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12 .TH LIMIT 1 "Nov 2, 2007"
13 .SH NAME
14 limit, ulimit, unlimit \- set or get limitations on the system resources
15 available to the current shell and its descendents
16 .SH SYNOPSIS
17 .LP
18 .nf
19 \fB/usr/bin/ulimit\fR [\fB-f\fR] [\fIblocks\fR]
20 .fi
22 .SS "sh"
23 .LP
24 .nf
25 \fBulimit\fR [\fB-\fR [HS] [a | cdfnstv]]
26 .fi
28 .LP
29 .nf
30 \fBulimit\fR [\fB-\fR [HS] [c | d | f | n | s | t | v]] \fIlimit\fR
31 .fi
33 .SS "csh"
34 .LP
35 .nf
36 \fBlimit\fR [\fB-h\fR] [\fIresource\fR [\fIlimit\fR]]
37 .fi
39 .LP
40 .nf
41 \fBunlimit\fR [\fB-h\fR] [\fIresource\fR]
42 .fi
44 .SS "ksh"
45 .LP
46 .nf
47 \fBulimit\fR [\fB-HSacdfnstv\fR] [\fIlimit\fR]
48 .fi
50 .SS "ksh93"
51 .LP
52 .nf
53 \fBulimit\fR [\fB-HSacdfmnpstv\fR] [\fIlimit\fR]
54 .fi
56 .SH DESCRIPTION
57 .SS "/usr/bin/ulimit"
58 .sp
59 .LP
60 The \fBulimit\fR utility sets or reports the file-size writing limit imposed on
61 files written by the shell and its child processes (files of any size can be
62 read). Only a process with appropriate privileges can increase the limit.
63 .SS "sh"
64 .sp
65 .LP
66 The Bourne shell built-in function, \fBulimit\fR, prints or sets hard or soft
67 resource limits. These limits are described in \fBgetrlimit\fR(2).
68 .sp
69 .LP
70 If \fIlimit\fR is not present, \fBulimit\fR prints the specified limits. Any
71 number of limits can be printed at one time. The \fB-a\fR option prints all
72 limits.
73 .sp
74 .LP
75 If \fIlimit\fR is present, \fBulimit\fR sets the specified limit to\fIlimit\fR.
76 The string \fBunlimited\fR requests that the current limit, if any, be removed.
77 Any user can set a soft limit to any value less than or equal to the hard
78 limit. Any user can lower a hard limit. Only a user with appropriate privileges
79 can raise or remove a hard limit. See \fBgetrlimit\fR(2).
80 .sp
81 .LP
82 The \fB-H\fR option specifies a hard limit. The \fB-S\fR option specifies a
83 soft limit. If neither option is specified, \fBulimit\fR sets both limits and
84 prints the soft limit.
85 .sp
86 .LP
87 The following options specify the resource whose limits are to be printed or
88 set. If no option is specified, the file size limit is printed or set.
89 .sp
90 .ne 2
91 .na
92 \fB\fB-c\fR\fR
93 .ad
94 .RS 6n
95 Maximum core file size (in 512-byte blocks)
96 .RE
98 .sp
99 .ne 2
100 .na
101 \fB\fB-d\fR\fR
102 .ad
103 .RS 6n
104 Maximum size of data segment or heap (in Kbytes)
105 .RE
107 .sp
108 .ne 2
109 .na
110 \fB\fB-f\fR\fR
111 .ad
112 .RS 6n
113 Maximum file size (in 512-byte blocks)
114 .RE
116 .sp
117 .ne 2
118 .na
119 \fB\fB-n\fR\fR
120 .ad
121 .RS 6n
122 Maximum file descriptor plus 1
123 .RE
125 .sp
126 .ne 2
127 .na
128 \fB\fB-s\fR\fR
129 .ad
130 .RS 6n
131 Maximum size of stack segment (in Kbytes)
132 .RE
134 .sp
135 .ne 2
136 .na
137 \fB\fB-t\fR\fR
138 .ad
139 .RS 6n
140 Maximum CPU time (in seconds)
141 .RE
143 .sp
144 .ne 2
145 .na
146 \fB\fB-v\fR\fR
147 .ad
148 .RS 6n
149 Maximum size of virtual memory (in Kbytes)
150 .RE
152 .SS "csh"
153 .sp
154 .LP
155 The C-shell built-in function, \fBlimit\fR, limits the consumption by the
156 current process or any process it spawns, each not to exceed \fIlimit\fR on the
157 specified \fIresource\fR. The string \fBunlimited\fR requests that the current
158 limit, if any, be removed. If \fIlimit\fR is omitted, prints the current limit.
