-c|-a

At least one of -c or -a must be used.

-a

Last IMAP, POP, or http web mail client access (log in or log out) of user(s). -s does not affect the output of -a.

-c

List IMAP or Messenger Express users currently connected. 

-s service

Can specify either imap or http as service to monitor. Only applies to -c option. POP is not available because POP users do not typically stay logged on.

-u uid

Specify a UID to monitor. If -u and -f are not listed, then all users are monitored. 

-f filename

File containing UIDs to monitor. Each UID must be on its own line. 

--v

Returns version of this tool. 

--h

Returns usage information.