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diff --git a/slackbook/html/process-control-ps.html b/slackbook/html/process-control-ps.html new file mode 100644 index 000000000..27b842686 --- /dev/null +++ b/slackbook/html/process-control-ps.html @@ -0,0 +1,243 @@ +<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" + "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> +<html xmlns="http://www.w3.org/1999/xhtml"> +<head> +<meta name="generator" content="HTML Tidy, see www.w3.org" /> +<title>ps</title> +<meta name="GENERATOR" content="Modular DocBook HTML Stylesheet Version 1.7" /> +<link rel="HOME" title="Slackware Linux Essentials" href="index.html" /> +<link rel="UP" title="Process Control" href="process-control.html" /> +<link rel="PREVIOUS" title="Foregrounding" href="process-control-foregrounding.html" /> +<link rel="NEXT" title="kill" href="process-control-kill.html" /> +<link rel="STYLESHEET" type="text/css" href="docbook.css" /> +<meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1" /> +</head> +<body class="SECT1" bgcolor="#FFFFFF" text="#000000" link="#0000FF" vlink="#840084" +alink="#0000FF"> +<div class="NAVHEADER"> +<table summary="Header navigation table" width="100%" border="0" cellpadding="0" +cellspacing="0"> +<tr> +<th colspan="3" align="center">Slackware Linux Essentials</th> +</tr> + +<tr> +<td width="10%" align="left" valign="bottom"><a href="process-control-foregrounding.html" +accesskey="P">Prev</a></td> +<td width="80%" align="center" valign="bottom">Chapter 11 Process Control</td> +<td width="10%" align="right" valign="bottom"><a href="process-control-kill.html" +accesskey="N">Next</a></td> +</tr> +</table> + +<hr align="LEFT" width="100%" /> +</div> + +<div class="SECT1"> +<h1 class="SECT1"><a id="PROCESS-CONTROL-PS" name="PROCESS-CONTROL-PS">11.3 <tt +class="COMMAND">ps</tt></a></h1> + +<p>So now you know how to switch back and forth between several processes that you've +started from the command line. And you also know that there are lots of processes running +all the time. So how do you list all of these programs? Well, you make use of the <tt +class="COMMAND">ps</tt>(1) command. This command has a lot of options, so we'll only +cover the most important ones here. For a complete listing, see the man page for ps. Man +pages are covered in-depth in <a href="help.html#HELP-SYSTEM-MAN">Section 2.1.1</a>.</p> + +<p>Simply typing <tt class="COMMAND">ps</tt> will get you a listing of the programs +running on your terminal. This incudes the foreground processes (which include whatever +shell you are using, and of course, <tt class="COMMAND">ps</tt> itself). Also listed are +backgrounded processes you may have running. Many times, that will be a very short +listing:</p> + +<div class="FIGURE"><a id="FIG-PROCESS-CONTROL-PS-SHORT" +name="FIG-PROCESS-CONTROL-PS-SHORT"></a> +<p><b>Figure 11-1. Basic <tt class="COMMAND">ps</tt> output</b></p> + +<table border="0" bgcolor="#E0E0E0" width="100%"> +<tr> +<td> +<pre class="SCREEN"> +<samp class="PROMPT">%</samp> <kbd class="USERINPUT">ps</kbd> + PID TTY TIME CMD + 7923 ttyp0 00:00:00 bash + 8059 ttyp0 00:00:00 ps +</pre> +</td> +</tr> +</table> +</div> + +<p>Even though this is not a lot of processes, the information is very typical. You'll +get the same columns using regular ps no matter how many processes are running. So what +does it all mean?</p> + +<p>Well, the <var class="LITERAL">PID</var> is the <span class="emphasis"><i +class="EMPHASIS">process ID</i></span>. All running processes are given a unique +identifier which ranges between 1 and 32767. Each process is assigned the next free PID. +When a process quits (or is killed, as you will see in the next section), it gives up its +PID. When the max PID is reached, the next free one will wrap back around to the lowest +free one.