30 10 | 2013

Beware of symlinks when testing a file existence

Written by Tanguy

Classified in : Debian, Command line, To remember

A strange problem

Yesterday, I was reported a funny problem with the dokuwiki Debian package's postinst script, which contains a piece of shell script similar to that:

# Check the destination does not already exist
if [ ! -e /the/destination ]
then
    ln -s /some/file /the/destination
fi

It was failing with that message: ln: failed to create symbolic link '/the/destination': File exists. Even though I had just tested it did not exist!

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