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
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