Where can I set environment variables that crontab will use?

Question

I have a crontab running every hour. The user running it has environment variabless in the .bash_profile that work when the user runs the job from the terminal,

Answer 1

Have 'cron' run a shell script that sets the environment before running the command.

Always.

#   @(#)$Id: crontab,v 4.2 2007/09/17 02:41:00 jleffler Exp $
#   Crontab file for Home Directory for Jonathan Leffler (JL)
#-----------------------------------------------------------------------------
#Min     Hour    Day     Month   Weekday Command
#-----------------------------------------------------------------------------
0        *       *       *       *       /usr/bin/ksh /work1/jleffler/bin/Cron/hourly
1        1       *       *       *       /usr/bin/ksh /work1/jleffler/bin/Cron/daily
23       1       *       *       1-5     /usr/bin/ksh /work1/jleffler/bin/Cron/weekday
2        3       *       *       0       /usr/bin/ksh /work1/jleffler/bin/Cron/weekly
21       3       1       *       *       /usr/bin/ksh /work1/jleffler/bin/Cron/monthly

The scripts in ~/bin/Cron are all links to a single script, 'runcron', which looks like:

:       "$Id: runcron.sh,v 2.1 2001/02/27 00:53:22 jleffler Exp $"
#
#       Commands to be performed by Cron (no debugging options)

#       Set environment -- not done by cron (usually switches HOME)
. $HOME/.cronfile

base=`basename $0`
cmd=${REAL_HOME:-/real/home}/bin/$base

if [ ! -x $cmd ]
then cmd=${HOME}/bin/$base
fi

exec $cmd ${@:+"$@"}

(Written using an older coding standard - nowadays, I'd use a shebang '#!' at the start.)

The '~/.cronfile' is a variation on my profile for use by cron - rigorously non-interactive and no echoing for the sake of being noisy. You could arrange to execute the .profile and so on instead. (The REAL_HOME stuff is an artefact of my environment - you can pretend it is the same as $HOME.)

So, this code reads the appropriate environment and then executes the non-Cron version of the command from my home directory. So, for example, my 'weekday' command looks like:

:       "@(#)$Id: weekday.sh,v 1.10 2007/09/17 02:42:03 jleffler Exp $"
#
#       Commands to be done each weekday

# Update ICSCOPE
n.updics

The 'daily' command is simpler:

:       "@(#)$Id: daily.sh,v 1.5 1997/06/02 22:04:21 johnl Exp $"
#
#       Commands to be done daily

# Nothing -- most things are done on weekdays only

exit 0