</p> + +<p>The <var class="LITERAL">TTY</var> column indicates which terminal the process is +running on. Doing a plain <tt class="COMMAND">ps</tt> will only list all the programs +running on the current terminal, so all the processes give the same information in the +TTY column. As you can see, both processes listed are running on <tt +class="FILENAME">ttyp0</tt>. This indicates that they are either running remotely or from +an X terminal of some variety.</p> + +<p>The <var class="LITERAL">TIME</var> column indicated how much CPU time the process has +been running. This is different from the actual amount of time that a process runs. +Remember that Linux is a multitasking operating system. There are many processes running +all the time, and these processes each get a small portion of the processor's time. So, +the TIME column should show much less time for each process than it actually takes to +run. If you see more than several minutes in the TIME column, it could mean that +something is wrong.</p> + +<p>Finally, the <var class="LITERAL">CMD</var> column shows what the program actually is. +It only lists the base name of the program, not any command line options or similar +information. To get that information, you'll need to use one of the many options to <tt +class="COMMAND">ps</tt>. We'll discuss that shortly.</p> + +<p>You can get a complete listing of the processes running on your system using the right +combination of options. This will probably result in a long listing of processes +(fifty-five on my laptop as I write this sentence), so I'll abbreviate the output:</p> + +<table border="0" bgcolor="#E0E0E0" width="100%"> +<tr> +<td> +<pre class="SCREEN"> +<samp class="PROMPT">%</samp> <kbd class="USERINPUT">ps -ax</kbd> + PID TTY STAT TIME COMMAND + 1 ? S 0:03 init [3] + 2 ? SW 0:13 [kflushd] + 3 ? SW 0:14 [kupdate] + 4 ? SW 0:00 [kpiod] + 5 ? SW 0:17 [kswapd] + 11 ? S 0:00 /sbin/kerneld + 30 ? SW 0:01 [cardmgr] + 50 ? S 0:00 /sbin/rpc.portmap + 54 ? S 0:00 /usr/sbin/syslogd + 57 ? S 0:00 /usr/sbin/klogd -c 3 + 59 ? S 0:00 /usr/sbin/inetd + 61 ? S 0:04 /usr/local/sbin/sshd + 63 ? S 0:00 /usr/sbin/rpc.mountd + 65 ? S 0:00 /usr/sbin/rpc.nfsd + 67 ? S 0:00 /usr/sbin/crond -l10 + 69 ? S 0:00 /usr/sbin/atd -b 15 -l 1 + 77 ? S 0:00 /usr/sbin/apmd + 79 ? S 0:01 gpm -m /dev/mouse -t ps2 + 94 ? S 0:00 /usr/sbin/automount /auto file /etc/auto.misc + 106 tty1 S 0:08 -bash + 108 tty3 SW 0:00 [agetty] + 109 tty4 SW 0:00 [agetty] + 110 tty5 SW 0:00 [agetty] + 111 tty6 SW 0:00 [agetty] + [output cut] +</pre> +</td> +</tr> +</table> + +<p>Most of these processes are started at boot time on most systems. I've made a few +modifications to my system, so your mileage will most likely vary. However, you will see +most of these processes on your system too. As you can see, these options display command +line options to the running processes. Recently, a kernel vulnerability in <tt +class="COMMAND">ptrace</tt> facilitated a fix which no longer shows command line options +for many running processes. These are now listed in brackets like PIDs 108 through 110. +It also brings up a few more columns and some other interesting output.</p> + +<p>First, you'll notice that most of these processes are listed as running on tty +“?”. Those are not attached to any particular terminal. This is most common +with daemons, which are processes which run without attaching to any particular terminal. +Common daemons are sendmail, BIND, apache, and NFS. They typically listen for some +request from a client, and return information to it upon request.