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| <!-- Creator : groff version 1.19.2 --> | |
| <!-- CreationDate: Fri Sep 14 10:51:19 2018 --> | |
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| <p valign="top">GETRLIMIT(2) BSD System Calls Manual | |
| GETRLIMIT(2)</p> | |
| <p style="margin-top: 1em" valign="top"><b>NAME</b></p> | |
| <p style="margin-left:8%;"><b>getrlimit</b>, | |
| <b>setrlimit</b> — control maximum system resource | |
| consumption</p> | |
| <p style="margin-top: 1em" valign="top"><b>SYNOPSIS</b></p> | |
| <p style="margin-left:8%;"><b>#include | |
| <sys/resource.h></b></p> | |
| <p style="margin-left:8%; margin-top: 1em"><i>int</i></p> | |
| <p valign="top"><b>getrlimit</b>(<i>int resource</i>, | |
| <i>struct rlimit *rlp</i>);</p> | |
| <p style="margin-left:8%; margin-top: 1em"><i>int</i></p> | |
| <p valign="top"><b>setrlimit</b>(<i>int resource</i>, | |
| <i>const struct rlimit *rlp</i>);</p> | |
| <p style="margin-top: 1em" valign="top"><b>DESCRIPTION</b></p> | |
| <p style="margin-left:8%;">Limits on the consumption of | |
| system resources by the current process and each process it | |
| creates may be obtained with the <b>getrlimit</b>() call, | |
| and set with the <b>setrlimit</b>() call.</p> | |
| <p style="margin-left:8%; margin-top: 1em">The | |
| <i>resource</i> parameter is one of the following:</p> | |
| <p style="margin-top: 1em" valign="top">RLIMIT_CORE</p> | |
| <p style="margin-left:32%; margin-top: 1em">The largest | |
| size (in bytes) core file that may be created.</p> | |
| <p style="margin-top: 1em" valign="top">RLIMIT_CPU</p> | |
| <p style="margin-left:32%; margin-top: 1em">The maximum | |
| amount of cpu time (in seconds) to be used by each | |
| process.</p> | |
| <p style="margin-top: 1em" valign="top">RLIMIT_DATA</p> | |
| <p style="margin-left:32%; margin-top: 1em">The maximum | |
| size (in bytes) of the data segment for a process; this | |
| defines how far a program may extend its break with the | |
| sbrk(2) system call.</p> | |
| <p style="margin-top: 1em" valign="top">RLIMIT_FSIZE</p> | |
| <p style="margin-left:32%; margin-top: 1em">The largest | |
| size (in bytes) file that may be created.</p> | |
| <p style="margin-top: 1em" valign="top">RLIMIT_MEMLOCK</p> | |
| <p style="margin-left:32%; margin-top: 1em">The maximum | |
| size (in bytes) which a process may lock into memory using | |
| the mlock(2) function.</p> | |
| <p style="margin-top: 1em" valign="top">RLIMIT_NOFILE</p> | |
| <p style="margin-left:32%; margin-top: 1em">The maximum | |
| number of open files for this process.</p> | |
| <p style="margin-top: 1em" valign="top">RLIMIT_NPROC</p> | |
| <p style="margin-left:32%; margin-top: 1em">The maximum | |
| number of simultaneous processes for this user id.</p> | |
| <p style="margin-top: 1em" valign="top">RLIMIT_RSS</p> | |
| <p style="margin-left:32%; margin-top: 1em">The maximum | |
| size (in bytes) to which a process’s resident set size | |
| may grow. This imposes a limit on the amount of physical | |
| memory to be given to a process; if memory is tight, the | |
| system will prefer to take memory from processes that are | |
| exceeding their declared resident set size.</p> | |
| <p style="margin-top: 1em" valign="top">RLIMIT_STACK</p> | |
| <p style="margin-left:32%; margin-top: 1em">The maximum | |
| size (in bytes) of the stack segment for a process; this | |
| defines how far a program’s stack segment may be | |
| extended. Stack extension is performed automatically by the | |
| system.</p> | |
| <p style="margin-left:8%; margin-top: 1em">A resource limit | |
| is specified as a soft limit and a hard limit. When a soft | |
| limit is exceeded a process may receive a signal (for | |
| example, if the cpu time or file size is exceeded), but it | |
| will be allowed to continue execution until it reaches the | |
| hard limit (or modifies its resource limit). The | |
| <i>rlimit</i> structure is used to specify the hard and soft | |
| limits on a resource,</p> | |
| <p style="margin-left:17%; margin-top: 1em">struct rlimit | |
| {</p> | |
| <table width="100%" border=0 rules="none" frame="void" | |
| cellspacing="0" cellpadding="0"> | |
| <tr valign="top" align="left"> | |
| <td width="29%"></td> | |
| <td width="13%"> | |
| <p valign="top">rlim_t</p></td> | |
| <td width="12%"> | |
| <p valign="top">rlim_cur;</p></td> | |
| <td width="12%"></td> | |
| <td width="12%"> | |
| <p valign="top">/* current (soft) limit */</p></td> | |
