The who command displays a list of all logged in users/display info about current user The who utility displays a list of all users currently logged on, showing for each user the login name, tty name, the date and time of login, and hostname if not local.


Here are just some of the most useful options for this command:
  • -b: Display time of last system boot.
  • -d: Print dead processes.
  • -H: Write column headings above the regular output.
  • -m: Only print information about the current terminal.
  • -q: Quick mode: List only the names and the number of users currently logged on. When this option is used, all other options are ignored.
  • -s: List only the name, line and time fields. This is the default.
  • -T: Print a character after the user name indicating the state of the terminal line: "+" if the terminal is writable; "-" if it is not; and "?" if a bad line is encountered.
  • -u: Print the idle time for each user, and the associated process ID.
  • am I: Returns the invoker's real user name. You can also use whoami
  • file: By default, who gathers information from the file /var/run/utmpx. An alternative file may be specified.