who 命令

常用示例

说明

who displays information about users currently logged into the system. It reads from /var/run/utmp (or another specified file) which tracks login sessions. The basic output shows username, terminal line, and login time. Additional options reveal idle time, process IDs, and message status (whether the user accepts write/talk messages). who am i shows information about the original login session. Unlike whoami (which shows the effective user), who am i displays the user who originally logged in, even after su to another account. The command can read historical login data from /var/log/wtmp to show past logins.

参数

-a, --all

Print all available information

-b, --boot

Time of last system boot

-d, --dead

Print dead processes

-H, --heading

Print column headers

-l, --login

Print system login processes

-q, --count

Only usernames and count of logged-in users

-r, --runlevel

Print current runlevel

-p, --process

Print active processes spawned by init

-s, --short

Print only name, line, and time (default)

-t, --time

Print last system clock change

-T, -w, --mesg

Add user's message status (+, -, ?)

-u, --users

List users logged in

--lookup

Attempt to canonicalize hostnames via DNS

am i

Print only current terminal's user info