php exec tar call fails when run via cron, works via shell

Question

Can anyone explain why this line works when called from shell, but fails when called via crontab?

passthru("tar xvf $file $tarfile/application $tarfile/application_detail $tarfile/application_device_type $tarfile/genre_application");
}

The error I got emailed after cron was

tar: itunes20100907/application: Cannot open: No such file or directory itunes20100907/application_detail

Answer 1

As the error says, you must be in the wrong directory. You should use the canonical path.

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Note: When safe mode is enabled, you can only execute files within the safe_mode_exec_dir. For practical reasons, it is currently not allowed to have .. components in the path to the executable.