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Frank Vilea
Asked: 2011-09-30 03:49:18 +0800 CST

Can't get cron.hourly to work

  • 772

I installed cron with sudo apt-get install cron, started it as root and confirmed that it is running with 

ps -ef

I then created a simple script with the following contents:

touch /home/username/cron-test.txt

I made this script file executable and put it into

mv cron-test.sh /etc/cron.hourly

For some reason though, it does not get executed and the file is not being created. I tried running it manually and it works.

I also tried other cron scripts and they do not seem work. Did I miss something or am I using cron incorrectly?

My system is Ubuntu 10.10 and my hoster has stripped it down so it came with only a few processes installed (not even cron).

ubuntu cron

2 Answers

  1. Best Answer

    Try adding #! /bin/sh as the first line of your script and removing the extension, so that the name is /etc/cron.hourly/cron-test

    I remember reading somewhere that cron will not run files with an extension, because it uses runparts when /ect/crontab has the following contents:

    # /etc/crontab: system-wide crontab
# Unlike any other crontab you don't have to run the `crontab'
# command to install the new version when you edit this file
# and files in /etc/cron.d. These files also have username fields,
# that none of the other crontabs do.

SHELL=/bin/sh
PATH=/usr/local/sbin:/usr/local/bin:/sbin:/bin:/usr/sbin:/usr/bin

# m h dom mon dow user  command
17 *    * * *   root    cd / && run-parts --report /etc/cron.hourly
25 6    * * *   root    test -x /usr/sbin/anacron || ( cd / && run-parts --report /etc/cron.daily )
47 6    * * 7   root    test -x /usr/sbin/anacron || ( cd / && run-parts --report /etc/cron.weekly )
52 6    1 * *   root    test -x /usr/sbin/anacron || ( cd / && run-parts --report /etc/cron.monthly )

    The above is the content of my /etc/crontab on Ubuntu 10.04, with cron installed (I have not edited this file)

    Since the /etc/crontab file uses run-parts, filename are very restrictive as per (Thanks Matteo):

    run-parts runs a number of scripts or programs found in a single directory 
directory. Filenames should consist entirely of upper and lower case letters,
digits, underscores, and hyphens. Subdirectories of directory and files with
other names will be silently ignored. Scripts must follow the
#!/bin/interpretername convention in order to be executed. They will not
automatically be executed by /bin/sh. The files found will be run in the
lexical sort order of the filenames.
    • 10

  2. Here's a quote from the run-parts man page:

    Filenames should consist entirely of upper and lower case letters, digits, underscores, and hyphens.

    The thing is, you've included a '.' in your filename (just before the 'txt'). That period doesn't match the filename pattern that run-parts uses to find scripts.

    Remember that file extensions are NOT part of the filesystem! Any file extensions you put on are simply part of the filename, and so when the rules say 'filename', that includes the period and the extensions.

    Further,

    Scripts must follow the #!/bin/interpretername convention in order to be executed.

    Which means that you MUST put in the #!/bin/bash in order for your script to be executed.

    • 4