of the file, or is overwriting it with a zero length file.

any thoughts?

Variables are not expanded inside single quotes, only double quotes. This is basic shell scripting. — Barmar
– Barmar, Commented Nov 14, 2013 at 6:25
my bad, i had double quotes in my original script. i just saw something on a web page which had single which i tried. i forgot to change back. question is now updated. thanks for the headsup. but it still doesn't work with the double quotes. — user2990773
– user2990773, Commented Nov 14, 2013 at 6:33

Barmar · Accepted Answer · 2013-11-14 06:36:00Z

2

You can't redirect output to the input file. When the redirection happens, the file is truncated, so there's nothing to read from. Either write to a different file and then rename it, or use the -i option to sed:

sed -i.bak -e "s/__REPLACE_THIS_PATH__/${ourpath}/" com.plex.plexconnect_daemon.bash.plist

This will add the .bak suffix to the original file and put the result in a new file with the original name.

answered Nov 14, 2013 at 6:36

Barmar

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4 Comments

user2990773 Over a year ago

could i write the new file to a different folder? in which case, how would that look? my code below doesn't seem to work

sed -i -e "s/__REPLACE_THIS_PATH__/${ourpath}/" ./com.plex.plexconnect_daemon.bash.plist > /Library/LaunchDaemons/com.plex.plexconnect_daemon.bash.plist

rojomoke Over a year ago

If you're using -i you don't need the redirect: sed -i -e "s/__REPLACE_THIS_PATH__/${ourpath}/" ./com.plex.plexconnect_daemon.bash.plist

user2990773 Over a year ago

what if i wanted to have the updated file located in a different folder, leaving the original untouched?

Barmar Over a year ago

Then you do it like in your original code, with redirection. The only special case is when you want to overwrite the original file.

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