Tom Badran wrote:
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> How can i use an if in a bash script so that it will only run commands if the
> specified file is empty?
>
> Basically, ive set up a cache system by which the output of ifconfig is
> stored in /var/cache/IP/1
>
> Then, every minute my script is run. It first puts the output of ifconfig in
> /var/cache/IP/2 and diff's it with 1 outputing that to a file 'diff'. I then
> want to run a series of commands if the file diff is not empty.
>
Well first, you can test the exit value of diff to see if there
were differences:
if diff /var/cache/IP/1 /var/cache/IP/2; then
#commands for when files are the same
else
#commands for when files differ
fi
Or if you only care when they differ:
if ! diff /var/cache/IP/1 /var/cache/IP/2; then
#commands for when files differ
fi
If you really need to test for empty files, try:
if [ -s filename ]; then
#commands for when file is *not* empty
else
#commands for when file is empty
fi
Or if you only care for the empty ones:
if [ ! -s filename ]; then
#commands for when the file is empty
fi
-Kyle
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