The pwck command checks the integrity of /etc/passwd and /etc/shadow, and grpck checks /etc/group and /etc/gshadow. They look for correct format, valid data, valid names, and valid GIDs (see the man pages for a complete list). When you run these with no options, they report both w...
The options which apply to the pwck command are: TagDescription -q Report errors only. The warnings which do not require any action from the user won’t be displayed. -r Execute the pwck command in read-only mode. -s Sort entries in /etc/passwd and /etc/shadow by UID. ...