PHP can't execute shell command !

rome · 11-15-2005, 06:45 AM

Hello world,
I've installed my PHP application on a remote server with Debian Linux and
plesk 7.5 reloaded, my assigned php-user is www-data (instead of the default "apache") and every command that I call with "exec" or "shell_exec" or "system" return the error code 127.

if I enter the shell as root I can do anything but
whenever I type "su - www-data" the return is "no shell"

So I don't know wether this is caused by some php configuration directives or OS user permissions settings.

who knows debian and plesk ? who knows this problem ?
my server administrators don't know how to resolve this issue.

help me !

cs-cam · 11-15-2005, 07:17 AM

The user hasn't been setup with a shell by the looks of it. Post the output of this command:

Code:

/etc/passwd | grep www-data | sed -e "s/.*://g"

You'll need to run it as root but that uses sed to chop out everything we don't need which may include an encrypted password. This will only show us the login shell and if my guess is right then you just need to change the end of this line to read /bin/bash

rome · 11-15-2005, 07:49 AM

Quote:

Originally posted by cs-cam
The user hasn't been setup with a shell by the looks of it. Post the output of this command:

Code:

/etc/passwd | grep www-data | sed -e "s/.*://g"

You'll need to run it as root but that uses sed to chop out everything we don't need which may include an encrypted password. This will only show us the login shell and if my guess is right then you just need to change the end of this line to read /bin/bash

All right, I solved it.

The issue was a little bit more complicated than that.
/bin/bash had weird permissions: (was not executable but by root user)
Having changed them with

Code:

chmod o+rx /bin/bash

changes the error code returned by system("id", $ret_code) invoked in php, from 127 to 126.
That should, from "path not found", to "command was not executable".

Then I discovered that the whole bin/ and /usr/bin/ directories had weird permissions (group ownler couldn't execute nor read).
Giving read and execute permissions to all the commands solved the issue.
I guess it had to do with the plesk installation.

By the way, running

Code:

cat /etc/passwd | grep www-data | sed -e "s/.*://g"

returns

Code:

/bin/false

since usually there's no need to assign a shell to apache users.

And letting the user have /bin/false as a shell does not stop php from running shell commands through exec.

Thanks anyway for your help.

Any idea?

unSpawn · 11-15-2005, 12:46 PM

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