newgrp — change to a new primary group
newgrp [-l] [group] [command
[args...]
]
newgrp starts a new shell environment under a new primary group.
If the -l flag is given as first argument, the
user's environment will be reinitialized as though the user had logged
in, otherwise the current environment, including current working
directory, remains unchanged. For Linux compatibility, the flag
- is allowed as well.
newgrp changes the current primary group to the
named group, or to the default group listed in /etc/passwd if no group
name is given. The user's standard shell is started, called as login
shell if the -l or - flag has been
specified.
The group argument can be specified as group name from the group database or a non-negative numeric group ID.
If a group has been given as argument, a command and its arguments can be specified on the command line. Note that this usage is Cygwin-only and incompatible with POSIX and Linux.
The new primary group must be either the old primary group, or it must be part of the supplementary group list. Setting the primary group to an arbitrary group is not allowed in Windows.