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> > > newbie: System Monitoring commands - du, df, ps, top, who, w, free. > Date: 24-Dec-99 > Author: cogNiTioN <cognition@bigfoot.com> > > System Monitoring Commands > > This file goes through some commands that can let you know what your system > is doing. Using these commands you can tell what programs are running, how > much memory or how many cpu cycles those programs are using, who's logged > in, where from, how long they've been logged in for and more. These > commands also deal with how much disk space or memory is being used. > > Bear in mind that this is not a detailed look at each command, it is an > overview only. > > ------------------------------------------------------------------------- > > Command: du > > This command prints the disk usage (in Kb) of each directory and it's sub > directories. By default it starts from the current directory, but supplying > the name of a directory after the command will make it start from that > directory. > > cognition@pingu:/usr/cog $ du > > 126 ./Mail/.archived/.pgp > 18851 ./Mail/.archived > 21016 ./Mail > 2247 ./zip > 80 ./.pgp > 15 ./develop/getmail/bup > 35 ./develop/getmail > 36 ./develop > 2300 ./.procmail > ~~ > <SNIPPED FULL OUTPUT OF COMMAND, FOR BREVITY> > ~~ > 31678 . > > cognition@pingu:/usr/cog $ du Mail > > 126 Mail/.archived/.pgp > 18851 Mail/.archived > 21016 Mail > > cognition@pingu:/usr/cog $ du /root > > du: /root: Permission denied > > > As the last example shows, you can only show the disk usage for > directories (or subdirectories) that you have execute permissions on. > > Options: (these may vary depending on version run, and there are more ;) > -a (--all) Prints usage for ALL files, not just the subdirectories > -b (--bytes) Prints usage in bytes rather than Kb. > -s (--summarize) Prints ONLY the total usage of the directory > > Consult 'man du' for more details on usage > > ------------------------------------------------------------------------- > > Command: df > > This command tells you the amount of free space on all mounted file systems, > or you can specify the name of a device you want to check, (the device has > to be mounted, though). > > cognition@pingu:/usr/cog $ df > > Filesystem 1024-blocks Used Available Capacity Mounted on > /dev/hdb1 483038 358274 99816 78% / > /dev/hda1 246854 14293 219812 6% /home > /dev/sda4 98078 96752 1326 99% /zip > > cognition@pingu:/usr/cog $ df /dev/hdb1 > > Filesystem 1024-blocks Used Available Capacity Mounted on > /dev/hdb1 483038 358274 99816 78% / > > > I currently have 3 file systems mounted (2 internal Hard Discs and a zip > disc). The second column (labeled 1024-blocks) shows the total size (in Kb) > of the corresponding file system, the third column shows how much space has > been used, column four gives the remaining space and column five (Capacity) > shows (as a percentage how much of the space has been used. The last column > simply shows the mount point of that file system. > > for more information see 'man df' > > ------------------------------------------------------------------------- > > Command: ps > > 'ps' shows you what processes (programs) you have running (or are running > with your user id). > > cognition@pingu:/usr/cog $ ps > > PID TTY STAT TIME COMMAND > 32042 1 S 0:04 -bash > 32068 2 S 0:04 (bash) > 32168 2 S 1:07 vi admin101 > 32415 2 S 0:00 /bin/bash -c (ps) >/tmp/voa32168 2>&1 > 32416 2 R 0:00 ps > > > It's interesting to note the second line up from the bottom; that's what > vi sends out when I get it to execute a command for me. > > Note: When using options with ps, you do not need to include a leading > '-' sign, while this is still accepted, it's use is "deprecated". > > A good set of options to use is 'aux'. The command 'ps aux' gives you a > surplus of information about all the processes running on your system. Note > you do not need to be 'root' to run 'ps aux', you can do so as a normal user > and still get a full listing of processes. The output from 'ps aux' is > similar to that from the 'top' command, which is covered below, except that > 'ps aux' is a snap shot, and is not updated. > > See 'man ps' for more information. > > ------------------------------------------------------------------------- > > Command: who > > As Unix is a multi-user operating system, there can be more than one > person using the machine at any given time. How do you find out how many > users your system currently has? You ask the system, that's how. The 'who' > command shows you who has logged in, where they're logged into and when > they logged in. > > > cognition@pingu:/usr/cog $ who > > cognitio tty1 Sep 6 14:23 > cognitio tty2 Sep 6 18:01 > root tty5 Sep 6 18:18 > > > 'who' can also tell you who you are, when run as 'who am i', this is the > same as the command 'whoami'. > > For more information, including other options, see 'man who' > > ------------------------------------------------------------------------- > > Command: w > > The 'w' command is really the output of 'uptime', 'who' and 'ps a' combined > to give a comprehensive system usage summary. To give the usage of one > user, just give the user's name after the command. > > > cognition@pingu:/usr/cog $ w > 9:29pm up 45 days, 9:59, 4 users, load average: 1.06, 0.97, 0.92 > USER TTY FROM LOGIN@ IDLE JCPU PCPU WHAT > cognitio tty1 2:23pm 1:54 6.01s 0.70s -bash > cognitio tty2 6:01pm 3.00s 1:45 1:39 vi admin101 > root tty5 6:18pm 36:09 4.35s 4.35s -bash > > cognition@pingu:/usr/cog $ w root > 9:29pm up 45 days, 10:00, 4 users, load average: 1.16, 1.01, 0.93 > USER TTY FROM LOGIN@ IDLE JCPU PCPU WHAT > root tty5 6:18pm 36:56 4.35s 4.35s -bash > > > > Notice that most entries don't have an entry in the FROM column, this > indicates that they're logged on from the console (i.e. they have physical > access to the machine). > > See 'man w' for more details. > > ------------------------------------------------------------------------- > > Command: free > > 'free' shows you information about the machine's memory. This includes > physical memory (RAM), swap as well as the shared memory and buffers > used by the kernal. All measurements are in Kb. > > > cognition@pingu:/usr/cog $ free > total used free shared buffers cached > Mem: 10672 10168 504 4912 172 3000 > -/+ buffers/cache: 6996 3676 > Swap: 33228 18068 15160 > > > > For more information, and a list of options, see 'man free' > > ------------------------------------------------------------------------- > > Command: top > > 'top' provides lots of information on the processes running, including the > percentage of the cpu and the memory being consumed by that process, who > 'owns' the process and it's pid (Process ID), it also shows the output of > 'uptime' and a summary of memory usage, similar to 'free'. The output of > 'top' is full screen, and refreshes itself frequently (or at user definable > intervals). > > Here is a representation of the output from 'top': > > cognition@pingu:/usr/cog $ top > > 11:42pm up 45 days, 12:13, 9 users, load average: 1.66, 1.52, 1.20 > 66 processes: 64 sleeping, 2 running, 0 zombie, 0 stopped > CPU states: 84.5% user, 36.1% system, 0.0% nice, 0.0% idle > Mem: 10672K av, 10276K used, 396K free, 5660K shrd, 212K buff > Swap: 33228K av, 18976K used, 14252K free 2556K cached > > PID USER PRI NI SIZE RSS SHARE STAT LIB %CPU %MEM TIME COMMAND > 216 root 10 0 376 324 192 S 0 32.5 3.0 13267m top > 32609 cognitio 9 0 584 584 420 S 0 31.7 5.4 0:29 top > 213 root 20 0 696 596 124 R 0 28.5 5.5 28197m smartbee > 32612 cognitio 15 0 580 580 416 R 0 26.6 5.4 0:03 top > 32469 root 1 0 208 112 88 S 0 0.7 1.0 0:15 in.telnetd > 3 root -12 -12 0 0 0 SW< 0 0.1 0.0 3:19 kswapd > 15 root 0 0 84 48 32 S 0 0.1 0.4 18:06 update > 32468 cognitio 0 0 204 108 72 S 0 0.1 1.0 0:16 telnet > 1 root 0 0 88 48 24 S 0 0.0 0.4 0:19 init > 2 root 0 0 0 0 0 SW 0 0.0 0.0 1:01 kflushd > 4 root 0 0 0 0 0 SW 0 0.0 0.0 0:00 nfsiod > 5 root 0 0 0 0 0 SW 0 0.0 0.0 0:00 nfsiod > 6 root 0 0 0 0 0 SW 0 0.0 0.0 0:00 nfsiod > 7 root 0 0 0 0 0 SW 0 0.0 0.0 0:00 nfsiod > 32042 cognitio 0 0 448 32 32 S 0 0.0 0.2 0:05 bash > 32068 cognitio 0 0 408 0 0 SW 0 0.0 0.0 0:04 bash > 32071 cognitio 0 0 456 28 28 S 0 0.0 0.2 0:06 bash > > For more information, see 'man top' > > ------------------------------------------------------------------------- > > See also: > Linux in a Nutshell (O'Reilly) > The Man pages for relevent commands > > Please direct any feedback relating to this file to me, via email to: > <cognition@bigfoot.com> > > ------------------------------------------------------------------------- > cogNiTioN <cognition@bigfoot.com> > Copyright 1999 cogNiTioN >
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