Download/usr/bin/passwd offers a "safe way" for root to edit /etc/passwd (or shadow). If setuid it allows regular users to change passwd without asking root to do changes for them.
gnupasswd - gnu change user password
gnugpasswd - gnu change group password
gnupasswd(1) has a goal to work with older login.c/linux and some newer too, also "getpwent" (any glibc). or help convert.
gnupassd does pass only: leaves all else alone (compat). small, simpler for single admin / small linux bases.
For example: it can make plain /etc/passwd plain text password file (still) or use shadow - (login.c may do both).
A goal is to be old linux and no "depends problems" (ie, some required pam selinux audit kerb (+nis remove hacks) "to work as intended". These can contact remote computers during login if misconfigured and are complicated to configure (so that one knows what is allowed or not completely).
gnupasswd has none of these (gnu has NIS, off by default)
Features
- small simple to install, easy to read / hack
- careful coding - checks for errors always
- uses signals to prevent early quit
- uses glibc (set/end)pwent and file locking
- checks file permissions
- has internal pwd.h line parser if opted to use
- does not phone home, has no networking code
- supports SHADOW or not, crypt or not
- (see login.c that is altered to take old/new /etc/passwd)
- follows MAC (Mandatory Access Control)
- a few output options to help root convert or test
- it's old passwd(1) but new, but not too new
- it's fresh start code, not re-hacked code
- code uses long names, no mystery variables