File: coreutils.info, Node: who invocation, Prev: users invocation, Up: User information 20.6 `who': Print who is currently logged in ============================================ `who' prints information about users who are currently logged on. Synopsis: `who' [OPTION] [FILE] [am i] If given no non-option arguments, `who' prints the following information for each user currently logged on: login name, terminal line, login time, and remote hostname or X display. If given one non-option argument, `who' uses that instead of a default system-maintained file (often `/var/run/utmp' or `/var/run/utmp') as the name of the file containing the record of users logged on. `/var/log/wtmp' is commonly given as an argument to `who' to look at who has previously logged on. If given two non-option arguments, `who' prints only the entry for the user running it (determined from its standard input), preceded by the hostname. Traditionally, the two arguments given are `am i', as in `who am i'. Time stamps are listed according to the time zone rules specified by the `TZ' environment variable, or by the system default rules if `TZ' is not set. *Note Specifying the Time Zone with `TZ': (libc)TZ Variable. The program accepts the following options. Also see *note Common options::. `-a' `--all' Same as `-b -d --login -p -r -t -T -u'. `-b' `--boot' Print the date and time of last system boot. `-d' `--dead' Print information corresponding to dead processes. `-H' `--heading' Print a line of column headings. `-l' `--login' List only the entries that correspond to processes via which the system is waiting for a user to login. The user name is always `LOGIN'. `--lookup' Attempt to canonicalize hostnames found in utmp through a DNS lookup. This is not the default because it can cause significant delays on systems with automatic dial-up internet access. `-m' Same as `who am i'. `-p' `--process' List active processes spawned by init. `-q' `--count' Print only the login names and the number of users logged on. Overrides all other options. `-r' `--runlevel' Print the current (and maybe previous) run-level of the init process. `-s' Ignored; for compatibility with other versions of `who'. `-t' `--time' Print last system clock change. `-u' After the login time, print the number of hours and minutes that the user has been idle. `.' means the user was active in the last minute. `old' means the user has been idle for more than 24 hours. `-w' `-T' `--mesg' `--message' `--writable' After each login name print a character indicating the user's message status: `+' allowing `write' messages `-' disallowing `write' messages `?' cannot find terminal device An exit status of zero indicates success, and a nonzero value indicates failure.