Stuck on an IF!

[Torquemada]

Hi everybody

after years of programming on windows I started to write some scripts on linux, and I'm stuck on a IF! I feel so rookie....

if ['date +%u'=5]; then
tar "full"
else
tar "incremental"
fi

I'd like to make a full backup on th 5th day of the week, and incremental all the others.
Where I do wrong?!?!

[wje_lf]

In that first line, use backticks. Also, make sure your left square bracket is followed by a space and your right square bracket is preceded by a space.

if [ `date +%u`=5 ]; then

Those backticks look far too much like regular single quotes. For that reason, I'd recommend the $(whatever) syntax:

if [ $(date +%u)=5 ]; then

Hope this helps.

[scm]

Why not use cron to make that decision?

[Torquemada]

thanks I've solved the problem
cron fires do_backup `date +%u` and inside the script the check is "if [ $1 = 5 ]"...

[scm]

An alternative way would be to have two cron entries - one with "5" in the 5th field to do the full backup and the other with "0-4,6" to do the incremental backup. Give the script a "full" or "inc" argument to switch. It's a close call in your specific application as to which is the most effective, but for some apps letting cron decide on the day is neater.

[Torquemada]

An alternative way would be to have two cron entries - one with "5" in the 5th field to do the full backup and the other with "0-4,6" to do the incremental backup. Give the script a "full" or "inc" argument to switch. It's a close call in your specific application as to which is the most effective, but for some apps letting cron decide on the day is neater.

that was my previus configuration, but now I need a script where I can write just once all the backup commands as they change often and I prefer not to be forced to put changes in two files.
However now the script is ok! cron fires "do_backup `date +%u`" and the script has an if with $1, if it's not 5 it adds "- newer..." to tar options.
Thanks a lot to everyone!