NAME

usermod − modify a user’s login information on the system

SYNOPSIS

usermod [−u uid [−o]] [−g group] [−G group[,group...] [−d dir [−m]] [−s shell]
[−c comment] [−l new_logname] [−f inactive] [−e expire] login

DESCRIPTION

The usermod command modifies a user’s login definition on the system.  It changes the definition of the specified login and makes the appropriate login-related system file and file system changes. 

The system file entries created with this command have a limit of 512 characters per line.  Specifying long arguments to several options may exceed this limit. 

The following options are available:

−u uid
New UID for the user. It must be a non-negative decimal integer below MAXUID as defined in param.h. 

−o This option allows the specified UID to be duplicated (non-unique). 

−g group
An existing group’s integer ID or character-string name. It redefines the user’s primary group membership.

−G group
An existing group’s integer “ID” “,” or character string name. It redefines the user’s supplementary group membership. Duplicates between group with the −g and −G options are ignored.  No more than NGROUPS_UMAX groups may be specified as defined in param.h. 

−d dir
The new home directory of the user. It defaults to base_dir/login, where base_dir is the base directory for new login home directories, and login is the new login. 

−m Move the user’s home directory to the new directory specified with the −d option.  If the directory already exists, it must have permissions read/write/execute by group, where group is the user’s primary group. 

−s shell
Full pathname of the program that is used as the user’s shell on login. The value of shell must be a valid executable file. 

−c comment
Any text string. It is generally a short description of the login, and is currently used as the field for the user’s full name. This information is stored in the user’s /etc/passwd entry. 

−l new_logname
A string of printable characters that specifies the new login name for the user. It may not contain a colon (:) or a newline (\n). 

−e expire
The date on which a login can no longer be used; after this date, no user will be able to access this login. (This option is useful for creating temporary logins.) You may type the value of the argument expire (which is a date) in any format you like (except a Julian date).  For example, you may enter 10/6/90 or October 6, 1990.  A value of “ ” defeats the status of the expired date. 

−f inactive
The maximum number of days allowed between uses of a login ID before that login ID is declared valid.  Normal values are positive integers.  A value of −1 defeats the status. 

login A string of printable characters that specifies the existing login name of the user.  It must exist and may not contain a colon (:), or a newline (\n). 

FILES

/etc/passwd, /etc/shadow, /etc/group

SEE ALSO

groupadd(1M), groupdel(1M), groupmod(1M), logins(1M), passwd(1), passwd(1M), useradd(1M), userdel(1M), users(1)

DIAGNOSTICS

The usermod command exits with one of the following values:

0 The command was executed successfully. 

2 The command syntax was invalid.  A usage message for the usermod command is displayed. 

3 An invalid argument was provided to an option. 

4 The uid given with the −u option is already in use. 

6 The login to be modified does not exist or group does not exist. 

8 The login to be modified is in use. 

9 The new_logname is already in use. 

10 Cannot update the /etc/group file.  Other update requests will be implemented. 

11 Insufficient space to move the home directory (−m option).  Other update requests will be implemented. 

12 Unable to complete the move of the home directory to the new home directory.