D7net Mini Sh3LL v1
| Current File : //usr/share/systemd/../doc/python3-configobj/../php7.4-gd/../time/time.html |
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<!-- Created by GNU Texinfo 6.3, http://www.gnu.org/software/texinfo/ -->
<head>
<title>Measuring Program Resource Use</title>
<meta name="description" content="Measuring Program Resource Use">
<meta name="keywords" content="Measuring Program Resource Use">
<meta name="resource-type" content="document">
<meta name="distribution" content="global">
<meta name="Generator" content="makeinfo">
<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
<link href="#Top" rel="start" title="Top">
<link href="#Concept-index" rel="index" title="Concept index">
<link href="#SEC_Contents" rel="contents" title="Table of Contents">
<link href="dir.html#Top" rel="up" title="(dir)">
<style type="text/css">
<!--
a.summary-letter {text-decoration: none}
blockquote.indentedblock {margin-right: 0em}
blockquote.smallindentedblock {margin-right: 0em; font-size: smaller}
blockquote.smallquotation {font-size: smaller}
div.display {margin-left: 3.2em}
div.example {margin-left: 3.2em}
div.lisp {margin-left: 3.2em}
div.smalldisplay {margin-left: 3.2em}
div.smallexample {margin-left: 3.2em}
div.smalllisp {margin-left: 3.2em}
kbd {font-style: oblique}
pre.display {font-family: inherit}
pre.format {font-family: inherit}
pre.menu-comment {font-family: serif}
pre.menu-preformatted {font-family: serif}
pre.smalldisplay {font-family: inherit; font-size: smaller}
pre.smallexample {font-size: smaller}
pre.smallformat {font-family: inherit; font-size: smaller}
pre.smalllisp {font-size: smaller}
span.nolinebreak {white-space: nowrap}
span.roman {font-family: initial; font-weight: normal}
span.sansserif {font-family: sans-serif; font-weight: normal}
ul.no-bullet {list-style: none}
-->
</style>
</head>
<body lang="en">
<h1 class="settitle" align="center">Measuring Program Resource Use</h1>
<a name="SEC_Contents"></a>
<h2 class="contents-heading">Table of Contents</h2>
<div class="contents">
<ul class="no-bullet">
<li><a name="toc-Measuring-Program-Resource-Use" href="#Resource-Measurement">1 Measuring Program Resource Use</a>
<ul class="no-bullet">
<li><a name="toc-Setting-the-Output-Format" href="#Setting-Format">1.1 Setting the Output Format</a></li>
<li><a name="toc-The-Format-String" href="#Format-String">1.2 The Format String</a>
<ul class="no-bullet">
<li><a name="toc-Time-Resources-1" href="#Time-Resources">1.2.1 Time Resources</a></li>
<li><a name="toc-Memory-Resources-1" href="#Memory-Resources">1.2.2 Memory Resources</a></li>
<li><a name="toc-I_002fO-Resources-1" href="#I_002fO-Resources">1.2.3 I/O Resources</a></li>
<li><a name="toc-Command-Info-1" href="#Command-Info">1.2.4 Command Info</a></li>
</ul></li>
<li><a name="toc-Redirecting-Output" href="#Redirecting">1.3 Redirecting Output</a></li>
<li><a name="toc-Examples-1" href="#Examples">1.4 Examples</a></li>
<li><a name="toc-Accuracy-1" href="#Accuracy">1.5 Accuracy</a></li>
<li><a name="toc-Running-the-time-Command" href="#Invoking-time">1.6 Running the <code>time</code> Command</a></li>
</ul></li>
<li><a name="toc-Concept-index-1" href="#Concept-index">Concept index</a></li>
</ul>
</div>
<a name="Top"></a>
<div class="header">
<p>
Next: <a href="#Resource-Measurement" accesskey="n" rel="next">Resource Measurement</a>, Up: <a href="dir.html#Top" accesskey="u" rel="up">(dir)</a> [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Concept-index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="The-GNU-time-Command"></a>
<h1 class="top">The GNU <code>time</code> Command</h1>
<table class="menu" border="0" cellspacing="0">
<tr><td align="left" valign="top">• <a href="#Resource-Measurement" accesskey="1">Resource Measurement</a>:</td><td> </td><td align="left" valign="top">Measuring program resource use.
</td></tr>
<tr><td align="left" valign="top">• <a href="#Concept-index" accesskey="2">Concept index</a>:</td><td> </td><td align="left" valign="top">Index of concepts.
