Cronjob creates multiple processes for the same script. One using
/usr/bin/php /path/to/php/script
And other using
/bin/sh -c /usr/bin/php /path/to/php/script
These are 2 separate processes. Why does this happen? I am running Ubuntu 14.10 server.
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VarunS03
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Is one process the parent of the other? (hint: use 'ps fax' to see the relation between processes) – JvO May 17 '16 at 14:01
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yes, /bin/sh -c ... was the parent of the /usr/bin/php.... process. – VarunS03 May 19 '16 at 06:45
1 Answers
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In your case the
/bin/sh -c /usr/bin/php /path/to/php/script
Is likely the parent of:
/usr/bin/php /path/to/php/script
Cron will execute /bin/sh -c of the command you have in your crontab. /bin/sh will then spawn a child process of the actual command you want to run, in your case:
/usr/bin/php /path/to/php/script
H K
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Yes, correct, /bin/sh -c was the parent of /usr/bin/php.. process. The processes were executing script, making changes to the system, but were not killed. Not sure why and how. Anyways I have specified the SHELL=/bin/bash in my crontab, and it seems to execute only a single process. Thanks for your explanation. I believe crontab uses /bin/sh as the default shell. – VarunS03 May 19 '16 at 06:49