illegal command error code 127 in php exec function

Try using the direct path of the application (/usr/bin/unrar of whatever), it sounds like php can't find the application.

If you have chrooted apache and php, you will also want to put /bin/sh into the chrooted environment. Otherwise, the exec() or passthru() will not function properly, and will produce error code 127, file not found.

Since this comes up as a top answer in google, I wanted to share my fix:

The simple fix I had was to disable safe_mode in the php.ini file

; Safe Mode
; http://www.php.net/manual/en/ini.sect.safe-mode.php#ini.safe-mode
safe_mode = Off

thanx all for your response!!

I tried this

//somedir is inside the directory where php file is
chdir("somedir");
exec("/home/username/bin/unrar e /home/path/to/dir/file.rar");

and now it returned no exit code ... oher commands are doing file .. i tried mkdir etc .. :s