Question

I’m using a mini shell script in order to ‘tail’ (in real time) a bunch of log files.

#!/bin/sh

oldGLOBIGNORE=$GLOBIGNORE

export GLOBIGNORE='foo-bar.log'

sudo -E tail -f -n0 /var/log/*.log

GLOBIGNORE=$oldGLOBIGNORE

As you can see, I want to log all files except the one named foo-bar.log.

the -E option of sudo should allow me to keep the GLOBIGNORE variable but it looks like it does not work.

I’m testing on Ubuntu 10.04, bash 4.1.5.

Any clue ?

Answer 1

Firstly — GLOBIGNORE relates to the full filepath resulting from filename-expansion, not just the last part. So you actually want to write GLOBIGNORE='/var/log/foo-bar.log'.

Secondly — you don’t actually need to export GLOBIGNORE into the environment and add -E, because the /var/log/*.log gets expanded by Bash before it even invokes sudo.

Thirdly — your approach to saving the old value of GLOBIGNORE and restoring it afterward is less than ideal, because the behavior when GLOBIGNORE is unset is different from its behavior when it’s set-but-empty, and your script can never restore it to being unset. Fortunately, the script doesn’t need to restore it (since it’s not as though a script’s variables could continue to have effect after the script returns), so you can just remove that stuff.

All told, you can write:

#!/bin/sh

GLOBIGNORE=/var/log/foo-bar.log
sudo tail -f -n0 /var/log/*.log