usermod

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.

root@linuxreference:/root#id thomas

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