irix - newgrp (1)

     newgrp - log in to	a new group

     newgrp [-]	[ group	]

     newgrp changes a user's group identification.  The	user remains logged in
     and the current directory is unchanged, but calculations of access
     permissions to files are performed	with respect to	the new	real and
     effective group IDs.  The user is always given a new shell, replacing the
     current shell, by newgrp, regardless of whether it	terminated
     successfully or due to an error condition (i.e., unknown group).

     Exported variables	retain their values after invoking newgrp; however,
     all unexported variables are either reset to their	default	value or set
     to	null.  System variables	(such as PS1, PS2, PATH, MAIL, and HOME),
     unless exported by	the system or explicitly exported by the user, are
     reset to default values.  For example, a user has a primary prompt	string
     (PS1) other than $	(default) and has not exported PS1.  After an
     invocation	of newgrp , successful or not, their PS1 will now be set to
     the default prompt	string $.  Note	that the shell command export (see
     sh(1)) is the method to export variables so that they retain their
     assigned value when invoking new shells.

     With no arguments,	newgrp changes the group identification	back to	the
     group specified in	the user's password file entry.	 This is a way to exit
     the effect	of an earlier newgrp command.

     If	the first argument to newgrp is	a -, the environment is	changed	to
     what would	be expected if the user	actually logged	in again as a member
     of	the new	group.

     A password	is not demanded	if any of the following	are true:

	  the caller is	superuser,

	  the caller's group id	(from /etc/passwd) matches the group's id, or

	  the caller is	a member of the	group (i.e. listed in the fourth field
	  of the group entry in	/etc/group).

     If	none of	the above conditions are met and the group has a password, the
     user is asked for it.  If the group does not have a password, the
     requested group-change is denied.

     /etc/group		 system's group	file
     /etc/passwd	 system's password file

     login(1), multgrps(1), id(1), groups(1), group(4),	passwd(4), environ(5)

     There is no convenient way	to enter a password into /etc/group.  Use of
     group passwords is	not encouraged,	because, by their very nature, they
     encourage poor security practices.	 Group passwords may disappear in the
     future.