</p> + +<p>Second, there is a new column: <var class="LITERAL">STAT</var>. It shows the status of +the process. <var class="LITERAL">S</var> stands for sleeping: the process is waiting for +something to happen. <var class="LITERAL">Z</var> stands for a zombied process. A zombied +processes is one whose parent has died, leaving the child processes behind. This is not a +good thing. <var class="LITERAL">D</var> stands for a process that has entered an +uninterruptible sleep. Often, these processes refuse to die even when passed a SIGKILL. +You can read more about SIGKILL later in the next section on <tt +class="COMMAND">kill</tt> . W stands for paging. A dead process is marked with an <var +class="LITERAL">X</var>. A process marked <var class="LITERAL">T</var> is traced, or +stopped. <var class="LITERAL">R</var> means that the process is runable.</p> + +<p>If you want to see even more information about the running processes, try this +out:</p> + +<table border="0" bgcolor="#E0E0E0" width="100%"> +<tr> +<td> +<pre class="SCREEN"> +<samp class="PROMPT">%</samp> <kbd class="USERINPUT">ps -aux</kbd> + USER PID %CPU %MEM VSZ RSS TTY STAT START TIME COMMAND + root 1 0.0 0.0 344 80 ? S Mar02 0:03 init [3] + root 2 0.0 0.0 0 0 ? SW Mar02 0:13 [kflushd] + root 3 0.0 0.0 0 0 ? SW Mar02 0:14 [kupdate] + root 4 0.0 0.0 0 0 ? SW Mar02 0:00 [kpiod] + root 5 0.0 0.0 0 0 ? SW Mar02 0:17 [kswapd] + root 11 0.0 0.0 1044 44 ? S Mar02 0:00 /sbin/kerneld + root 30 0.0 0.0 1160 0 ? SW Mar02 0:01 [cardmgr] + bin 50 0.0 0.0 1076 120 ? S Mar02 0:00 /sbin/rpc.port + root 54 0.0 0.1 1360 192 ? S Mar02 0:00 /usr/sbin/sysl + root 57 0.0 0.1 1276 152 ? S Mar02 0:00 /usr/sbin/klog + root 59 0.0 0.0 1332 60 ? S Mar02 0:00 /usr/sbin/inet + root 61 0.0 0.2 1540 312 ? S Mar02 0:04 /usr/local/sbi + root 63 0.0 0.0 1796 72 ? S Mar02 0:00 /usr/sbin/rpc. + root 65 0.0 0.0 1812 68 ? S Mar02 0:00 /usr/sbin/rpc. + root 67 0.0 0.2 1172 260 ? S Mar02 0:00 /usr/sbin/cron + root 77 0.0 0.2 1048 316 ? S Mar02 0:00 /usr/sbin/apmd + root 79 0.0 0.1 1100 152 ? S Mar02 0:01 gpm + root 94 0.0 0.2 1396 280 ? S Mar02 0:00 /usr/sbin/auto + chris 106 0.0 0.5 1820 680 tty1 S Mar02 0:08 -bash + root 108 0.0 0.0 1048 0 tty3 SW Mar02 0:00 [agetty] + root 109 0.0 0.0 1048 0 tty4 SW Mar02 0:00 [agetty] + root 110 0.0 0.0 1048 0 tty5 SW Mar02 0:00 [agetty] + root 111 0.0 0.0 1048 0 tty6 SW Mar02 0:00 [agetty] + [output cut] +</pre> +</td> +</tr> +</table> + +<p>That's a whole lot of information. Basically, it adds information including what user +started the process, how much of the system resources the process is using (the %CPU, +%MEM, VSZ, and RSS columns), and on what date the process was started. Obviously, that's +a lot of information that could come in handy for a system administrator. It also brings +up another point: the information now goes off the edge of the screen so that you cannot +see it all. The <var class="OPTION">-w</var> option will force <tt +class="COMMAND">ps</tt> to wrap long lines.</p> + +<p>It's not terribly pretty, but it does the job. You've now got the complete listings +for each process. There's even more information that you can display about each process. +Check out the very in-depth man page for <tt class="COMMAND">ps</tt>. However, the +options shown above are the most popular ones and will be the ones you need to use the +most often.</p> +</div> + +<div class="NAVFOOTER"> +<hr align="LEFT" width="100%" /> +<table summary="Footer navigation table" width="100%" border="0" cellpadding="0" +cellspacing="0"> +<tr> +<td width="33%" align="left" valign="top"><a href="process-control-foregrounding.html" +accesskey="P">Prev</a></td> +<td width="34%" align="center" valign="top"><a href="index.html" +accesskey="H">Home</a></td> +<td width="33%" align="right" valign="top"><a href="process-control-kill.html" +accesskey="N">Next</a></td> +</tr> + +<tr> +<td width="33%" align="left" valign="top">Foregrounding</td> +<td width="34%" align="center" valign="top"><a href="process-control.html" +accesskey="U">Up</a></td> +<td width="33%" align="right" valign="top"><tt class="COMMAND">kill</tt></td> +</tr> +</table> +</div> +</body> +</html> + |