USERMOD(8)                                                          USERMOD(8)


       usermod - Modify a user account


       usermod [-c comment] [-d home_dir [-m ]] [-e expire_date]
               [-f inactive_days] [-g initial_group]
               [-G group1 [ ,group2,... , [groupN] [-a] ]] [-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:

       -c comment
              The new value of the user’s password file comment field. It is
              normally modified using the chfn(1)utility.

       -d 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 expire_date
              The date on which the user account will be disabled. The date is
              specified in the format YYYY-MM-DD .

       -f inactive_days
              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 initial_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 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 -a option, which appends user to the current supplementary
              group list.

       -l login_name
              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.

       -L     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.

       -o     When used with the -u option, this option allows to change the
              user ID to a non-unique value.

       -p passwd
              The encrypted password, as returned by crypt(3).

       -s 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 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.

       -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 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.


              user account information

              secure user account information

              group account information


       chfn(1), chsh(1), passwd(1), crypt(3), gpasswd(8), groupadd(8),
       groupdel(8), groupmod(8), useradd(8), userdel(8).


       Julianne Frances Haugh (

                                  08/09/2005                        USERMOD(8)

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