大家应该都知道查询一个用户的数据，用id、finger

appledeMacBook-Pro:~ apple$ id
uid=501(apple) gid=20(staff) groups=20(staff),701(com.apple.sharepoint.group.1),12(everyone)

appledeMacBook-Pro:~ apple$ finger
Login    Name                 TTY  Idle  Login  Time   Office  Phone
apple    apple               *con   22d   1 30  20:07
apple    apple                s00    3d   1 30  20:07
apple    apple                s00    3d   2  1  10:01
apple    apple                s00         2  1  10:19
apple    apple                s00     1   2  3  10:00
apple    apple                s00    3d   2  4  12:18

那如果查询当前系统已登陆用户呢？用w和who查询

appledeMacBook-Pro:~ apple$ w
18:54  up 22 days, 22:47, 6 users, load averages: 1.88 2.01 2.06
USER     TTY      FROM              LOGIN@  IDLE WHAT
apple    console  -                30 116  22days -
apple    s000     -                30 116  3days python manage.py shell
apple    s001     -                01 216  3days ./src/redis-server *:6379
apple    s002     -                01 216      - w
apple    s004     -                03 216      3 -bash
apple    s005     -                04 216  3days mongo

appledeMacBook-Pro:~ apple$ who
apple    console  Jan 30 20:07
apple    ttys000  Jan 30 20:07
apple    ttys001  Feb  1 10:01
apple    ttys002  Feb  1 10:19
apple    ttys004  Feb  3 10:00
apple    ttys005  Feb  4 12:18

用last查看每个账户最近登陆时间

appledeMacBook-Pro:~ apple$ last
apple     ttys003  10.0.1.74        Thu Feb 18 15:46 - 15:47  (00:01)
apple     ttys006                   Sat Feb  6 21:57 - 21:57  (00:00)
apple     ttys006                   Sat Feb  6 21:57 - 21:57  (00:00)
apple     ttys005                   Thu Feb  4 12:18   still logged in