[Chicago-talk] Is it running from cron?

Andy_Bach at wiwb.uscourts.gov Andy_Bach at wiwb.uscourts.gov
Thu Feb 22 09:26:08 PST 2007


> >
> FROM_CRON=1
> 1 2 3 4 5 /some/command some args

Couple hints - best to make a script and run that instead of a command, as 
you can alter the script as needed. You can also set all the vars you 
want. Modern (Vixie-ish) crons set some env vars (see
man 5 crontab
  Several  environment  variables are set up automatically by the cron(8)
       daemon.  SHELL is set to /bin/sh, and LOGNAME and HOME are set from 
the
       /etc/passwd  line  of the crontabâs owner.  HOME and SHELL may be 
over-
       ridden by settings in the crontab; LOGNAME may not.

       (Another note: the LOGNAME variable is sometimes  called  USER  on 
BSD
       systems...  on these systems, USER will be set also.)

       In addition to LOGNAME, HOME, and SHELL, cron(8) will look at 
MAILTO if
       it has any reason to send mail as  a  result  of  running  commands 
 in
       ââthisââ  crontab.   If MAILTO is defined (and non-empty), mail is 
sent
       to the user so named.  If MAILTO is defined but empty  (MAILTO=""), 
 no
       mail will be sent. 
...
       Environment variables can be set in the crontab.  In BSD  or  ATT, 
the
       environment  handed  to  child  processes  is  basically  the  one 
from
       /etc/rc.

But note - expansions *don't* work, e.g.
PATH=$PATH:/usr/local/bin

won't give (/bin:/usr/bin is the standard cron-given path ... so FQ 
executable names is always worth it - even if it is /bin/grep)
PATH=/bin:/usr/bin:/usr/local/bin

but:
$PATH:/usr/local/bin

(just put:
PATH=$PATH:/usr/local/bin
6 11 * * * root /bin/echo $PATH

in /etc/cron.d/test - as long as the set time is more than a minute away 
from now). 

a

Andy Bach
Systems Mangler
Internet: andy_bach at wiwb.uscourts.gov
VOICE: (608) 261-5738  FAX 264-5932

"Procrastination is like putting lots and lots of commas in the sentence 
of your life."
Ze Frank 
http://lifehacker.com/software/procrastination/ze-frank-on-procrastination-235859.php


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