On CentOS, I need to grant a user root privilege, which was created before.


The usermod command modifies the system account files2 to reflect the changes that are specified on the command line.

Useful Options

-a, --append

Add the user to the supplementary group(s). Use only with the -G option.

-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.


usemod -a -G wheel <user name> would grant a specified user root priviledge.

  1. From man page.

  2. What files are system account files?