welp this stinks. i'm a redhat8 user and i screwed up my password file. if u guys dont know what im talking about, it is /etc/passwd

and somehow i messed it up. its a read-only file, and on the first line where it should say .../bin/bash, it only says /bin.

that is a problem because there is no shell defined for the root user. i can't login as root!
there are other passwd files though, such as the passwd.OLD located in the same directory. since these files cannot be altered, (except by root) i need another way to restore the old passwd file or change the current one by hand. i have never run in to this problem in my entire 4 year career with redhat, so i believe this could be a rare problem. please help as i really need to login and install some packages!

Try booting your system either by single mode or rescue mode. You should be able to alter the passwd file since those mode doesn't require any user login.

Login as yourself and do

su - --shell=/bin/bash

that does not work! i get the error:

cannot login: /bin
permision denied

Use the first RH8 install disk and type "linux rescue" at the prompt. It will go through a startup that might make you think it is trying to install, don't worry, just answer the questions it asks (mouse keyboard language etc) then it will search for (and hopefully find) your system then mount it at /mnt/sysimage. chroot to /mnt/sysimage, cd to /etc then do a mv passwd.OLD passwd and reboot.

Sorry, probably better to cp passwd.OLD passwd

Else you can try and fix passwd manually...

What do you mean by "that" ?

Do you mean you cant login as yourself ?
OR
Do you mean the su command errors out?

If all you changed was root's login shell, then there is no reason that EITHER of those shouldn't work. If that is the case, there's something else going on and you'll have to use your rescue cd and follow bulliver's instructions.