Linux是多用户操作系统，支持多用户同时在线，支持对登陆用户的管理：查看与剔除等。

一、查看在线用户命令

命令： w

二、查看登录记录命令 

命令 last

三、剔除在线用户命令

命令：sudo pkill -kill -t usr

四、pkill用法

Usage:pkill [options] <pattern>
Options:
-<sig>, --signal <sig>    signal to send (either number or name)
-e, --echo                display what is killed
-c, --count               count of matching processes
-f, --full                use full process name to match
-g, --pgroup <id,...>     match listed process group IDs
-G, --group <gid,...>     match real group IDs
-n, --newest              select most recently started
-o, --oldest              select least recently started
-P, --parent <ppid,...>   match only child processes of the given parent
-s, --session <sid,...>   match session IDs
-t, --terminal <tty,...>  match by controlling terminal
-u, --euid <id,...>       match by effective IDs
-U, --uid <id,...>        match by real IDs
-x, --exact               match exactly with the command name
-F, --pidfile <file>      read PIDs from file
-L, --logpidfile          fail if PID file is not locked
--ns <pid>                match the processes that belong to the samenamespace as <pid>
--nslist <ns,...>         list which namespaces will be considered forthe --ns option.Available namespaces: ipc, mnt, net, pid, user, uts-h, --help     display this help and exit-V, --version  output version information and exit