[GRLUG] using flock

[Michael Glaske]

Exactly.  You can also >> that out to a log file so you can tell
what's going on.  Trap is a good idea too.

Sent from my iPhone

> On Dec 24, 2013, at 9:32 AM, Eric Beversluis <ebever at researchintegration.org> wrote:
>
> Thanks.
> So since the script started and then exits, cron assumes it has run and
> just waits till the next time?
>
>> On Tue, 2013-12-24 at 09:25 -0500, Michael Glaske wrote:
>> Pretty easy to implement in bash or sh..  The only problem is, if you
>> Crtl-C out of it, you'll have to manually remove the lock file.
>>
>>
>> if [ -f /var/run/script.lock ]; then
>>     print "Already running..  Exiting"
>>     exit 1
>> fi
>>
>>
>> date > /var/run/script.lock
>>
>>
>> # put your script here
>>
>>
>> # at the end
>> rm -f /var/run/script.lock
>>
>>
>> On Tue, Dec 24, 2013 at 9:17 AM, Eric Beversluis
>> <ebever at researchintegration.org> wrote:
>>        I've got a backup program on a server that includes a
>>        mysqldump once a
>>        day which overwrites the existing sysmyqldump.sql. The script
>>        also does
>>        rsync (of zarafa-backup, the mysqldump, and /var/lib/zarafa
>>        (the zarafa
>>        attachments file) to an external hard drive. Once a month is
>>        also copies
>>        the sysmysqldump.sql that's on the external HDD to a file with
>>        that
>>        day's date attached.
>>
>>        The cron is set to run every hour. Right now, mysqldump is
>>        finishing at
>>        40 min past the hour (00:40), so I think that when it also
>>        tries to make
>>        the copy on the 1st of the month it will run over into the
>>        next hour.
>>
>>        As I understand it, the thing to do to prevent the script
>>        starting over
>>        before the old one finishes is to use 'flock.'
>>
>>        My question is this: How does cron respond if flock prevents
>>        the script
>>        from starting at 01:00? Does it start it when the flock is
>>        freed or just
>>        skip that cycle or what?
>>
>>        Thanks.
>>
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