</td></tr>
</table>
<hr>
<a name="Resource-Measurement"></a>
<div class="header">
<p>
Next: <a href="#Concept-index" accesskey="n" rel="next">Concept index</a>, Previous: <a href="#Top" accesskey="p" rel="prev">Top</a>, Up: <a href="#Top" accesskey="u" rel="up">Top</a> [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Concept-index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="Measuring-Program-Resource-Use"></a>
<h2 class="chapter">1 Measuring Program Resource Use</h2>
<a name="index-time-invocation"></a>
<a name="index-time"></a>
<a name="index-measurement"></a>
<p>The <code>time</code> command runs another program, then displays information
about the resources used by that program, collected by the system while
the program was running. You can select which information is reported
and the format in which it is shown (see <a href="#Setting-Format">Setting Format</a>), or have
<code>time</code> save the information in a file instead of displaying it on the
screen (see <a href="#Redirecting">Redirecting</a>).
</p>
<p>The resources that <code>time</code> can report on fall into the general
categories of time, memory, and I/O and IPC calls. Some systems do not
provide much information about program resource use; <code>time</code>
reports unavailable information as zero values (see <a href="#Accuracy">Accuracy</a>).
</p>
<p>The format of the <code>time</code> command is:
</p>
<div class="example">
<pre class="example">time <span class="roman">[</span>option…<span class="roman">]</span> <var>command</var> <span class="roman">[</span><var>arg</var>…<span class="roman">]</span>
</pre></div>
<a name="index-resource-specifiers"></a>
<p><code>time</code> runs the program <var>command</var>, with any given arguments
<var>arg</var>…. When <var>command</var> finishes, <code>time</code> displays
information about resources used by <var>command</var>.
</p>
<p>Here is an example of using <code>time</code> to measure the time and other
resources used by running the program <code>grep</code>:
</p>
<div class="example">
<pre class="example">eg$ time grep nobody /etc/aliases
nobody:/dev/null
etc-files:nobody
misc-group:nobody
0.07user 0.50system 0:06.69elapsed 8%CPU (0avgtext+489avgdata 324maxresident)k
46inputs+7outputs (43major+251minor)pagefaults 0swaps
</pre></div>
<p>Mail suggestions and bug reports for GNU <code>time</code> to
<code>bug-gnu-utils@gnu.org</code>. Please include the version of
<code>time</code>, which you can get by running ‘<samp>time --version</samp>’, and the
operating system and C compiler you used.
</p>
<table class="menu" border="0" cellspacing="0">
<tr><td align="left" valign="top">• <a href="#Setting-Format" accesskey="1">Setting Format</a>:</td><td> </td><td align="left" valign="top">Selecting the information reported by <code>time</code>.
</td></tr>
<tr><td align="left" valign="top">• <a href="#Format-String" accesskey="2">Format String</a>:</td><td> </td><td align="left" valign="top">The information <code>time</code> can report.
</td></tr>
<tr><td align="left" valign="top">• <a href="#Redirecting" accesskey="3">Redirecting</a>:</td><td> </td><td align="left" valign="top">Writing the information to a file.
</td></tr>
<tr><td align="left" valign="top">• <a href="#Examples" accesskey="4">Examples</a>:</td><td> </td><td align="left" valign="top">Examples of using <code>time</code>.
</td></tr>
<tr><td align="left" valign="top">• <a href="#Accuracy" accesskey="5">Accuracy</a>:</td><td> </td><td align="left" valign="top">Limitations on the accuracy of <code>time</code> output.
</td></tr>
<tr><td align="left" valign="top">• <a href="#Invoking-time" accesskey="6">Invoking time</a>:</td><td> </td><td align="left" valign="top">Summary of the options to the <code>time</code> command.
</td></tr>
</table>
<hr>
<a name="Setting-Format"></a>
<div class="header">
<p>
Next: <a href="#Format-String" accesskey="n" rel="next">Format String</a>, Up: <a href="#Resource-Measurement" accesskey="u" rel="up">Resource Measurement</a> [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Concept-index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="Setting-the-Output-Format"></a>
<h3 class="section">1.1 Setting the Output Format</h3>
<p><code>time</code> uses a <em>format string</em> to determine which information to
display about the resources used by the command it runs. See <a href="#Format-String">Format String</a>, for the interpretation of the format string contents.
