USERMOD linux command manual

USERMOD(8)                                                         USERMOD(8)

       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:

       -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 group,[...]
              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

       -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 direc-
              tory name should probably be changed to reflect the  new  login

       -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 99 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  direc-
              tory  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, effectively 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 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.

       /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), userdel(8)

       Julianne Frances Haugh (