what is the difference between /sbin/passwd and /usr/bin/passwd

[Hanry Zhou]

As far as I can see, they are doing the same thing: change the password, but have difference size.

Can anybody please let me know?

[A. Clay Stephenson]

This is a truism for everything is /sbin. It is statically linked code. The stuff is /usr/bin is (almost always) dynamically linked. Some utilities need to be able to be executed before any other filesystems are mounted. Most shared libraries reside in /usr/lib -- which is not mounted at boot.

This is the same reason to never replace root shell (/sbin/sh) with the seemingly equivalent /usr/bin/sh.

The dynamically linked versions are more memory efficient but require that other filesystems be mounted.

[Floyd Curtis]

/sbin commands are stand alone commands that are fully linked - having no shared library components allowing them to function in single user when pieces of the filesystem are not mounted.

fwc

[Sundar_7]

I cannot resist replying to this post..:-)

/usr/bin/passwd is dynamically linked and depends on shared executables to be present for successful execution. /sbin/passwd doesnt depend on shared libaries.

use file,ldd and chatr commands against these two files. you will under the difference.

[Bill Hassell]

As mentioned, the programs in /sbin are complete (all needed libraries are loaded into the executable). Dynamic excutables use shared libraries to reduce their size. During bootup, a command like mount is needed to mount the filesystems, but if this program needed shared libraries (which are stored in /usr) it could not run because /usr isn't mounted yet. The other major use of /sbin is in single user mode. /usr is not mounted in single user mode so there must be programs that run without /usr mounted.

[vasundhara]

The functionality of /sbin commands and /usr/bin commands are same. But, /sbin commands are very much helpful when silly things like "rm dld.sl" "rm /usr/bin/ls" "rm ?usr/sbin/mv" etc... are done. These commands only can save us to recover the system to original state.

Regards
VJ

[doug hosking]

VJ, it is USUALLY true that the two versions are the same or nearly so when comparing the /sbin and other versions. But passwd is special. /sbin/passwd is a 'bare bones' version of the /usr/bin/passwd command. The /sbin/passwd command is intended only for changing root's password in single user mode. For anything else you should be using /usr/bin/passwd.

The reason for this is that passwd and other commands depend heavily on PAM (Pluggable Authentication Modules). That is implemented by a series of libraries under /usr/lib. In single-user mode, /usr is often not mounted, so those libraries wouldn't be available in that case.

To emphasize the limited role of /sbin/passwd on newer HP-UX systems, the default permissions of /sbin/passwd have been changed to only allow superusers to execute it.