</p>
<p>You can specify a format string with the command line options listed
below. If no format is specified on the command line, but the
<code>TIME</code> environment variable is set, its value is used as the format
string. Otherwise, the default format built into <code>time</code> is used:
</p>
<div class="example">
<pre class="example">%Uuser %Ssystem %Eelapsed %PCPU (%Xtext+%Ddata %Mmax)k
%Iinputs+%Ooutputs (%Fmajor+%Rminor)pagefaults %Wswaps
</pre></div>
<p>The command line options to set the format are:
</p>
<dl compact="compact">
<dt><code>-f <var>format</var></code></dt>
<dt><code>--format=<var>format</var></code></dt>
<dd><p>Use <var>format</var> as the format string.
</p>
</dd>
<dt><code>-p</code></dt>
<dt><code>--portability</code></dt>
<dd><p>Use the following format string:
</p>
<div class="example">
<pre class="example">real %e
user %U
sys %S
</pre></div>
<p>The default output format of time differs widely between
implementations. This option (in its short form -p) is supported by all
POSIX-compliant ’time’ implementations to retrieve basic information in
the described format.
</p>
</dd>
<dt><code>-q</code></dt>
<dt><code>--quiet</code></dt>
<dd><p>Suppress non-zero error code from the executed program.
</p>
</dd>
<dt><code>-v</code></dt>
<dt><code>--verbose</code></dt>
<dd><a name="index-verbose-format"></a>
<p>Use the built-in verbose format, which displays each available piece of
information on the program’s resource use on its own line, with an
English description of its meaning.
</p></dd>
</dl>
<hr>
<a name="Format-String"></a>
<div class="header">
<p>
Next: <a href="#Redirecting" accesskey="n" rel="next">Redirecting</a>, Previous: <a href="#Setting-Format" accesskey="p" rel="prev">Setting Format</a>, Up: <a href="#Resource-Measurement" accesskey="u" rel="up">Resource Measurement</a> [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Concept-index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="The-Format-String"></a>
<h3 class="section">1.2 The Format String</h3>
<a name="index-format"></a>
<p>The <em>format string</em> controls the contents of the <code>time</code> output.
It consists of <em>resource specifiers</em> and <em>escapes</em>, interspersed
with plain text.
</p>
<p>A backslash introduces an <em>escape</em>, which is translated
into a single printing character upon output. The valid escapes are
listed below. An invalid escape is output as a question mark followed
by a backslash.
</p>
<dl compact="compact">
<dt><code>\t</code></dt>
<dd><p>a tab character
</p>
</dd>
<dt><code>\n</code></dt>
<dd><p>a newline
</p>
</dd>
<dt><code>\\</code></dt>
<dd><p>a literal backslash
</p></dd>
</dl>
<p><code>time</code> always prints a newline after printing the resource use
information, so normally format strings do not end with a newline
character (or ‘<samp>\n</samp>’).
</p>
<p>A resource specifier consists of a percent sign followed by another
character. An invalid resource specifier is output as a question mark
followed by the invalid character. Use ‘<samp>%%</samp>’ to output a literal
percent sign.
</p>
<p>The resource specifiers, which are a superset of those recognized by the
<code>tcsh</code> builtin <code>time</code> command, are listed below. Not all
resources are measured by all versions of Unix, so some of the values
might be reported as zero (see <a href="#Accuracy">Accuracy</a>).
</p>
<table class="menu" border="0" cellspacing="0">
<tr><td align="left" valign="top">• <a href="#Time-Resources" accesskey="1">Time Resources</a>:</td><td> </td><td align="left" valign="top">
</td></tr>
<tr><td align="left" valign="top">• <a href="#Memory-Resources" accesskey="2">Memory Resources</a>:</td><td> </td><td align="left" valign="top">
</td></tr>
<tr><td align="left" valign="top">• <a href="#I_002fO-Resources" accesskey="3">I/O Resources</a>:</td><td> </td><td align="left" valign="top">
</td></tr>
<tr><td align="left" valign="top">• <a href="#Command-Info" accesskey="4">Command Info</a>:</td><td> </td><td align="left" valign="top">
</td></tr>
</table>
<hr>
<a name="Time-Resources"></a>
<div class="header">
<p>
Next: <a href="#Memory-Resources" accesskey="n" rel="next">Memory Resources</a>, Up: <a href="#Format-String" accesskey="u" rel="up">Format String</a> [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Concept-index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="Time-Resources-1"></a>
<h4 class="subsection">1.2.1 Time Resources</h4>
<dl compact="compact">
<dt><code>E</code></dt>
<dd><p>Elapsed real (wall clock) time used by the process, in
[hours:]minutes:seconds.
