[Klug-general] Cron job

[Jeremy Hooks]

2009/4/9 Nathan Friend <nathan.friend at gmail.com>:
> Afternoon All,
> I've writen a simple script to dump a database and would like it to run as a
> cron job.  How should I set the script permisisons?

Presuming the cron job is being run by root you will probably want to
make sure the script is owned by root:
chown root.root /usr/local/script/dbbackup.sh

Then you can set the permissions with so that only root has
permissions to read/write/execute it:
chmod 700 /usr/local/script/dbbackup.sh
or
chmod u=rwx /usr/local/script/dbbackup.sh

> dbbackup.sh contains:
>
> NOW=$(date +"%d-%b-%y"_"%l:%M")
> FILENAME="moodle_db_backup_$NOW.sql"
> mysqldump -uuser -ppassword databasename > /dbbck/$FILENAME

Don't forget, ofcourse if you want the script to actually run you need
a shebang too, e.g.:
#!/usr/bin/bash

The date format you are using will likely cause you problems as it
will give you something like "09-Apr-09_ 8:30", a filename with a
space in it.  With either a %I (12 hour, with leading zero) or %H (24
hour, with leading zero) rather than %l (12 hour, leading space).
Something else that is important to remember when writing cron scripts
is that you can't always be certain that the path variable isn't
necessarily the same as you would have when running running the script
from an interactive shell.  So I would recommend changing 'mysqldump'
to '/fullpath/mysqldump'.


> The cron entry is
>
> 30 20 * * * /usr/local/script/dbbackup.sh
>
> I can run the script from for command line OK with the expected output.
> However wathcing /var/log/messages I see the cron job run but no output
> file...

One final thing, if your script running but you aren't getting the
results you expect, it may be worth checking the output of the
command.  Normally the output from cron scripts is emailed to the user
using the local mail system.  You can check this by using (say) mutt
or 'vi /var/spool/mail/root'.

I think that is everything, but I don't use cron often, so I could
have forgotten something.

Regards.

Jeremy