Environmental Variables Not Seen in a Cron

Where can I set environment variables that crontab will use?

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

crontab not getting my current envrioment variables

You can assign your environment variables into the crontab environment file (crontab -e) so I convert all my environment variables into an env.txt and merge the crontab environment file into that env.txt file and replace the crontab environment file with my env.txt.

crontab -e default:

0 */24 * * * /usr/local/bin/python /app/manage.py crontab run 5d758d881d8f93b61f4d1b6a43eb72f6 >> /cron/django_cron.log 2<&1 # django-cronjobs for app

if you assign some VARIABLE in that file like below so the crontab will get that environment.

VARIABLE=value
0 */24 * * * /usr/local/bin/python /app/manage.py crontab run 5d758d881d8f93b61f4d1b6a43eb72f6 >> /cron/django_cron.log 2<&1 # django-cronjobs for app

here is the bash command to achieve it

$ printenv > env.txt # this will add all your environment variables in to env.txt
$ cat /var/spool/cron/crontabs/root >> env.txt # this will merge crontab environment file with your env.txt
$ cat env.txt > /var/spool/cron/crontabs/root # this will replace the crontab environment file with your env.txt

that's the only solution I produce on my own, hopefully, it will help you guys. thanks