Linux and Unix w command
The w command is a quick way to see who is logged on and what they are doing.
w displays information about the users currently on the machine, and their processes.
The header of the the output 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 they are logged in from, the amount of time they have been logged in, their 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 [options] user [...]
|-h, --no-header||Don't print the header.|
|-u, --no-current||Ignores the username while figuring out the current process and cpu times. (To see an example of this, switch to the root user with "su" and then run both "w" and "w -u".)|
|-s, --short||Display abbreviated output (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 a help message, and exit.|
|-V, --version||Display version information, and exit.|
|-o, --old-style||Old style output (prints blank space for idle times less than one minute).|
|user||Show information about the specified user user only.|
|PROCPS_USERLEN||The value of this environment variable, if set, will override the default width (8) of the username column.|
|PROCPS_FROMLEN||The value of this environment variable, if set, will override the default width (16) of the from column.|
|/var/run/utmp||This file stores the information about who is currently logged on.|
|/proc||System process information.|
Running the w command with no arguments will show a list of logged on users and their processes as shown below.
Show information for the user named chope.
free — Display the amount of free and used memory.
ps — Report the status of a process or processes.
top — Display a sortable, continually-updated list of processes.
uptime — Display information about how long the system has been running.
who — Report which users are logged in to the system.