newgrp(1M)                                                       newgrp(1M)


   NAME
         newgrp - log in to a new group

   SYNOPSIS
         newgrp [-] [ group ]

   DESCRIPTION
         newgrp changes a user's real and effective group ID.  The user
         remains logged in and the current directory is unchanged. 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, the
         user's PS1 will now be set to the default prompt string $.  Note that
         the shell command export [see the sh(1) manual page] is the method to
         export variables so that they retain their assigned value when
         invoking new shells.

         With no arguments, newgrp changes the user's group IDs (real and
         effective) 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 demanded if the group has a password and the user is
         not listed in /etc/group as being a member of that group.

   FILES
         /etc/group
                   system's group file

         /etc/passwd
                   system's password file

   SEE ALSO
         login(1), sh(1) in the User's Reference Manual.
         group(4), passwd(4), environ(5) in the System Administrator's
         Reference Manual.
         see intro(2) ``Effective User ID and Effective Group ID" in
         Programmer's Reference Manual



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