159 If \fIresource\fR is omitted, displays all limits.
160 .sp
161 .ne 2
162 .na
163 \fB\fB-h\fR\fR
164 .ad
165 .RS 6n
166 Use hard limits instead of the current limits. Hard limits impose a ceiling on
167 the values of the current limits. Only the privileged user can raise the hard
168 limits.
169 .RE
171 .sp
172 .LP
173 \fIresource\fR is one of:
174 .sp
175 .ne 2
176 .na
177 \fB\fBcputime\fR\fR
178 .ad
179 .RS 16n
180 Maximum \fBCPU\fR seconds per process.
181 .RE
183 .sp
184 .ne 2
185 .na
186 \fB\fBfilesize\fR\fR
187 .ad
188 .RS 16n
189 Largest single file allowed. Limited to the size of the filesystem (see
190 \fBdf\fR(1M)).
191 .RE
193 .sp
194 .ne 2
195 .na
196 \fB\fBdatasize\fR\fR
197 .ad
198 .RS 16n
199 The maximum size of a process's heap in kilobytes.
200 .RE
202 .sp
203 .ne 2
204 .na
205 \fB\fBstacksize\fR\fR
206 .ad
207 .RS 16n
208 Maximum stack size for the process. The default stack size is 2^64.
209 .RE
211 .sp
212 .ne 2
213 .na
214 \fB\fBcoredumpsize\fR\fR
215 .ad
216 .RS 16n
217 Maximum size of a core dump (file). This is limited to the size of the
218 filesystem.
219 .RE
221 .sp
222 .ne 2
223 .na
224 \fB\fBdescriptors\fR\fR
225 .ad
226 .RS 16n
227 Maximum number of file descriptors. Run the \fBsysdef\fR(1M) command to obtain
228 the maximum possible limits for your system. The values reported are in
229 hexadecimal, but can be translated into decimal numbers using the \fBbc\fR(1)
230 command.
231 .RE
233 .sp
234 .ne 2
235 .na
236 \fB\fBmemorysize\fR\fR
237 .ad
238 .RS 16n
239 Maximum size of virtual memory.
240 .RE
242 .sp
243 .LP
244 \fIlimit\fR is a number, with an optional scaling factor, as follows:
245 .sp
246 .ne 2
247 .na
248 \fB\fIn\fR\fBh\fR\fR
249 .ad
250 .RS 9n
251 Hours (for \fBcputime\fR).
252 .RE
254 .sp
255 .ne 2
256 .na
257 \fB\fIn\fR\fBk\fR\fR
258 .ad
259 .RS 9n
260 \fIn\fR kilobytes. This is the default for all but \fBcputime\fR.
261 .RE
263 .sp
264 .ne 2
265 .na
266 \fB\fIn\fR\fBm\fR\fR
267 .ad
268 .RS 9n
269 \fIn\fR megabytes or minutes (for \fBcputime\fR).
270 .RE
272 .sp
273 .ne 2
274 .na
275 \fB\fImm\fR\fB:\fR\fIss\fR\fR
276 .ad
277 .RS 9n
278 Minutes and seconds (for \fBcputime\fR).
279 .RE
281 .sp
282 .LP
283 \fBunlimit\fR removes a limitation on \fIresource\fR. If no \fIresource\fR is
284 specified, then all resource limitations are removed. See the description of
285 the \fBlimit\fR command for the list of resource names.
