Linux in a Nutshell, Fifth Edition

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Chapter 3: Linux Commands

This is the Title of the Book, eMatter Edition

Copyright © 2006 O’Reilly & Associates, Inc. All rights reserved.

-G groups

Supplementary groups given by name or number in a comma-

separated list with no whitespace. user will be removed from

any groups to which it currently belongs that are not included

in groups.

-l name

Login name. This cannot be changed while the user is logged

in.

-L Lock user’s password by putting a ! in front of it. This option

cannot be used with -p or -U.

-o Override. Accept a nonunique uid with the -u option.

-p pw

Encrypted password, as returned from crypt(3).

-s shell

Login shell.

-u uid

Numerical user ID. The value must be unique unless the -o

option is used. Any files owned by user in the user’s home

directory will have their user ID changed automatically. Files

outside of the home directory will not be changed. user should

not be executing any processes while this is changed.

-U Unlock the user’s password by removing the ! that -L put in

front of it. This option cannot be used with -p or -L.

users

users [file]

users option

Print a space-separated list of each login session on the host. Note

that this may include the same user multiple times. Consult file or,

by default, /var/log/utmp or /var/log/wtmp.

Options

--help

Print usage information and exit.

--version

Print version information and exit.

usleep

usleep [microseconds]

usleep [options]

Sleep some number ...