usermod – Enables a super user or root user to modify a users account.
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 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 formatYYYY-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 directory name should probably be changed to reflect the new login name.
-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 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.
Add new group called hr to thomas, use usermod command with -G option.
uid=1001(thomas) gid=100(users) groups=100(users)
root@linuxreference:/root#usermod -G users,hr thomas
uid=1001(thomas) gid=100(users) groups=100(users),103(hr)
Set Expired date for thomas user account, user usermod command with -e option
root@linuxreference:/root#usermod -e 2011-08-26 thomas
Set brief command for thomas user account, use usermod command with -c option
root@linuxreference:/root#usermod -c HRManager thomas
Change user account login name, with condition user not login into the system. User usermod command with -l option
root@linuxreference:/root#usermod -l mansion thomas