</p>
</dd>
<dt><code>e</code></dt>
<dd><p>Elapsed real (wall clock) time used by the process, in
seconds.
</p>
</dd>
<dt><code>S</code></dt>
<dd><p>Total number of CPU-seconds used by the system on behalf of the process
(in kernel mode), in seconds.
</p>
</dd>
<dt><code>U</code></dt>
<dd><p>Total number of CPU-seconds that the process used directly (in user
mode), in seconds.
</p>
</dd>
<dt><code>P</code></dt>
<dd><p>Percentage of the CPU that this job got. This is just user + system
times divied by the total running time.
</p></dd>
</dl>
<hr>
<a name="Memory-Resources"></a>
<div class="header">
<p>
Next: <a href="#I_002fO-Resources" accesskey="n" rel="next">I/O Resources</a>, Previous: <a href="#Time-Resources" accesskey="p" rel="prev">Time Resources</a>, Up: <a href="#Format-String" accesskey="u" rel="up">Format String</a> [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Concept-index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="Memory-Resources-1"></a>
<h4 class="subsection">1.2.2 Memory Resources</h4>
<dl compact="compact">
<dt><code>M</code></dt>
<dd><p>Maximum resident set size of the process during its lifetime, in
Kilobytes.
</p>
</dd>
<dt><code>t</code></dt>
<dd><p>Average resident set size of the process, in Kilobytes.
</p>
</dd>
<dt><code>K</code></dt>
<dd><p>Average total (data+stack+text) memory use of the process, in Kilobytes.
</p>
</dd>
<dt><code>D</code></dt>
<dd><p>Average size of the process’s unshared data area, in Kilobytes.
</p>
</dd>
<dt><code>p</code></dt>
<dd><p>Average size of the process’s unshared stack, in Kilobytes.
</p>
</dd>
<dt><code>X</code></dt>
<dd><p>Average size of the process’s shared text, in Kilobytes.
</p>
</dd>
<dt><code>Z</code></dt>
<dd><p>System’s page size, in bytes. This is a per-system constant, but
varies between systems.
</p></dd>
</dl>
<hr>
<a name="I_002fO-Resources"></a>
<div class="header">
<p>
Next: <a href="#Command-Info" accesskey="n" rel="next">Command Info</a>, Previous: <a href="#Memory-Resources" accesskey="p" rel="prev">Memory Resources</a>, Up: <a href="#Format-String" accesskey="u" rel="up">Format String</a> [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Concept-index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="I_002fO-Resources-1"></a>
<h4 class="subsection">1.2.3 I/O Resources</h4>
<dl compact="compact">
<dt><code>F</code></dt>
<dd><p>Number of major, or I/O-requiring, page faults that occurred while the
process was running. These are faults where the page has actually
migrated out of primary memory.
</p>
</dd>
<dt><code>R</code></dt>
<dd><p>Number of minor, or recoverable, page faults. These are pages that are
not valid (so they fault) but which have not yet been claimed by other
virtual pages. Thus the data in the page is still valid but the system
tables must be updated.
</p>
</dd>
<dt><code>W</code></dt>
<dd><p>Number of times the process was swapped out of main memory.
</p>
</dd>
<dt><code>c</code></dt>
<dd><p>Number of times the process was context-switched involuntarily (because
the time slice expired).
</p>
</dd>
<dt><code>w</code></dt>
<dd><p>Number of times that the program was context-switched voluntarily, for
instance while waiting for an I/O operation to complete.
</p>
</dd>
<dt><code>I</code></dt>
<dd><p>Number of file system inputs by the process.
</p>
</dd>
<dt><code>O</code></dt>
<dd><p>Number of file system outputs by the process.
</p>
</dd>
<dt><code>r</code></dt>
<dd><p>Number of socket messages received by the process.
</p>
</dd>
<dt><code>s</code></dt>
<dd><p>Number of socket messages sent by the process.
</p>
</dd>
<dt><code>k</code></dt>
<dd><p>Number of signals delivered to the process.
