use this command to add comments to a user's account in your linux server.

for example, lets say we have a username: edwardgomez and we want to put edwardgomez's contact phone number. so we can use the comments -c option like this:

# usermod -c 213-555-1212 edwardgomez

some other option of the usermod command are:

-g change the primary group
-G set the supplementary group
-e = set the account expire date
-s = change the login shell