286 .sp
287 .ne 2
288 .na
289 \fB\fB-h\fR\fR
290 .ad
291 .RS 6n
292 Remove corresponding hard limits. Only the privileged user can do this.
293 .RE
295 .SS "ksh"
296 .sp
297 .LP
298 The Korn shell built-in function, \fBulimit\fR, sets or displays a resource
299 limit. The available resources limits are listed below. Many systems do not
300 contain one or more of these limits. The limit for a specified resource is set
301 when \fIlimit\fR is specified. The value of \fIlimit\fR can be a number in the
302 unit specified below with each resource, or the value \fBunlimited\fR. The
303 string \fBunlimited\fR requests that the current limit, if any, be removed. The
304 \fB-H\fR and \fB-S\fR flags specify whether the hard limit or the soft limit
305 for the specified resource is set. A hard limit cannot be increased once it is
306 set. A soft limit can be increased up to the value of the hard limit. If
307 neither the \fB-H\fR or \fB-S\fR options is specified, the limit applies to
308 both. The current resource limit is printed when \fIlimit\fR is omitted. In
309 this case, the soft limit is printed unless \fB-H\fR is specified. When more
310 than one resource is specified, then the limit name and unit is printed before
311 the value.
312 .sp
313 .ne 2
314 .na
315 \fB\fB-a\fR\fR
316 .ad
317 .RS 6n
318 Lists all of the current resource limits.
319 .RE
321 .sp
322 .ne 2
323 .na
324 \fB\fB-c\fR\fR
325 .ad
326 .RS 6n
327 The number of 512-byte blocks on the size of core dumps.
328 .RE
330 .sp
331 .ne 2
332 .na
333 \fB\fB-d\fR\fR
334 .ad
335 .RS 6n
336 The number of K-bytes on the size of the data area.
337 .RE
339 .sp
340 .ne 2
341 .na
342 \fB\fB-f\fR\fR
343 .ad
344 .RS 6n
345 The number of 512-byte blocks on files written by child processes (files of any
346 size can be read).
347 .RE
349 .sp
350 .ne 2
351 .na
352 \fB\fB-n\fR\fR
353 .ad
354 .RS 6n
355 The number of file descriptors plus 1.
356 .RE
358 .sp
359 .ne 2
360 .na
361 \fB\fB-s\fR\fR
362 .ad
363 .RS 6n
364 The number of K-bytes on the size of the stack area.
365 .RE
367 .sp
368 .ne 2
369 .na
370 \fB\fB-t\fR\fR
371 .ad
372 .RS 6n
373 The number of seconds (CPU time) to be used by each process.
374 .RE
376 .sp
377 .ne 2
378 .na
379 \fB\fB-v\fR\fR
380 .ad
381 .RS 6n
382 The number of K-bytes for virtual memory.
383 .RE
385 .sp
386 .LP
387 If no option is specified, \fB-f\fR is assumed.
388 .SS "Per-Shell Memory Parameters"
389 .sp
390 .LP
391 The \fBheapsize\fR, \fBdatasize\fR, and \fBstacksize\fR parameters are not
392 system tunables. The only controls for these are hard limits, set in a shell
393 startup file, or system-wide soft limits, which, for the current version of the
394 Solaris OS, is 2^64bytes.
395 .SS "ksh93"
396 .sp
397 .LP
398 \fBulimit\fR sets or displays resource limits. These limits apply to the
399 current process and to each child process created after the resource limit has
400 been set. If \fIlimit\fR is specified, the resource limit is set, otherwise,
401 its current value is displayed on standard output.
402 .sp
403 .LP
404 Increasing the limit for a resource usually requires special privileges. Some
405 systems allow you to lower resource limits and later increase them. These are
406 called soft limits. Once a hard limit is set the resource cannot be increased.
407 .sp
408 .LP
409 Different systems allow you to specify different resources and some restrict
410 how much you can raise the limit of the resource.
411 .sp
412 .LP
413 The value of \fIlimit\fR depends on the unit of the resource listed for each
414 resource. In addition, \fIlimit\fR can be "unlimited" to indicate no limit for
415 that resource.
416 .sp
417 .LP
418 If you do not specify \fB-H\fR or \fB-S\fR, \fB-S\fR is used for listing and
419 both \fB-S\fR and \fB-H\fR are used for setting resources.
