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<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 3.2 Final//EN"><html><head><!-- Copyright 1997 The Open Group, All Rights Reserved --><title>getrlimit</title></head><body bgcolor=white><center><font size=2>The Single UNIX ® Specification, Version 2<br>Copyright © 1997 The Open Group</font></center><hr size=2 noshade><h4><a name = "tag_000_005_713"> </a>NAME</h4><blockquote>getrlimit, setrlimit - control maximum resource consumption</blockquote><h4><a name = "tag_000_005_714"> </a>SYNOPSIS</h4><blockquote><pre><code>#include <<a href="sysresource.h.html">sys/resource.h</a>>int getrlimit(int <i>resource</i>, struct rlimit *<i>rlp</i>);int setrlimit(int <i>resource</i>, const struct rlimit *<i>rlp</i>);</code></pre></blockquote><h4><a name = "tag_000_005_715"> </a>DESCRIPTION</h4><blockquote>Limits on the consumption of a variety of resources by the calling processmay be obtained with<i>getrlimit()</i>and set with<i>setrlimit()</i>.<p>Each call to either<i>getrlimit()</i>or<i>setrlimit()</i>identifies a specific resource to be operated upon as well as a resourcelimit.A resource limit is represented by an<b>rlimit</b>structure. The<b>rlim_cur</b>member specifies the current or soft limit and the<b>rlim_max</b>member specifies the maximum or hard limit. Soft limits may be changed bya process to any value that is less than or equal to the hard limit. Aprocess may (irreversibly) lower its hard limit to any value that is greaterthan or equal to the soft limit. Only a process with appropriate privilegescan raise a hard limit. Both hard and soft limits can be changed in a singlecall to<i>setrlimit()</i>subject to the constraints described above.<p>The value RLIM_INFINITY, defined in<i><a href="sysresource.h.html"><sys/resource.h></a></i>,is considered to be larger than any other limit value. If a call to<i>getrlimit()</i>returns RLIM_INFINITY for a resource, it means the implementation does notenforce limits on that resource.Specifying RLIM_INFINITY as any resource limit value on a successful call to<i>setrlimit()</i>inhibits enforcement of that resource limit.<p>The following resources are defined:<dl compact><dt>RLIMIT_CORE<dd>This is the maximum size of a core file in bytes that may be created by aprocess. A limit of 0 will prevent the creation of a core file. If thislimit is exceeded, the writing of a core file will terminate at this size.<dt>RLIMIT_CPU<dd>This is the maximum amount of CPU time in seconds used by a process.If this limit is exceeded, SIGXCPU is generated for the process. If theprocess is catching or ignoring SIGXCPU, or all threads belonging tothat process are blocking SIGXCPU, the behaviour is unspecified.<dt>RLIMIT_DATA<dd>This is the maximum size of a process' data segment in bytes.If this limit is exceeded, the<i><a href="brk.html">brk()</a></i>,<i><a href="malloc.html">malloc()</a></i>and<i><a href="sbrk.html">sbrk()</a></i>functions will fail with <i>errno</i> set to [ENOMEM].<dt>RLIMIT_FSIZE<dd>This is the maximum size of a file in bytes that may be created by a process.If a write or truncate operation would cause this limit to be exceeded,SIGXFSZ is generated for the thread. If the thread is blocking, orthe process is catching or ignoring SIGXFSZ, continued attempts toincrease the size of a file from end-of-file to beyond the limitwill fail with <i>errno</i> set to [EFBIG].<dt>RLIMIT_NOFILE<dd>This is a number one greater than the maximum value that the system mayassign to a newly-created descriptor. If this limit is exceeded,functions that allocate new file descriptors may failwith errno set to [EMFILE]. This limit constrains the number offile descriptors that a process may allocate.<dt>RLIMIT_STACK<dd>This is the maximum size of a process' stack in bytes. The implementationwill not automatically grow the stack beyond this limit. If this limit isexceeded, SIGSEGV is generated for the thread. If the thread is blockingSIGSEGV, or the process is ignoring or catching SIGSEGV and has not madearrangements to use an alternate stack, the disposition of SIGSEGV will be setto SIG_DFL before it is generated.