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Old 10-06-2003, 05:01 AM   #1
Registered: Oct 2002
Location: Ayrshire, Scotland
Distribution: Suse(home) RHEL (Work)
Posts: 263

Rep: Reputation: 30
Setting global variables from a crontab job

I've a simple test script:


case $SET_THIS in
one) export SET_THIS=two
two) export SET_THIS=three
three) export SET_THIS=one
*) export SET_THIS=one
echo $SET_THIS

It sets the $SET_THIS variable in the current shell if I run it will a '.' ie . ./setscript - but - how do I do this from running the command from a crontab job? Is it possibe? I would like the crontab job to know the previous value of the variable when the script starts...


Last edited by davee; 10-06-2003 at 05:03 AM.
Old 10-06-2003, 06:10 AM   #2
Registered: Oct 2003
Location: Gatwick, UK
Distribution: Mandrake 9.1, Mandrake 9.2, Redhat 9.0
Posts: 47

Rep: Reputation: 15
Hi Davee

This depends on how the variable is set, from an interactive shell session or a previous running of the crontab script.
1 Set by an interactive shell
I think that the way to do this is to create a logout script that edits your bash/ksh rc file to reflect the current value of the variable or if the variable needs to be the same each time you log in then create a separate file that contains the value and then place '. var_file' at the start of the crontab script ie
.bash_logout contains
echo "export SET_THIS=$SET_THIS" > ~/.cron_set

.bashrc contains
. ~/.cron_set - to set SET_THIS on each shell invocation
crontab script contains
. ~/.cron_set - To only set SET_THIS when run from crontab

2 Set by previous crontab script
Simply add .
~/.cron_set - to the start of the crontab script
echo "export SET_THIS=$SET_THIS" > ~/.cron_set - to the end of the script.

Don't forget to give an initial value in ./.cron_set
Old 10-06-2003, 07:05 AM   #3
Registered: Oct 2002
Location: Ayrshire, Scotland
Distribution: Suse(home) RHEL (Work)
Posts: 263

Original Poster
Rep: Reputation: 30
Thanks for that! I'll give it a try and see what happens. It's one of these things that doesn't seem to be covered in any of my linux books.

Cheers, Dave


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