Provided by: passwd_4.1.1-1ubuntu1_i386
usermod - modify a user account
usermod [options] 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:
Add the user to the supplemental group(s). Use only with -G option.
-c, --comment COMMENT
The new value of the user´s password file comment field. It is
normally modified using the chfn(1) utility.
-d, --home HOME_DIR
The user´s new login directory. If the -m option is given the
contents of the current home directory will be moved to the new
home directory, which is created if it does not already exist.
-e, --expiredate EXPIRE_DATE
The date on which the user account will be disabled. The date is
specified in the format YYYY-MM-DD.
-f, --inactive INACTIVE
The number of days after a password expires until the account is
permanently disabled. 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.
-g, --gid GROUP
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.
-G, --groups GROUP1[,GROUP2,...[,GROUPN]]]
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. This behaviour can be changed via the -a
option, which appends the user to the current supplementary group
-l, --login NEW_LOGIN
The name of the user will be changed from LOGIN to NEW_LOGIN.
Nothing else is changed. In particular, the user´s home directory
name should probably be changed manually to reflect the new login
Lock a user´s password. This puts a ´!´ in front of the encrypted
password, effectively disabling the password. You can´t use this
option with -p or -U.
Note: if you wish to lock the account (not only access with a
password), you should also set the EXPIRE_DATE to 1.
When used with the -u option, this option allows to change the user
ID to a non-unique value.
-p, --password PASSWORD
The encrypted password, as returned by crypt(3).
-s, --shell SHELL
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 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 999 are typically 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.
Unlock a user´s password. This removes the ´!´ in front of the
encrypted password. You can´t use this option with -p or -L.
Note: if you wish to unlock the account (not only access with a
password), you should also set the EXPIRE_DATE (for example to
99999, or to the EXPIRE value from /etc/default/useradd).
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 executed 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.
The following configuration variables in /etc/login.defs change the
behavior of this tool:
The mail spool directory. This is needed to manipulate the mailbox
when its corresponding user account is modified or deleted. If not
specified, a compile-time default is used.
Defines the location of the users mail spool files relatively to
their home directory.
The MAIL_DIR and MAIL_FILE variables are used by useradd, usermod, and
userdel to create, move, or delete the user´s mail spool.
Maximum members per group entry. When the maximum is reached, a new
group entry (line) is started in /etc/group (with the same name,
same password, and same GID).
The default value is 0, meaning that there are no limits in the
number of members in a group.
This feature (split group) permits to limit the length of lines in
the group file. This is useful to make sure that lines for NIS
groups are not larger than 1024 characters.
If you need to enforce such limit, you can use 25.
Note: split groups may not be supported by all tools (even in the
Shadow toolsuite. You should not use this variable unless you
really need it.
Group account information.
User account information.
Secure user account information.
chfn(1), chsh(1), passwd(1), crypt(3), gpasswd(8), groupadd(8),
groupdel(8), groupmod(8), login.defs(5), useradd(8), userdel(8).