Linux System Status Utilities
uptime

This command displays a one line summary showing...

Example: uptime
11:42pm up 18 days, 8:45, 1 user, load average: 0.00, 0.00, 0.00

  • Current time (11.42pm)
  • Number of days since last boot (up 18 days)
  • Number of users logged in (1 user)
  • System utilization for the last 1, 5 and 15 minute intervals (load average

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who

This command will display...

  • All users logged in
  • tty device(line) they are using
  • When they logged in
  • Idle time
  • Where they logged in from

Options:

  • -i display idle time
  • -H print column headings

Example: who -iH

USER LINE LOGIN-TIME IDLE FROM
roger ttyp0 Jun 5 23:27 . (omni)

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id

This command displays a one line summary for the current user listing...

  • user name and number
  • primary group and number
  • other groups and numbers

    Example: id
    uid=1000(roger) gid=100(users) groups=100(users),16(dialout),40(game)

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free

This command displays statistics on memory usage. The values represent KB's.

Example...

total used free shared buffers cached
Mem: 63208 61484 1724 27848 1060 49360
-/+ buffers/cache: 11064 52144
Swap: 128516 6500 122016

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du

This command stands for disk usage and will print the size of the current directory and subdirectories in 1 KB sizes.

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df

This command displays information for each file system.

Example: df

Filesystem 1024-blocks Used Available Capacity Mounted on
/dev/sda1 497667 301229 170736 64% /
/dev/sda2 7469935 5721885 1360884 81% /usr

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env

This command lists all shell (environment) variables and their contents for the current user.

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ps

This command lists process status. There are many options for this command. Below are the two most common.

Example: ps u  (process status for current user)

USER PID %CPU %MEM SIZE RSS TTY STAT START TIME COMMAND
roger 418 0.0 1.7 1808 1124 p0 S 23:27 0:01 -bash
roger 690 0.0 0.5 872 356 p0 R 00:09 0:00 ps u
  • PID = Unique Process ID
  • SIZE = Virtual image size; size of text+data+stack
  • RSS = Resident set size; kilobytes of program in memory
  • TTY = Controlling tty
  • STAT = Information about the status of the process
    • R = runnable
    • S = sleeping
    • D = uninterruptible sleep
    • T = stopped or traced
    • Z = zombie process
    • Second field = W if the process has no resident pages.
    • Third field = N if the process has a positive nice value

Example: ps ax (process status of all processes for all users and system)

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top

This command display a full screen of information of the top processes. It will update automatically until the program is stopped. To stop the display, enter q.

12:26am up 18 days 9:29 1 user load average: 0.00, 0.00, 0.00
39 processes: 38 sleeping, 1 running, 0 zombie, 0 stopped
CPU states: 0.5% user, 0.0% system, 0.0% nice, 99.5% idle
Mem: 63208K av, 60848K used, 2360K free, 271
Swap: 128516K av, 6500K used, 122016K free,  48696K cached
PID USER PRI NI SIZE RSS SHARE STAT LIB %CPU %MEM TIME COMMAND
769 roger 19 0 584 584 428 R 0 0.5 0.9 0:00 top
1 root 0 0 256 232 196 S 0 0.0 0.3 0:02 init
2 root 0 0 0 0 0 SW 0 0.0 0.0 0:03 kflushd
3 root -12 -12 0 0 0 SW< 0 0.0 0.0 0:00 kswapd
31485 root 0 0 288 288 232 S 0 0.0 0.4 0:00 mingetty
428 root 0 0 252 224 196 S 0 0.0 0.3 0:00 mingetty
142 root 0 0 264 208 208 S 0 0.0 0.3 0:00 mingetty
9 root 0 0 224 188 172 S 0 0.0 0.2 0:21 update
61 root 0 0 348 308 256 S 0 0.0 0.4 0:31 syslogd
59 root 0 0 464 412 232 S 0 0.0 0.6 0:00 klogd
130 root 0 0 1192 1092 932 S 0 0.0 1.7 0:00 _upsd
73 root 0 0 836 800 352 S 0 0.0 1.2 0:12 named
87 root 0 0 2484 1756 1612 S 0 0.0 2.7 0:00 httpd
90 at 0 0 288 248 224 S 0 0.0 0.3 0:00 atd
93 root 0 0 324 292 244 S 0 0.0 0.4 0:00 cron
96 root 0 0 308 292 228 S 0 0.0 0.4 0:05 inetd
105 root 0 0 324 292 236 S 0 0.0 0.4 0:00 lpd
31763 root 0 0 412 412 328 S 0 0.0 0.6 0:00 mgetty

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System Info - procinfo

procinfo gathers some system data from the /proc directory and prints it formatted on the screen.

Some of the information displayed is

  • Last Boot time
  • Load Average
  • average number of jobs running
  • number of runnable processes
  • total number of processes
  • PID of the last process run (idem)
  • Swap info
  • Memory resources
  • Number of disks
  • IRQ info
  • Installed modules (with the -a or -m option)
  • File Systems (with the -a or -m option)

    To automatically update the displayed info every 30 seconds

procinfo -fn30
To exit, simply press q

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