NEWGRP(1)                                                            NEWGRP(1)


NAME
     newgrp - log in to a new group

SYNOPSIS
     newgrp [-] [ group ]

DESCRIPTION
     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.

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


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

BUGS
     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.


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