newgrp:tldr:e3421

The command "newgrp ${group_name}" is used to change the primary group of the currently logged-in user to a new group specified by the ${group_name} variable.

In Unix-like systems, a user has a primary group associated with their account. This primary group is used as the default group ownership for files and directories created by that user. By running the "newgrp" command, the user can temporarily switch their primary group to the specified group.

Here's how the command works:

1. ${group_name} is a placeholder for the name of the group you want to switch to. It should be replaced with the actual group name without the "${}".
2. When the command is executed, it verifies if the user is a member of the group specified by ${group_name}.
3. If the user is a member of the group, it creates a new shell with the primary group set to ${group_name}.
4. The new shell inherits the environment of the current shell, but with the new primary group.
5. The user can now perform actions that require the group permissions and file access of ${group_name}.
6. To return to the original primary group, the user simply needs to exit the new shell.

Please note that the user needs to have the necessary permissions and be a member of the ${group_name} group in order to use the "newgrp" command.