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Linux 小知识 丨who、时区命令

Who 命令

who - [husfV] [user] 显示当前登录系统的用户

[root@VM-8-10-centos ~]# who
root     pts/0        2021-11-04 14:22 (124.128.97.210)

[root@VM-8-10-centos ~]# who --help
Usage: who [OPTION]... [ FILE | ARG1 ARG2 ]
Print information about users who are currently logged in.

  -a, --all         same as -b -d --login -p -r -t -T -u
  -b, --boot        time of last system boot
  -d, --dead        print dead processes
  -H, --heading     print line of column headings # 显示标题信息
  -l, --login       print system login processes
      --lookup      attempt to canonicalize hostnames via DNS
  -m                only hostname and user associated with stdin
  -p, --process     print active processes spawned by init
  -q, --count       all login names and number of users logged on # 只显示登入系统的账号名称和总人数
  -r, --runlevel    print current runlevel
  -s, --short       print only name, line, and time (default) # 此参数将忽略不予处理,仅负责解决who指令其版本的兼容性问题
  -w								# 显示用户的信息状态栏
 -t, --time        print last system clock change
  -T, -w, --mesg    add user's message status as +, - or ?
  -u, --users       list users logged in # 显示闲置时间,如果一份之后有操作,则显示点,如果超过24小时误操作,则显示old字符串
      --message     same as -T
      --writable    same as -T
      --help     display this help and exit
      --version  output version information and exi

[root@VM-8-10-centos ~]# who -w   # 显示用户的信息状态栏
root     + pts/0        2021-11-04 14:22 (124.128.97.210)
[root@VM-8-10-centos ~]# who -H # 显示明细(标题)信息
NAME     LINE         TIME             COMMENT
root     pts/0        2021-11-04 14:22 (124.128.97.210

timedatectl 命令

校正服务器时间、时区

[root@VM-8-10-centos ~]# timedatectl --help
timedatectl [OPTIONS...] COMMAND ...

Query or change system time and date settings.

  -h --help                Show this help message
     --version             Show package version
     --no-pager            Do not pipe output into a pager
     --no-ask-password     Do not prompt for password
  -H --host=[USER@]HOST    Operate on remote host
  -M --machine=CONTAINER   Operate on local container
     --adjust-system-clock Adjust system clock when changing local RTC mode
     --monitor             Monitor status of systemd-timesyncd
  -p --property=NAME       Show only properties by this name
  -a --all                 Show all properties, including empty ones
     --value               When showing properties, only print the value

Commands:
  status                   Show current time settings
  show                     Show properties of systemd-timedated
  set-time TIME            Set system time
  set-timezone ZONE        Set system time zone
  list-timezones           Show known time zones
  set-local-rtc BOOL       Control whether RTC is in local time
  set-ntp BOOL             Enable or disable network time synchronization

systemd-timesyncd Commands:
  timesync-status          Show status of systemd-timesyncd
  show-timesync            Show properties of systemd-timesyncd

与 ntp时间服务器 同步

timedatectl set-ntp true

[root@VM-8-10-centos ~]# timedatectl  || timedatectl status
               Local time: 四 2021-11-04 15:46:12 CST #本地时间, 操作系统时间 背景时间
           Universal time: 四 2021-11-04 07:46:12 UTC #世界标准时间UTF 8小时时差
                 RTC time: 四 2021-11-04 07:46:11 #主板时间
                Time zone: Asia/Shanghai (CST, +0800) # 时区
System clock synchronized: yes # ntp 开启同步
              NTP service: active
          RTC in local TZ: no

查看可选择的时区

timedatectl list-timezones

timedatectl set-timezone "Asia/Shanghai" #设置时区
timedatectl set-ntp true #开启ntp
timedatectl set-ntp false #禁用ntp
timedatectl set-time "2030-01-01 00:00:00" #禁用ntp后可以设置时间

clear 命令

清除屏幕