| <td width="22%"> | |
| </td> | |
| <tr valign="top" align="left"> | |
| <td width="29%"></td> | |
| <td width="13%"> | |
| <p valign="top">rlim_t</p></td> | |
| <td width="12%"> | |
| <p valign="top">rlim_max;</p></td> | |
| <td width="12%"></td> | |
| <td width="12%"> | |
| <p valign="top">/* hard limit */</p></td> | |
| <td width="22%"> | |
| </td> | |
| </table> | |
| <p style="margin-left:17%;">};</p> | |
| <p style="margin-left:8%; margin-top: 1em">Only the | |
| super-user may raise the maximum limits. Other users may | |
| only alter <i>rlim_cur</i> within the range from 0 to | |
| <i>rlim_max</i> or (irreversibly) lower <i>rlim_max</i>.</p> | |
| <p style="margin-left:8%; margin-top: 1em">Because this | |
| information is stored in the per-process information, this | |
| system call must be executed directly by the shell if it is | |
| to affect all future processes created by the shell; | |
| <b>limit</b> is thus a built-in command to csh(1) and | |
| <b>ulimit</b> is the sh(1) equivalent.</p> | |
| <p style="margin-left:8%; margin-top: 1em">The system | |
| refuses to extend the data or stack space when the limits | |
| would be exceeded in the normal way: a break call fails if | |
| the data space limit is reached. When the stack limit is | |
| reached, the process receives a segmentation fault | |
| (SIGSEGV); if this signal is not caught by a handler using | |
| the signal stack, this signal will kill the process.</p> | |
| <p style="margin-left:8%; margin-top: 1em">A file I/O | |
| operation that would create a file larger that the | |
| process’ soft limit will cause the write to fail and a | |
| signal SIGXFSZ to be generated; this normally terminates the | |
| process, but may be caught. When the soft cpu time limit is | |
| exceeded, a signal SIGXCPU is sent to the offending | |
| process.</p> | |
| <p style="margin-top: 1em" valign="top"><b>RETURN | |
| VALUES</b></p> | |
| <p style="margin-left:8%;">A 0 return value indicates that | |
| the call succeeded, changing or returning the resource | |
| limit. A return value of -1 indicates that an error | |
| occurred, and an error code is stored in the global location | |
| <i>errno</i>.</p> | |
| <p style="margin-top: 1em" valign="top"><b>ERRORS</b></p> | |
| <p style="margin-left:8%;">The <b>getrlimit</b>() and | |
| <b>setrlimit</b>() system calls will fail if:</p> | |
| <p style="margin-top: 1em" valign="top">[EFAULT]</p> | |
| <p style="margin-left:37%; margin-top: 1em">The address | |
| specified for <i>rlp</i> is invalid.</p> | |
| <p style="margin-top: 1em" valign="top">[EINVAL]</p> | |
| <p style="margin-left:37%; margin-top: 1em"><i>resource</i> | |
| is invalid.</p> | |
| <p style="margin-left:8%; margin-top: 1em">The | |
| <b>setrlimit</b>() call will fail if:</p> | |
| <p style="margin-top: 1em" valign="top">[EINVAL]</p> | |
| <p style="margin-left:37%; margin-top: 1em">The specified | |
| limit is invalid (e.g., RLIM_INFINITY or lower than | |
| rlim_cur).</p> | |
| <p style="margin-top: 1em" valign="top">[EPERM]</p> | |
| <p style="margin-left:37%; margin-top: 1em">The limit | |
| specified would have raised the maximum limit value and the | |
| caller is not the super-user.</p> | |
| <p style="margin-top: 1em" valign="top"><b>LEGACY | |
| SYNOPSIS</b></p> | |
| <p style="margin-left:8%;"><b>#include <sys/types.h> | |
| <br> | |
| #include <sys/time.h> <br> | |
| #include <sys/resource.h></b></p> | |
| <p style="margin-left:8%; margin-top: 1em">The include | |
| files <<i>sys/types.h</i>> and | |
| <<i>sys/time.h</i>> are necessary.</p> | |
| <p style="margin-top: 1em" valign="top"><b>COMPATIBILITY</b></p> | |
| <p style="margin-left:8%;"><b>setrlimit</b>() now returns | |
| with <i>errno</i> set to EINVAL in places that historically | |
| succeeded. It no longer accepts "rlim_cur = | |
| RLIM_INFINITY" for RLIM_NOFILE. Use "rlim_cur = | |
| min(OPEN_MAX, rlim_max)".</p> | |
| <p style="margin-top: 1em" valign="top"><b>SEE ALSO</b></p> | |
| <p style="margin-left:8%;">csh(1), sh(1), quota(2), | |
| sigaction(2), sigaltstack(2), sysctl(3), compat(5)</p> | |
| <p style="margin-top: 1em" valign="top"><b>HISTORY</b></p> | |
| <p style="margin-left:8%;">The <b>getrlimit</b>() function | |
| call appeared in 4.2BSD.</p> | |
| <p style="margin-left:8%; margin-top: 1em">4th Berkeley | |
| Distribution June 4, 1993 4th Berkeley | |
| Distribution</p> | |
| <hr> | |
| </body> | |
| </html> |
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