Chthontab

Chthontab is the name of the Linux program that inhabitants of the underworld user to schedule their tasks.

Thank you. I'm here * * * * 0-6.

Crontab format (V3)

MAILTO=me@there.co.uk

# minute (0-59),
# | hour (0-23),
# | | day of the month (1-31),
# | | | month of the year (1-12),
# | | | | day of the week (0-6 with 0=Sunday).
# | | | | | commands
# 3 2,3,4 * * 0,6 /command to run on more than one day/hour
# 3 2,4-7 * * 1-5 /another/command to run on a range of days/hours

04 10 * * * /command/here 2>> /path/to/log/prog.$(date +\%Y\%m\%d).log

NOTES:

• You must escape percent signs with a backslash
• Putting them in double quotes doesn't work
• Putting in double quotes and backslashes works, but the backslashes are written as part of the filename. So don't so that.
  

Email output from the crontab

method 1 - for all commands

Add this as the first line of crontab:

MAILTO=address1@host.com,address2@host.co.uk

method 2 - for specific commands

Add this line anywhere near the top:

NOTIFY_LIST="address1@host.com,address2@host.co.uk"

Use this for the command:

00 09 * * * run_command | mail -s "command has run" $NOTIFY_LIST

Errors in crontab

When your clever crontab entry doesn't work:

/bin/sh: -c: line 0: unexpected EOF while looking for matching `"'

/bin/sh: -c: line 1: syntax error: unexpected end of file

You might need to escape some characters, like the percent sign: \%

Also consider that the backslash may not have the desired effect if it's inside double quotes.