</p></dd>
</dl>
<hr>
<a name="Command-Info"></a>
<div class="header">
<p>
Previous: <a href="#I_002fO-Resources" accesskey="p" rel="prev">I/O Resources</a>, Up: <a href="#Format-String" accesskey="u" rel="up">Format String</a> [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Concept-index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="Command-Info-1"></a>
<h4 class="subsection">1.2.4 Command Info</h4>
<dl compact="compact">
<dt><code>C</code></dt>
<dd><p>Name and command line arguments of the command being timed.
</p>
</dd>
<dt><code>x</code></dt>
<dd><p>Exit status of the command.
</p></dd>
</dl>
<hr>
<a name="Redirecting"></a>
<div class="header">
<p>
Next: <a href="#Examples" accesskey="n" rel="next">Examples</a>, Previous: <a href="#Format-String" accesskey="p" rel="prev">Format String</a>, Up: <a href="#Resource-Measurement" accesskey="u" rel="up">Resource Measurement</a> [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Concept-index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="Redirecting-Output"></a>
<h3 class="section">1.3 Redirecting Output</h3>
<p>By default, <code>time</code> writes the resource use statistics to the
standard error stream. The options below make it write the statistics
to a file instead. Doing this can be useful if the program you’re
running writes to the standard error or you’re running <code>time</code>
noninteractively or in the background.
</p>
<dl compact="compact">
<dt><code>-o <var>file</var></code></dt>
<dt><code>--output=<var>file</var></code></dt>
<dd><p>Write the resource use statistics to <var>file</var>. By default, this
<em>overwrites</em> the file, destroying the file’s previous contents.
</p>
</dd>
<dt><code>-a</code></dt>
<dt><code>--append</code></dt>
<dd><p><em>Append</em> the resource use information to the output file instead
of overwriting it. This option is only useful with the ‘<samp>-o</samp>’ or
‘<samp>--output</samp>’ option.
</p></dd>
</dl>
<hr>
<a name="Examples"></a>
<div class="header">
<p>
Next: <a href="#Accuracy" accesskey="n" rel="next">Accuracy</a>, Previous: <a href="#Redirecting" accesskey="p" rel="prev">Redirecting</a>, Up: <a href="#Resource-Measurement" accesskey="u" rel="up">Resource Measurement</a> [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Concept-index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="Examples-1"></a>
<h3 class="section">1.4 Examples</h3>
<p>Run the command ‘<samp>wc /etc/hosts</samp>’ and show the default information:
</p>
<div class="example">
<pre class="example">eg$ time wc /etc/hosts
35 111 1134 /etc/hosts
0.00user 0.01system 0:00.04elapsed 25%CPU (0avgtext+0avgdata 0maxresident)k
1inputs+1outputs (0major+0minor)pagefaults 0swaps
</pre></div>
<p>Run the command ‘<samp>ls -Fs</samp>’ and show just the user, system, and
wall-clock time:
</p>
<div class="example">
<pre class="example">eg$ time -f "\t%E real,\t%U user,\t%S sys" ls -Fs
total 16
1 account/ 1 db/ 1 mail/ 1 run/
1 backups/ 1 emacs/ 1 msgs/ 1 rwho/
1 crash/ 1 games/ 1 preserve/ 1 spool/
1 cron/ 1 log/ 1 quotas/ 1 tmp/
0:00.03 real, 0.00 user, 0.01 sys
</pre></div>
<p>Edit the file <samp>.bashrc</samp> and have <code>time</code> append the elapsed time
and number of signals to the file <samp>log</samp>, reading the format string
from the environment variable <code>TIME</code>:
</p>
<div class="example">
<pre class="example">eg$ export TIME="\t%E,\t%k" #<span class="roman"> If using bash or ksh</span>
eg$ setenv TIME "\t%E,\t%k" #<span class="roman"> If using csh or tcsh</span>
eg$ time -a -o log emacs .bashrc
eg$ cat log
0:16.55, 726
</pre></div>
<p>Run the command ‘<samp>sleep 4</samp>’ and show all of the information about it
verbosely:
</p>
<div class="example">
<pre class="example">eg$ time -v sleep 4
Command being timed: "sleep 4"
User time (seconds): 0.00
System time (seconds): 0.05
Percent of CPU this job got: 1%
Elapsed (wall clock) time (h:mm:ss or m:ss): 0:04.26
Average shared text size (kbytes): 36
Average unshared data size (kbytes): 24
Average stack size (kbytes): 0
Average total size (kbytes): 60
Maximum resident set size (kbytes): 32
Average resident set size (kbytes): 24
Major (requiring I/O) page faults: 3
Minor (reclaiming a frame) page faults: 0
Voluntary context switches: 11
Involuntary context switches: 0
Swaps: 0
File system inputs: 3
File system outputs: 1
Socket messages sent: 0
Socket messages received: 0
Signals delivered: 1
Page size (bytes): 4096
Exit status: 0
</pre></div>
<hr>
<a name="Accuracy"></a>
<div class="header">
<p>
Next: <a href="#Invoking-time" accesskey="n" rel="next">Invoking time</a>, Previous: <a href="#Examples" accesskey="p" rel="prev">Examples</a>, Up: <a href="#Resource-Measurement" accesskey="u" rel="up">Resource Measurement</a> [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Concept-index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="Accuracy-1"></a>
<h3 class="section">1.5 Accuracy</h3>
<a name="index-error-_0028in-measurement_0029"></a>
<p>The elapsed time is not collected atomically with the execution of the
program; as a result, in bizarre circumstances (if the <code>time</code>
command gets stopped or swapped out in between when the program being
timed exits and when <code>time</code> calculates how long it took to run), it
could be much larger than the actual execution time.
