236 lines
6.0 KiB
HTML
236 lines
6.0 KiB
HTML
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<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
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<html>
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<head>
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<meta http-equiv="content-type" content="text/html; charset=utf-8">
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<meta name="Copyright" content="Copyright (c) 2006 by IBM Corporation">
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<title>ulimit()--Get and set process limits</title>
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<!-- All rights reserved. Licensed Materials Property of IBM -->
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<!-- US Government Users Restricted Rights -->
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<!-- Use, duplication or disclosure restricted by -->
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<!-- GSA ADP Schedule Contract with IBM Corp. -->
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<!-- Begin Header Records ========================================== -->
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<!-- Edited by Kersten Jan 02 -->
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<link rel="stylesheet" type="text/css" href="../rzahg/ic.css">
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</head>
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<body>
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<a name="Top_Of_Page"></a>
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<!-- Java sync-link -->
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<script type="text/javascript" language="Javascript" src="../rzahg/synch.js">
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</script>
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<h2>ulimit()--Get and set process limits</h2>
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<div class="box" style="width: 50%;">
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<br>
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Syntax
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<pre>
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#include <ulimit.h>
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long int ulimit(int <em>cmd</em>, ...);
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</pre>
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Service Program Name: QP0WSRV1<br>
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<!-- iddvc RMBR -->
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<br>
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Default Public Authority: *USE<br>
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<!-- iddvc RMBR -->
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<br>
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Threadsafe: Yes<br>
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<!-- iddvc RMBR -->
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<br>
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</div>
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<p>The <strong>ulimit()</strong> function provides a way to get and set process
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resource limits. A resource limit is a way for the operating system to enforce
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a limit on a variety of resources used by a process. A resource limit has a
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current or soft limit and a maximum or hard limit.</p>
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<p>The <strong>ulimit()</strong> function is provided for compatibility with
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older applications. The <a href="getrlim.htm">getrlimit()</a> and <a href=
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"setrlim.htm">setrlimit()</a> functions should be used for working with
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resource limits.</p>
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<p>A soft limit can be changed to any value that is less than or equal to the
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hard limit. The hard limit can be changed to any value that is greater than or
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equal to the soft limit. Only a process with appropriate authorities can
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increase a hard limit.</p>
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<p>The <strong>ulimit()</strong> function supports the following <em>cmd</em>
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values:</p>
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<table cellpadding="5">
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<!-- cols="15 85" -->
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<tr>
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<td align="left" valign="top"><em>UL_GETFSIZE (0)</em></td>
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<td align="left" valign="top">Return the current or soft limit for the file
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size resource limit. The returned limit is in 512-byte blocks. The return value
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is the integer part of the file size resource limit divided by 512.</td>
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</tr>
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<tr>
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<td align="left" valign="top" nowrap><em>UL_SETFSIZE (1)</em></td>
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<td align="left" valign="top">Set the current or soft limit and the maximum or
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hard limit for the file size resource limit. The second argument is taken as a
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long int that represents the limit in 512-byte blocks. The specified value is
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multiplied by 512 to set the resource limit. If the result overflows an rlim_t,
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<strong>ulimit()</strong> returns -1 and sets <em>errno</em> to EINVAL. The new
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file size resource limit is returned.</td>
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</tr>
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</table>
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<br>
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<br>
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<h3>Parameters</h3>
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<dl>
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<dt><strong><em>cmd</em></strong></dt>
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<dd>(Input)
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<p>The command to be performed.</p>
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</dd>
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<dt><strong>...</strong></dt>
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<dd>(Input)
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<p>When the <em>cmd</em> is UL_SETFSIZE, a long int that represents the limit
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in 512-byte blocks.</p>
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</dd>
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</dl>
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<br>
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<h3>Authorities and Locks</h3>
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<p>The current user profile must have *JOBCTL special authority to increase the
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hard limit.</p>
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<br>
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<h3>Return Value</h3>
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<table cellpadding="5">
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<!-- cols="10 90" -->
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<tr>
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<td align="left" valign="top"><strong>value</strong></td>
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<td align="left" valign="top"><strong>ulimit()</strong> was successful. The
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value is the requested limit.</td>
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</tr>
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<tr>
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<td align="left" valign="top"><strong>-1</strong></td>
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<td align="left" valign="top"><strong>ulimit()</strong> was not successful. The
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<em>errno</em> variable is set to indicate the error.</td>
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</tr>
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</table>
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<br>
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<br>
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<h3>Error Conditions</h3>
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<p>If <strong>ulimit()</strong> is not successful, <em>errno</em> usually
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indicates one of the following errors. Under some conditions, <em>errno</em>
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could indicate an error other than those listed here.</p>
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<dl>
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<dt><em>[EINVAL]</em></dt>
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<dd><p>An invalid parameter was found. </p>
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<p>An invalid <em>cmd</em> was specified.</p>
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</dd>
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<dt><em>[EPERM]</em></dt>
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<dd><p>Permission denied.</p>
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<p>An attempt was made to increase the hard limit and the current user profile
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does not have *JOBCTL special authority.</p>
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</dd>
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</dl>
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<br>
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<br>
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<h3>Related Information</h3>
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<ul>
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<li>The <<strong>ulimit.h</strong>> file (see <a href="unix13.htm">Header
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Files for UNIX-Type Functions</a>)<br>
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<br>
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</li>
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<li><a href="getrlim.htm">getrlimit()</a>--Get resource limit<br>
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<br>
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</li>
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<li><a href="setrlim.htm">setrlimit()</a>--Set resource limit<br>
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<br>
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</li>
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</ul>
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<br>
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<h3>Example</h3>
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<p>See <a href="../apiref/aboutapis.htm#codedisclaimer">Code disclaimer information</a>
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for information pertaining to code examples.</p>
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<pre>
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#include <ulimit.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <errno.h>
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int main (int argc, char *argv[])
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{
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long int value;
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long int limit;
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/* Set the file size resource limit. */
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limit = 65535;
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errno = 0;
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value = ulimit(UL_SETFSIZE, limit);
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if ((value == -1) && (errno != 0)) {
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printf("ulimit() failed with errno=%d\n", errno);
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exit(1);
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}
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printf("The limit is set to %ld\n", value);
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/* Get the file size resource limit. */
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value = ulimit(UL_GETFSIZE);
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if ((value == -1) && (errno != 0)) {
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printf("ulimit() failed with errno=%d\n", errno);
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exit(1);
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}
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printf("The limit is %ld\n", value);
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exit(0);
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}
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</pre>
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<strong>Example Output:</strong>
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<pre>
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The limit is set to 65535
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The limit is 65535
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</pre>
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<br>
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<br>
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<hr>
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Introduced: V5R2
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<hr>
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<center>
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<table cellpadding="2" cellspacing="2">
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<tr align="center">
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<td valign="middle" align="center"><a href="#Top_Of_Page">Top</a> | <a href=
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"unix.htm">UNIX-Type APIs</a> | <a href="aplist.htm">APIs by category</a></td>
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</tr>
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</table>
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</center>
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</body>
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</html>
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