<dt>RLIMIT_AS<dd>This is the maximum size of a process' total available memory, inbytes. If this limit is exceeded, the<i><a href="brk.html">brk()</a></i>,<i><a href="malloc.html">malloc()</a></i>,<i><a href="mmap.html">mmap()</a></i>and<i><a href="sbrk.html">sbrk()</a></i>functions will fail with <i>errno</i> set to [ENOMEM]. In addition, theautomatic stack growth will fail with the effects outlined above.</dl><p>When using the <i>getrlimit()</i>function, if a resource limit can berepresented correctly in an object of type <b>rlim_t</b>then its representation is returned; otherwise if the value of the resourcelimit is equal to that of the corresponding saved hard limit, the valuereturned is RLIM_SAVED_MAX; otherwise the value returned isRLIM_SAVED_CUR. <p>When using the <i>setrlimit()</i>function, if the requested new limit isRLIM_INFINITY the new limit will be "no limit"; otherwise if therequested new limit is RLIM_SAVED_MAX, the new limit will be thecorresponding saved hard limit; otherwise if the requested new limitis RLIM_SAVED_CUR, the new limit will be the corresponding saved softlimit; otherwise the new limit will be the requested value. Inaddition, if the corresponding saved limit can be representedcorrectly in an object of type <b>rlim_t</b>then it will be overwritten withthe new limit. <p>The result of setting a limit to RLIM_SAVED_MAX or RLIM_SAVED_CUR isunspecified unless a previous call to <i>getrlimit()</i>returned that valueas the soft or hard limit for the corresponding resource limit. <p>The determination of whether a limit can be correctly represented inan object of type <b>rlim_t</b>is implementation-dependent. For example,some implementations permit a limit whose value is greater thanRLIM_INFINITY and others do not. <p>The <i>exec</i> family of functions also cause resource limits to be saved. </blockquote><h4><a name = "tag_000_005_716"> </a>RETURN VALUE</h4><blockquote>Upon successful completion,<i>getrlimit()</i>and<i>setrlimit()</i>return 0. Otherwise, these functions return -1 and set<i>errno</i> to indicate the error.</blockquote><h4><a name = "tag_000_005_717"> </a>ERRORS</h4><blockquote>The<i>getrlimit()</i>and<i>setrlimit()</i>functions will fail if:<dl compact><dt>[EINVAL]<dd>An invalid <i>resource</i> was specified; or in a<i>setrlimit()</i>call, the new <b>rlim_cur</b> exceeds the new <b>rlim_max</b>.<dt>[EPERM]<dd>The limit specified to<i>setrlimit()</i>would have raised the maximum limit value, and the calling process does nothave appropriate privileges.</dl><p>The<i>setrlimit()</i>function may fail if:<dl compact><dt>[EINVAL]<dd>The limit specified cannot be lowered because current usage is already higherthan the limit.</dl></blockquote><h4><a name = "tag_000_005_718"> </a>EXAMPLES</h4><blockquote>None.</blockquote><h4><a name = "tag_000_005_719"> </a>APPLICATION USAGE</h4><blockquote>If a process attempts to set the hard limit or soft limit forRLIMIT_NOFILE to less than the value of _POSIX_OPEN_MAX from<i><a href="limits.h.html"><limits.h></a></i>,unexpected behaviour may occur.</blockquote><h4><a name = "tag_000_005_720"> </a>FUTURE DIRECTIONS</h4><blockquote>None.</blockquote><h4><a name = "tag_000_005_721"> </a>SEE ALSO</h4><blockquote><i><a href="brk.html">brk()</a></i>,<i><a href="exec.html">exec</a></i>,<i><a href="fork.html">fork()</a></i>,<i><a href="malloc.html">malloc()</a></i>,<i><a href="open.html">open()</a></i>,<i><a href="sbrk.html">sbrk()</a></i>,<i><a href="sigaltstack.html">sigaltstack()</a></i>,<i><a href="sysconf.html">sysconf()</a></i>,<i><a href="ulimit.html">ulimit()</a></i>,<i><a href="stropts.h.html"><stropts.h></a></i>,<i><a href="sysresource.h.html"><sys/resource.h></a></i>.</blockquote><hr size=2 noshade><center><font size=2>UNIX ® is a registered Trademark of The Open Group.<br>Copyright © 1997 The Open Group<br> [ <a href="../index.html">Main Index</a> | <a href="../xshix.html">XSH</a> | <a href="../xcuix.html">XCU</a> | <a href="../xbdix.html">XBD</a> | <a href="../cursesix.html">XCURSES</a> | <a href="../xnsix.html">XNS</a> ]</font></center><hr size=2 noshade></body></html>⌨️ 快捷键说明
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