</p>
<p>When the running time of a command is very nearly zero, some values
(e.g., the percentage of CPU used) may be reported as either zero (which
is wrong) or a question mark.
</p>
<p>Most information shown by <code>time</code> is derived from the <code>wait3</code>
system call. The numbers are only as good as those returned by
<code>wait3</code>. Many systems do not measure all of the resources that
<code>time</code> can report on; those resources are reported as zero. The
systems that measure most or all of the resources are based on 4.2 or
4.3BSD. Later BSD releases use different memory management code that
measures fewer resources.
</p>
<p>On systems that do not have a <code>wait3</code> call that returns status
information, the <code>times</code> system call is used instead. It provides
much less information than <code>wait3</code>, so on those systems <code>time</code>
reports most of the resources as zero.
</p>
<p>The ‘<samp>%I</samp>’ and ‘<samp>%O</samp>’ values are allegedly only “real” input
and output and do not include those supplied by caching devices. The
meaning of “real” I/O reported by ‘<samp>%I</samp>’ and ‘<samp>%O</samp>’ may be
muddled for workstations, especially diskless ones.
</p>
<hr>
<a name="Invoking-time"></a>
<div class="header">
<p>
Previous: <a href="#Accuracy" accesskey="p" rel="prev">Accuracy</a>, Up: <a href="#Resource-Measurement" accesskey="u" rel="up">Resource Measurement</a> [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Concept-index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="Running-the-time-Command"></a>
<h3 class="section">1.6 Running the <code>time</code> Command</h3>
<p>The format of the <code>time</code> command is:
</p>
<div class="example">
<pre class="example">time <span class="roman">[</span>option…<span class="roman">]</span> <var>command</var> <span class="roman">[</span><var>arg</var>…<span class="roman">]</span>
</pre></div>
<a name="index-resources"></a>
<p><code>time</code> runs the program <var>command</var>, with any given arguments
<var>arg</var>…. When <var>command</var> finishes, <code>time</code> displays
information about resources used by <var>command</var> (on the standard error
output, by default). If <var>command</var> exits with non-zero status or is
terminated by a signal, <code>time</code> displays a warning message and the
exit status or signal number.
</p>
<p>Options to <code>time</code> must appear on the command line before
<var>command</var>. Anything on the command line after <var>command</var> is
passed as arguments to <var>command</var>.
</p>
<dl compact="compact">
<dt><code>-o <var>file</var></code></dt>
<dt><code>--output=<var>file</var></code></dt>
<dd><p>Write the resource use statistics to <var>file</var>.
</p>
</dd>
<dt><code>-a</code></dt>
<dt><code>--append</code></dt>
<dd><p><em>Append</em> the resource use information to the output file instead
of overwriting it.
</p>
</dd>
<dt><code>-f <var>format</var></code></dt>
<dt><code>--format=<var>format</var></code></dt>
<dd><p>Use <var>format</var> as the format string.
</p>
</dd>
<dt><code>--help</code></dt>
<dd><p>Print a summary of the command line options to <code>time</code> and exit.
</p>
</dd>
<dt><code>-p</code></dt>
<dt><code>--portability</code></dt>
<dd><p>Use the POSIX format.