420 .sp
421 .LP
422 If you do not specify any resource, the default is \fB-f.\fR
423 .sp
424 .LP
425 The following options are available for \fBulimit\fR in \fBksh93\fR:
426 .sp
427 .ne 2
428 .na
429 \fB\fB-a\fR\fR
430 .ad
431 .RS 13n
432 Displays all current resource limits.
433 .RE
435 .sp
436 .ne 2
437 .na
438 \fB\fB-b\fR\fR
439 .ad
440 .br
441 .na
442 \fB\fB--sbsize\fR\fR
443 .ad
444 .RS 13n
445 Specifies the socket buffer size in bytes.
446 .RE
448 .sp
449 .ne 2
450 .na
451 \fB\fB-c\fR\fR
452 .ad
453 .br
454 .na
455 \fB\fB--core\fR\fR
456 .ad
457 .RS 13n
458 Specifies the core file size in blocks.
459 .RE
461 .sp
462 .ne 2
463 .na
464 \fB\fB-d\fR\fR
465 .ad
466 .br
467 .na
468 \fB\fB--data\fR\fR
469 .ad
470 .RS 13n
471 Specifies the data size in kbytes.
472 .RE
474 .sp
475 .ne 2
476 .na
477 \fB\fB-f\fR\fR
478 .ad
479 .br
480 .na
481 \fB\fB--fsize\fR\fR
482 .ad
483 .RS 13n
484 Specifies the file size in blocks.
485 .RE
487 .sp
488 .ne 2
489 .na
490 \fB\fB-H\fR\fR
491 .ad
492 .RS 13n
493 Displays or sets a hard limit.
494 .RE
496 .sp
497 .ne 2
498 .na
499 \fB\fB-L\fR\fR
500 .ad
501 .br
502 .na
503 \fB\fB--locks\fR\fR
504 .ad
505 .RS 13n
506 Specifies the number of file locks.
507 .RE
509 .sp
510 .ne 2
511 .na
512 \fB\fB-l\fR\fR
513 .ad
514 .br
515 .na
516 \fB\fB--memlock\fR\fR
517 .ad
518 .RS 13n
519 Specifies the locked address space in Kbytes.
520 .RE
522 .sp
523 .ne 2
524 .na
525 \fB\fB-M\fR\fR
526 .ad
527 .br
528 .na
529 \fB\fB--as\fR\fR
530 .ad
531 .RS 13n
532 Specifies the address space limit in Kbytes.
533 .RE
535 .sp
536 .ne 2
537 .na
538 \fB\fB-n\fR\fR
539 .ad
540 .br
541 .na
542 \fB\fB--nofile\fR\fR
543 .ad
544 .RS 13n
545 Specifies the number of open files.
546 .RE
548 .sp
549 .ne 2
550 .na
551 \fB\fB-p\fR\fR
552 .ad
553 .br
554 .na
555 \fB\fB--pipe\fR\fR
556 .ad
557 .RS 13n
558 Specifies the pipe buffer size in bytes.
559 .RE
561 .sp
562 .ne 2
563 .na
564 \fB\fB-m\fR\fR
565 .ad
566 .br
567 .na
568 \fB\fB--rss\fR\fR
569 .ad
570 .RS 13n
571 Specifies the resident set size in Kbytes
572 .RE
574 .sp
575 .ne 2
576 .na
577 \fB\fB-S\fR\fR
578 .ad
579 .RS 13n
580 Displays or sets a soft limit.
581 .RE
583 .sp
584 .ne 2
585 .na
586 \fB\fB-s\fR\fR
587 .ad
588 .br
589 .na
590 \fB\fB--stack\fR\fR
591 .ad
592 .RS 13n
593 Specifies the stack size in Kbytes.
594 .RE
596 .sp
597 .ne 2
598 .na
599 \fB\fB-T\fR\fR
600 .ad
601 .br
602 .na
603 \fB\fB--threads\fR\fR
604 .ad
605 .RS 13n
606 Specifies the number of threads.
607 .RE
609 .sp
610 .ne 2
611 .na
612 \fB\fB-t\fR\fR
613 .ad
614 .br
615 .na
616 \fB\fB--cpu\fR\fR
617 .ad
618 .RS 13n
619 Specifies the CPU time in seconds.
620 .RE
622 .sp
623 .ne 2
624 .na
625 \fB\fB-u\fR\fR
626 .ad
627 .br
628 .na
629 \fB\fB--nproc\fR\fR
630 .ad
631 .RS 13n
632 Specifies the number of processes.
633 .RE
