Users and groups

Listing group information | Changing groups | Changing user and group for files/directories

HPSS users get access to certain directories and files based on their group membership and how permissions are established. One directory might be accessible to only one individual, for example, while in another directory all users who are members of a specified group might be able to read, write, and execute files.

Your username and a corresponding User ID (UID) number are associated with your primary group. The primary group is identified by a Group ID (GID) number and a group name – 1000 (ncar), for example. You also may be a member of a number of secondary groups. Your HPSS username and UID are the same ones that you use on the computing systems that CISL manages.

When you establish an HSI session, you are assigned initially to your primary group or your current effective group. Within the session, you can change to another group with which you are associated in order to work with a different set of files. (To request a persistent change in your primary or secondary groups, contact CISL.)

Following are instructions for identifying and working with your groups.

Listing group information

To list your current effective GID number and group name in an HSI session, enter newgrp.

[HSI]/home/username-> newgrp
Current group is: 1000(ncar)

To list your primary and secondary groups while you are in a session, just enter groups.

[HSI]/home/username-> groups
N:HPSS Group List:
1000: ncar      1234: abc

Enter id to list your current user and group information in a session.

[HSI]/home/username-> id
uid=12345(username) gid=1000(ncar) 999(our_group) 1100(other_group)

Changing groups

To change your current effective group for an HSI session, either specify the group name when you start the session or make the change within the session.

Run the hsi command with the -g option to start a session.

hsi -g group_name

Within a session, use newgrp like this:

[HSI]/home/username-> newgrp group_name

The change will persist in that session until you enter another newgrp command.

Changing user and group for files/directories

Limitations on changing the associated user (owner) and group for files and directories in HPSS are the same as the limitations in UNIX and Linux:

  1. You cannot change ownership of a file. If file ownership must be changed, contact CISL.
  2. You can use the chgrp command to change the group for a file or directory as long as you are authorized for that group. The chgrp command also resets a file's project code to your default project code, so be especially careful with this if you have multiple projects to which you can charge. Check to be sure the correct project code is being charged and change it as needed.

Example: Change the group name for "myfile" to "other_group":

[HSI]/home/username-> chgrp other_group myfile

Example: Change the GID for "myfile" to "999":

[HSI]/home/username-> chgrp 999 myfile

To see the effects of changes, use ls -l to list the files or directories.