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USERMOD(8)                                    System Management Commands                                   USERMOD(8)



NAME
       usermod - modify a user account

SYNOPSIS
       usermod [options] LOGIN

DESCRIPTION
       The usermod command modifies the system account files to reflect the changes that are specified on the command
       line.

OPTIONS
       The options which apply to the usermod command are:

       -a, --append
           Add the user to the supplementary group(s). Use only with the -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. If the current home directory does not exist the
           new home directory will not be created.

       -e, --expiredate EXPIRE_DATE
           The date on which the user account will be disabled. The date is specified in the format YYYY-MM-DD.

           An empty EXPIRE_DATE argument will disable the expiration of the account.

           This option requires a /etc/shadow file. A /etc/shadow entry will be created if there were none.

       -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.

           This option requires a /etc/shadow file. A /etc/shadow entry will be created if there were none.

       -g, --gid GROUP
           The group name or number of the user's new initial login group. The group must exist.

           Any file from the user's home directory owned by the previous primary group of the user will be owned by
           this new group.

           The group ownership of files outside of the user's home directory must be fixed manually.

           The change of the group ownership of files inside of the user's home directory is also not done if the
           home dir owner uid is different from the current or new user id. This is safety measure for special home
           directories such as /.

       -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
           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.

       -m, --move-home
           Move the content of the user's home directory to the new location. If the current home directory does not
           exist the new home directory will not be created.

           This option is only valid in combination with the -d (or --home) option.

           usermod will try to adapt the ownership of the files and to copy the modes, ACL and extended attributes,
           but manual changes might be needed afterwards.

       -o, --non-unique
           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).

           Note: This option is not recommended because the password (or encrypted password) will be visible by users
           listing the processes.

           You should make sure the password respects the system's password policy.

       -R, --root CHROOT_DIR
           Apply changes in the CHROOT_DIR directory and use the configuration files from the CHROOT_DIR directory.

       -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 new numerical value of the user's ID.

           This value must be unique, unless the -o option is used. The value must be non-negative.

           The user's mailbox, and any files which the user owns and which are located in the user's home directory
           will have the file user ID changed automatically.

           The ownership of files outside of the user's home directory must be fixed manually.

           The change of the user ownership of files inside of the user's home directory is also not done if the home
           dir owner uid is different from the current or new user id. This is safety measure for special home
           directories such as /.

           No checks will be performed with regard to the UID_MIN, UID_MAX, SYS_UID_MIN, or SYS_UID_MAX from
           /etc/login.defs.

       -U, --unlock
           Unlock a user's password. This removes the '!' in front of the encrypted password. You can't use this
           option with -p or -L.


       You must change the owner of any crontab files or at jobs manually.

       You must make any changes involving NIS on the NIS server.

CONFIGURATION
       The following configuration variables in /etc/login.defs change the behavior of this tool:

       MAIL_DIR (string)
           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.

       MAIL_FILE (string)
           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.

       If MAIL_CHECK_ENAB is set to yes, they are also used to define the MAIL environment variable.

       MAX_MEMBERS_PER_GROUP (number)
           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.

FILES
       /etc/group
           Group account information.

       /etc/gshadow
           Secure group account information.

       /etc/login.defs
           Shadow password suite configuration.

       /etc/passwd
           User account information.

       /etc/shadow
           Secure user account information.

SEE ALSO
       chfn(1), chsh(1), passwd(1), crypt(3), gpasswd(8), groupadd(8), groupdel(8), groupmod(8), login.defs(5),
       useradd(8), userdel(8).