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.

   -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.

   -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 list.

   -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
       or mail spool should probably be renamed manually to reflect the
       new login name.

   -L, --lock
       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.

       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.

       The password will be written in the local /etc/passwd or
       /etc/shadow file. This might differ from the password database
       configured in your PAM configuration.

       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.

       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.

       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).

   -v, --add-sub-uids FIRST-LAST
       Add a range of subordinate uids to the user's account.

       This option may be specified multiple times to add multiple ranges
       to a users account.

       No checks will be performed with regard to SUB_UID_MIN,
       SUB_UID_MAX, or SUB_UID_COUNT from /etc/login.defs.

   -V, --del-sub-uids FIRST-LAST
       Remove a range of subordinate uids from the user's account.

       This option may be specified multiple times to remove multiple
       ranges to a users account. When both --del-sub-uids and
       --add-sub-uids are specified, the removal of all subordinate uid
       ranges happens before any subordinate uid range is added.

       No checks will be performed with regard to SUB_UID_MIN,
       SUB_UID_MAX, or SUB_UID_COUNT from /etc/login.defs.

   -w, --add-sub-gids FIRST-LAST
       Add a range of subordinate gids to the user's account.

       This option may be specified multiple times to add multiple ranges
       to a users account.

       No checks will be performed with regard to SUB_GID_MIN,
       SUB_GID_MAX, or SUB_GID_COUNT from /etc/login.defs.

   -W, --del-sub-gids FIRST-LAST
       Remove a range of subordinate gids from the user's account.

       This option may be specified multiple times to remove multiple
       ranges to a users account. When both --del-sub-gids and
       --add-sub-gids are specified, the removal of all subordinate gid
       ranges happens before any subordinate gid range is added.

       No checks will be performed with regard to SUB_GID_MIN,
       SUB_GID_MAX, or SUB_GID_COUNT from /etc/login.defs.

   -Z, --selinux-user SEUSER
       The new SELinux user for the user's login.

       A blank SEUSER will remove the SELinux user mapping for user LOGIN
       (if any).

CAVEATS

   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, the user's name, or the user's home directory is being
   changed.  usermod checks this on Linux, but only check if the user is
   logged in according to utmp on other architectures.

   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.

   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.

   SUB_GID_MIN (number), SUB_GID_MAX (number), SUB_GID_COUNT (number)
       If /etc/subuid exists, the commands useradd and newusers (unless
       the user already have subordinate group IDs) allocate SUB_GID_COUNT
       unused group IDs from the range SUB_GID_MIN to SUB_GID_MAX for each
       new user.

       The default values for SUB_GID_MIN, SUB_GID_MAX, SUB_GID_COUNT are
       respectively 100000, 600100000 and 10000.

   SUB_UID_MIN (number), SUB_UID_MAX (number), SUB_UID_COUNT (number)
       If /etc/subuid exists, the commands useradd and newusers (unless
       the user already have subordinate user IDs) allocate SUB_UID_COUNT
       unused user IDs from the range SUB_UID_MIN to SUB_UID_MAX for each
       new user.

       The default values for SUB_UID_MIN, SUB_UID_MAX, SUB_UID_COUNT are
       respectively 100000, 600100000 and 10000.

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.

   /etc/subgid
       Per user subordinate group IDs.

   /etc/subuid
       Per user subordinate user IDs.

SEE ALSO

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





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