change shell on login as root

[diego mec]

Hi,
I have a problem with the shell of user root, I changed the default shell directly in /etc/passwd file (big mistake), removing /sbin/sh and inserting /usr/local/bin/bash. But this shell, bash, is not properly installed, so now I cannot login or su - root.
Of course, I am not able also to modify back this file since I cannot login as root.
If I do su - root, I get an error when the system tries to load the bash shell and am disconnected.
The server is remote so I cannot access the console.
Is there any means to login as root but using sh shell and then fix the problem?

Thanks

[Torsten.]

Never, never change root's shell in /etc/passwd.

Now try this:

# su root -c /sbin/sh

[Rajeev Shukla]

You shouldn't really change the shell of root coz root's shell should only reside in /sbin and also libraries required should be /lib which means only /sbin/sh is accepted as shell of root.
One way you could try is ftp the /etc/passwd to someother server, edit the file and put the file back using ftp.
Coz any other methods will use shell from passwd file and wont let you login.

[Deepak Kr]

Yes, default shell for root user should never change to other like ksh or bash (in linux)...

This is HP recommendation also.

Doing ftp is good option as rajeev suggested..

[diego mec]

Hi,
I already tested su - root -c /sbin/sh but does not work coz shell is loaded before.
I have tried your suggestion but ftp also fails... I see in syslog file:
FTP LOGIN REFUSED (shell not in /etc/shells)

Would it be possible to fix at least connecting on the console? I suppose that shell is not loaded in single-user osr something like that and /etc/passwd might be changed, or not

Thanks

[Torsten.]

If you bring down the server and boot again, the system will complain about the shell, stop boot and end with a /sbin/sh prompt.

The only problem is to bring down the system - last effort will be a power cycle or hard reset.

[Robert-Jan Goossens]

Hi Diego,

Would it be possible to fix at least connecting on the console? I suppose that shell is not loaded in single-user osr something like that and /etc/passwd might be changed, or not

Yes, but you will have to reboot your server. You don't have to boot in to single user mode, this will be done automaticly.

Login
# mount -a
set your TERM
# vi /etc/passwd
and change the root shell back to /sbin/sh
:wq!
# shutdown -r -y now

Regards,
Robert-Jan

[Rasheed Tamton]

Hi,

You have not really tried what Torsten suggested!

su root -c /sbin/sh

You still used a hyphen in front of the root. Use it without the hyphen (dash). Just use
su root

Rgds.

[diego mec]

Hi,
in fact I did test all possibilities, including without the hyphen:
som@gpparlay[HP-UX]:/home/som# su root -c /sbin/sh
Password:
/usr/lib/hpux32/dld.so: Unable to find library 'libtermcap.so'.
Killed

[Heironimus]

If you have sudo you can use it to invoke a shell as root. sudo does not rely on the shell defined in /etc/passwd.

If you have an NFS mount you might be able to put a setuid shell on the server and run it on the client to get root access.