usermod - Modify a user account
usermod [-c comment] [-d home_dir [-m]]
[-e expire_date] [-f inactive_time]
[-g initial_group] [-G group [,...]]
[-l login_name] [-p passwd]
[-s shell] [-u uid [-o]] [-L|-U] login
The usermod command modifies the system account files to reflect the changes that are
specified on the command line. The options which apply to the usermod command are:
The new value of the user's password file comment field. It is normally modified
using the chfn(1) utility.
The user's new login directory. If the -m option is given the contents of the cur-
rent home directory will be moved to the new home directory, which is created if it
does not already exist.
The date on which the user account will be disabled. The date is specified in the
The number of days after a password expires until the account is permanently dis-
abled. A value of 0 disables the account as soon as the password has expired, and
a value of -1 disables the feature. The default value is -1.
The group name or number of the user's new initial login group. The group name
must exist. A group number must refer to an already existing group. The default
group number is 1.
A list of supplementary groups which the user is also a member of. Each group is
separated from the next by a comma, with no intervening whitespace. The groups are
subject to the same restrictions as the group given with the -g option. If the
user is currently a member of a group which is not listed, the user will be removed
from the group
The name of the user will be changed from login to login_name. Nothing else is
changed. In particular, the user's home directory name should probably be changed
to reflect the new login name.
The encrypted password, as returned by crypt(3).
The name of the user's new login shell. Setting this field to blank causes the
system to select the default login shell.
-u uid The numerical value of the user's ID. This value must be unique, unless the -o
option is used. The value must be non-negative. Values between 0 and 99 are typi-
cally reserved for system accounts. Any files which the user owns and which are
located in the directory tree rooted at the user's home directory will have the
file user ID changed automatically. Files outside of the user's home directory
must be altered manually.
-L Lock a user's password. This puts a '!' in front of the encrypted password, effec-
tively disabling the password. You can't use this option with -p or -U.
-U Unlock a user's password. This removes the '!' in front of the encrypted password.
You can't use this option with -p or -L.
usermod will not allow you to change the name of a user who is logged in. You must make
certain that the named user is not executing any processes when this command is being exe-
cuted if the user's numerical user ID is being changed. You must change the owner of any
crontab files manually. You must change the owner of any at jobs manually. You must make
any changes involving NIS on the NIS server.
/etc/passwd - user account information
/etc/shadow - secure user account information
/etc/group - group information
chfn(1), chsh(1), passwd(1), crypt(3), groupadd(8), groupdel(8), groupmod(8), useradd(8),
Julianne Frances Haugh (email@example.com)