Run system command in perl cgi

polki · #1 (**permalink**) 03-18-2009

Hi guys,
got a problem with a perl cgi script over here. I need it to run a system command to get the status of a process. Unfortunately the process is owned by a specific user and only this user can get its status. So i tried running the command from the perl cgi with "su", but then i get the following logfile entry:

Quote:

su: must be run from a terminal

Anybody knows how to solve this problem? Another command? Another setting somewhere?

fpmurphy · #2 (**permalink**) 03-18-2009

Try using sudo if it is available on your system.

polki · #3 (**permalink**) 03-18-2009

Gave that a shot too, but the manpage of sudo says the following:

Quote:

If the invoking user is root or if the target user is the same as the invoking user, no password is required. Otherwise, sudo requires that users authenticate themselves with a password by default

So perl just grabs the output of sudo:

Quote:

[sudo] password for www-data:

Unfortunately www-data has no password, since it is not intended to be used as a system account. And apart from that, i don't even know how to submit this password to sudo...

pludi · #4 (**permalink**) 03-18-2009

Check the sudoers manpage for the NOPASSWD tag

polki · #5 (**permalink**) 03-18-2009

Thanks for the hint. Sounded like the right way, tried it by adding

Quote:

www-data ALL=NOPASSWD: ALL

to /etc/sudoers. Still the same log entry...

polki · #6 (**permalink**) 03-18-2009

Ok, seems like now the problem shifted a bit. After trying sudo from within perl, the auth-logfile showed this line:

Quote:

Mar 18 21:41:58 Debian sudo: pam_unix(sudo:auth): authentication failure; logname= uid=0 euid=0 tty= ruser= rhost= user=www-data

So from root i su'ed to ww-data and tried entering the command directly from within the command line. Result is this in auth.log:

Quote:

Mar 18 21:43:01 Debian sudo: pam_unix(sudo:auth): conversation failed
Mar 18 21:43:01 Debian sudo: pam_unix(sudo:auth): auth could not identify password for [www-data]
Mar 18 21:43:01 Debian sudo: www-data : pam_authenticate: Kommunikationsfehler ; TTY=pts/0 ; PWD=/var/log ; USER=<my desired user> ; COMMAND=<my desired command>

"Kommunikationsfehler" would mean something like communication failure or conversation failure in english.

Now I don't know how to continue at all. I just don't know Linux quite this well. Anybody got me ideas?

rikxik · #7 (**permalink**) 03-19-2009

Can you interactively connect as www-data?
If yes, from the www-data login what prompt you get when you do "sudo su -"?

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