newgrp - Change to a new group

Format

newgrp [-l] [group]

newgrp [-] [group]

tcsh shell: newgrp [-] group

Description

Use newgrp to change to a new group. You stay logged in and your working directory does not change, but access permissions are calculated according to your new real and effective group IDs. If an error occurs, your session might be ended, and you must log in again.

After the group IDs are changed, a new shell is initialized within the existing process, effectively overlaying the current shell from which newgrp was invoked. The new shell is determined from the initial program value of the OMVS segment of your user profile.

newgrp does not change the value of exported shell variables, and all others are either set to their default or are unset.

If you did not specify any arguments on the command line, newgrp changes to the default group specified for your user ID in the system user database. It also sets the list of supplementary groups to that set in the systems group database.

If you specify a group, newgrp changes your real and effective group ID to that group. You are permitted to change to that group only if your user ID is a member of that group, as specified in the system group database.

group can be a group name from the security facility group database, or it can be a numeric group ID. If a numeric group exists as a group name in the group database, the group ID number that is associated with that group is used.

On systems where the supplementary group list also contains the new effective group ID or where the previous effective group ID was actually in the supplementary group list:
  • If the supplementary group list also contains the new effective group ID, newgrp changes the effective group ID.
  • If the supplementary group list does not contain the new effective group ID, newgrp adds it to the list (if there is room).
On systems where the supplementary group list does not normally contain the effective group ID or where the old effective group ID was not in the supplementary group list:
  • If the supplementary group list contains the new effective group ID, newgrp removes it from the list.
  • If the supplementary group list does not contain the old effective group ID, newgrp adds it to the list (if there is room).

newgrp in the tcsh shell, as in the z/OS shell, allows you to change to a new group.

Options

-l
Starts the new shell session as a login session. This implies that it can run any shell profile code.
-
Is the obsolete version of -l.

Localization

newgrp uses the following localization environment variables:
  • LANG
  • LC_ALL
  • LC_CTYPE
  • LC_MESSAGES
  • NLSPATH

Usage notes

  1. The RACF® profile FILE.GROUPOWNER.SETGID in the UNIXPRIV class sets the group of a new file from the process creating the file instead of from the Directory group information.
  2. newgrp allows you to change your default group in case RACF list of group checking is not enabled.
  3. newgrp is not supported from an address space running multiple processes because it would cause all processes in the address space to have their security environment changed unexpectedly. If you are using the OMVS interface, you must be using the NOSHAREAS parameter before you issue the newgrp command. Also, if you are running in an environment with the _BPX_SHAREAS environment variable set to YES, you must unset it and start a new shell before issuing newgrp. For example: 
    unset _BPX_SHAREAS; sh

Exit values

If newgrp succeeds, its exit status is that of the shell. Otherwise, the exit status is:
>0
Failure because newgrp could not obtain the proper user or group information or because it could not run the shell, and it ends the current shell.

Portability

POSIX.2 User Portability Extension, UNIX systems.

Related information

export, fc, sh, tcsh