Crontab not writing a command to a log file

JockVSJock · 03-03-2016, 12:48 PM

I have the following cron job who goal is to show disk free on a server at 12:01 am each day. Also want to write a time/date stamp to the log, because we are wanting to watch disk size grow. However it isn't writing anything to the following df.log file at all.

Code:

1 0 * * * /bin/df -ha > /root/output/df/`date +\%Y\%m\%d\%H\%M%\S\ -df.log 2>&1

I've even modified the crontab so it will run every 5 minutes, however nothing.

And to troubelshoot, I've removed 2>&1, yet still nothing getting written to that log.

Any recommendations on how to fix this?

thanks

thesnow · 03-03-2016, 01:13 PM

You're missing the end backquote, but even if you put it in there before "-df" it is escaped by the preceding backslash. You may also need the full path to "date". This works for me:

Code:

/bin/df -ha > /root/output/df/`/bin/date "+\%Y\%m\%d\%H\%M\%S"`-df.log 2>&1

JockVSJock · 03-03-2016, 01:53 PM

I made the changes you recommended, set the crontab to run every 1 minute to test and still not working.

I'm looking thru /var/log/cron and don't see anything that stands out...

hydrurga · 03-03-2016, 02:04 PM

Quote:

Originally Posted by JockVSJock

I made the changes you recommended, set the crontab to run every 1 minute to test and still not working.

I'm looking thru /var/log/cron and don't see anything that stands out...

Just for info, as a one-off command, thesnow's suggestion works for me. Have you tried it as a one-off command to take cron out of the equation?

suicidaleggroll · 03-03-2016, 02:16 PM

How about removing all of the date stuff, does that run?

Code:

1 0 * * * /bin/df -ha > /root/output/df/test.log 2>&1

Habitual · 03-03-2016, 02:48 PM

Quote:

Originally Posted by thesnow

Code:

/bin/df -ha > /root/output/df/`/bin/date "+\%Y\%m\%d\%H\%M\%S"`-df.log 2>&1

or

Code:

/bin/df -ha > /root/output/df/$(/bin/date "+\%Y\%m\%d\%H\%M\%S")-df.log 2>&1

but you really, really, really want

Code:

/root/output/df/\2016\03\03\15\44\24-df.log

as the output?

Code:

echo /root/output/df/$(/bin/$(date "+%Y-%m-%d-%H-%M-%S")-df.log

is readable, and cleaner?
If you agree, try

Code:

/bin/df -ha > /root/output/df/$(date "+%Y-%m-%d-%H-%M-%S")-df.log 2>&1

which gives

Code:

/root/output/df/2016-03-03-15-45-40-df.log

suicidaleggroll · 03-03-2016, 04:04 PM

Quote:

Originally Posted by Habitual

but you really, really, really want

Code:

/root/output/df/\2016\03\03\15\44\24-df.log

as the output?

Code:

echo /root/output/df/$(/bin/$(date "+%Y-%m-%d-%H-%M-%S")-df.log

is readable, and cleaner?

Cron uses the delimiters to pass a literal "%" to date. You only see them when you run date on the command line, when you run it through cron they disappear. Without them you'll get errors out the wazoo from cron when it tries to run the command.

JockVSJock · 03-04-2016, 08:38 AM

Quote:

Originally Posted by suicidaleggroll

How about removing all of the date stuff, does that run?

Code:

1 0 * * * /bin/df -ha > /root/output/df/test.log 2>&1

Yes it did run at 00:01, the time I want, so that is good.

However I did what Habitual recommended and rolled the time back on the crontab to every minute and still didn't write to that log.

However I ran the following from the CLI:

Code:

/bin/df -ha > /root/output/df/$(date "+%Y-%m-%d-%H-%M-%S")-df.log 2>&1

The weird thing is that it didn't write to df.log however it created the following file: 2016-03-04-08-33-33-df.log. I'm not sure why it didn't write to the df.log file Vs creating a new file.

suicidaleggroll · 03-04-2016, 09:39 AM

Quote:

Originally Posted by JockVSJock

Yes it did run at 00:01, the time I want, so that is good.

That's good

Quote:

Originally Posted by JockVSJock

However I did what Habitual recommended and rolled the time back on the crontab to every minute and still didn't write to that log.

What makes you think that?

Quote:

Originally Posted by JockVSJock

However I ran the following from the CLI:

Code:

/bin/df -ha > /root/output/df/$(date "+%Y-%m-%d-%H-%M-%S")-df.log 2>&1

it created the following file: 2016-03-04-08-33-33-df.log.

Good

Quote:

Originally Posted by JockVSJock

I'm not sure why it didn't write to the df.log file Vs creating a new file.

Because that's what you told it to do. What did you think "command > /root/output/df/$(date "+%Y-%m-%d-%H-%M-%S")-df.log" was supposed to do if not write the output of the command to a dynamic filename using the current system date/time???