</p>
</dd>
<dt><code>-v</code></dt>
<dt><code>--verbose</code></dt>
<dd><a name="index-verbose-option"></a>
<p>Use the built-in verbose format.
</p>
</dd>
<dt><code>-V</code></dt>
<dt><code>--version</code></dt>
<dd><a name="index-version-number"></a>
<p>Print the version number of <code>time</code> and exit.
</p></dd>
</dl>
<hr>
<a name="Concept-index"></a>
<div class="header">
<p>
Previous: <a href="#Resource-Measurement" accesskey="p" rel="prev">Resource Measurement</a>, Up: <a href="#Top" accesskey="u" rel="up">Top</a> [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="#Concept-index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="Concept-index-1"></a>
<h2 class="unnumbered">Concept index</h2>
<table><tr><th valign="top">Jump to: </th><td><a class="summary-letter" href="#Concept-index_cp_letter-E"><b>E</b></a>
<a class="summary-letter" href="#Concept-index_cp_letter-F"><b>F</b></a>
<a class="summary-letter" href="#Concept-index_cp_letter-R"><b>R</b></a>
<a class="summary-letter" href="#Concept-index_cp_letter-T"><b>T</b></a>
<a class="summary-letter" href="#Concept-index_cp_letter-V"><b>V</b></a>
</td></tr></table>
<table class="index-cp" border="0">
<tr><td></td><th align="left">Index Entry</th><td> </td><th align="left"> Section</th></tr>
<tr><td colspan="4"> <hr></td></tr>
<tr><th><a name="Concept-index_cp_letter-E">E</a></th><td></td><td></td></tr>
<tr><td></td><td valign="top"><a href="#index-error-_0028in-measurement_0029">error (in measurement)</a>:</td><td> </td><td valign="top"><a href="#Accuracy">Accuracy</a></td></tr>
<tr><td colspan="4"> <hr></td></tr>
<tr><th><a name="Concept-index_cp_letter-F">F</a></th><td></td><td></td></tr>
<tr><td></td><td valign="top"><a href="#index-format">format</a>:</td><td> </td><td valign="top"><a href="#Format-String">Format String</a></td></tr>
<tr><td colspan="4"> <hr></td></tr>
<tr><th><a name="Concept-index_cp_letter-R">R</a></th><td></td><td></td></tr>
<tr><td></td><td valign="top"><a href="#index-resource-specifiers">resource specifiers</a>:</td><td> </td><td valign="top"><a href="#Resource-Measurement">Resource Measurement</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-resources">resources</a>:</td><td> </td><td valign="top"><a href="#Invoking-time">Invoking time</a></td></tr>
<tr><td colspan="4"> <hr></td></tr>
<tr><th><a name="Concept-index_cp_letter-T">T</a></th><td></td><td></td></tr>
<tr><td></td><td valign="top"><a href="#index-time-invocation">time invocation</a>:</td><td> </td><td valign="top"><a href="#Resource-Measurement">Resource Measurement</a></td></tr>
<tr><td colspan="4"> <hr></td></tr>
<tr><th><a name="Concept-index_cp_letter-V">V</a></th><td></td><td></td></tr>
<tr><td></td><td valign="top"><a href="#index-verbose-format">verbose format</a>:</td><td> </td><td valign="top"><a href="#Setting-Format">Setting Format</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-verbose-option">verbose option</a>:</td><td> </td><td valign="top"><a href="#Invoking-time">Invoking time</a></td></tr>
<tr><td></td><td valign="top"><a href="#index-version-number">version number</a>:</td><td> </td><td valign="top"><a href="#Invoking-time">Invoking time</a></td></tr>
<tr><td colspan="4"> <hr></td></tr>
</table>
<table><tr><th valign="top">Jump to: </th><td><a class="summary-letter" href="#Concept-index_cp_letter-E"><b>E</b></a>
<a class="summary-letter" href="#Concept-index_cp_letter-F"><b>F</b></a>
<a class="summary-letter" href="#Concept-index_cp_letter-R"><b>R</b></a>
<a class="summary-letter" href="#Concept-index_cp_letter-T"><b>T</b></a>
<a class="summary-letter" href="#Concept-index_cp_letter-V"><b>V</b></a>
</td></tr></table>
<hr>
</body>
</html>
AnonSec - 2021 | Recode By D7net