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Linux命令详解之w命令
1.命令详解
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NAME
w - Show who is logged on and what they are doing.
w命令就是用来展示谁在登录，以及他们在做什么。
DESCRIPTION
w displays information about the users currently on the machine, and their processes. The header shows, in this order, the current time, how long the system has been running, how many
users are currently logged on, and the system load averages for the past 1, 5, and 15 minutes.
The following entries are displayed for each user: login name, the tty name, the remote host, login time, idle time, JCPU, PCPU, and the command line of their current process.
The JCPU time is the time used by all processes attached to the tty. It does not include past background jobs, but does include currently running background jobs.
The PCPU time is the time used by the current process, named in the "what" field.
w描述信息关于users当前在机器中的users，以及它们的进程。行首将以下面这个顺序展示：当前的时间，系统已经运行了多久，当前系统有多少用户在登录，系统在过去的1,5,15分钟的平均负载。
接下来的条目展示每个用户：登录名，tty 名，远程的（登录）主机，登录时间，空闲时间，JCPU，PCPU，以及当前进程的命令行。
JCPU时间是附加到所有的进程的使用时间。它不包括过去的后台程序，但是包括当前正在运行的后台程序。【不太理解】
PCPU时间是当前线程使用的时间，并在what域中展示出来。
```shell
COMMAND-LINE OPTIONS
-h, --no-header
Don't print the header.
-u, --no-current
Ignores the username while figuring out the current process and cpu times. To demonstrate this, do a "su" and do a "w" and a "w -u".
-s, --short
Use the short format. Don't print the login time, JCPU or PCPU times.
-f, --from
Toggle printing the from (remote hostname) field. The default as released is for the from field to not be printed, although your system administrator or distribution maintainer may
have compiled a version in which the from field is shown by default.
--help Display help text and exit.
-i, --ip-addr
Display IP address instead of hostname for from field.
-V, --version
Display version information.
-o, --old-style
Old style output. Prints blank space for idle times less than one minute.
user Show information about the specified user only.