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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 supplementary group(s). Use only with the -G
-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.
-f, --inactive INACTIVE
The number of days after a password expires until the account is
A value of 0 disables the account as soon as the password has
expired, and a value of -1 disables the feature.
-g, --gid GROUP
The group name or number of the user?s new initial login group. The
group must exist.
-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.
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. If the current home directory does not exist the new home
directory will not be created.
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
-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. Values between 0 and 999 are typically
reserved for system accounts.
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
The ownership of files outside of the user?s home directory must be
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).
-Z, --selinux-user SEUSER
The SELinux user for the user?s login. The default is to leave this
field the blank, which causes the system to select the default
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.
If MAIL_CHECK_ENAB is set to yes, they are also used to define the MAIL
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.
Secure 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).