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
The new value of the user's password file comment field. It is
normally modified using the chfn(1) utility.
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.
The date on which the user account will be disabled. The date
is specified in the format YYYY-MM-DD.
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.
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.
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
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
The encrypted password, as returned by crypt(3).
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 nonnegative.
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 directory
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), crypt(3), groupadd(8), groupdel(8), groupmod(8),
passwd(1), useradd(8), userdel(8)
Julianne Frances Haugh (email@example.com)
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