635 .sp
636 .ne 2
637 .na
638 \fB\fB-v\fR\fR
639 .ad
640 .br
641 .na
642 \fB\fB--vmem\fR\fR
643 .ad
644 .RS 13n
645 Specifies the process size in Kbytes.
646 .RE
648 .SH OPTIONS
649 .sp
650 .LP
651 The following option is supported by \fB/usr/bin/ulimit\fR:
652 .sp
653 .ne 2
654 .na
655 \fB\fB-f\fR\fR
656 .ad
657 .RS 6n
658 Sets (or reports, if no \fIblocks\fR operand is present), the file size limit
659 in blocks. The \fB-f\fR option is also the default case.
660 .RE
662 .SH OPERANDS
663 .sp
664 .LP
665 The following operand is supported by \fB/usr/bin/ulimit\fR:
666 .sp
667 .ne 2
668 .na
669 \fB\fIblocks\fR\fR
670 .ad
671 .RS 10n
672 The number of 512-byte blocks to use as the new file size limit.
673 .RE
675 .SH EXAMPLES
676 .SS "/usr/bin/ulimit"
677 .LP
678 \fBExample 1 \fRLimiting the Stack Size
679 .sp
680 .LP
681 The following example limits the stack size to 512 kilobytes:
683 .sp
684 .in +2
685 .nf
686 example% \fBulimit -s 512\fR
687 example% \fBulimit -a\fR
688 time(seconds) unlimited
689 file(blocks) 100
690 data(kbytes) 523256
691 stack(kbytes) 512
692 coredump(blocks) 200
693 nofiles(descriptors) 64
694 memory(kbytes) unlimited
695 .fi
696 .in -2
697 .sp
699 .SS "sh/ksh"
700 .LP
701 \fBExample 2 \fRLimiting the Number of File Descriptors
702 .sp
703 .LP
704 The following command limits the number of file descriptors to 12:
706 .sp
707 .in +2
708 .nf
709 example$ \fBulimit -n 12\fR
710 example$ \fBulimit -a\fR
711 time(seconds) unlimited
712 file(blocks) 41943
713 data(kbytes) 523256
714 stack(kbytes) 8192
715 coredump(blocks) 200
716 nofiles(descriptors) 12
717 vmemory(kbytes) unlimited
718 .fi
719 .in -2
720 .sp
722 .SS "csh"
723 .LP
724 \fBExample 3 \fRLimiting the Core Dump File Size
725 .sp
726 .LP
727 The following command limits the size of a core dump file size to 0 kilobytes:
729 .sp
730 .in +2
731 .nf
732 example% \fBlimit coredumpsize 0\fR
733 example% \fBlimit\fR
734 cputime unlimited
735 filesize unlimited
736 datasize 523256 kbytes
737 stacksize 8192 kbytes
738 coredumpsize 0 kbytes
739 descriptors 64
740 memorysize unlimited
741 .fi
742 .in -2
743 .sp
745 .LP
746 \fBExample 4 \fRRemoving the limitation for core file size
747 .sp
748 .LP
749 The following command removes the above limitation for the core file size:
751 .sp
752 .in +2
753 .nf
754 example% \fBunlimit coredumpsize\fR
755 example% \fBlimit\fR
756 cputime unlimited
757 filesize unlimited
758 datasize 523256 kbytes
759 stacksize 8192 kbytes
760 coredumpsize unlimited
761 descriptors 64
762 memorysize unlimited
763 .fi
764 .in -2
765 .sp
767 .SH ENVIRONMENT VARIABLES
768 .sp
769 .LP
770 See \fBenviron\fR(5) for descriptions of the following environment variables
771 that affect the execution of \fBulimit\fR: \fBLANG\fR, \fBLC_ALL\fR,
772 \fBLC_CTYPE\fR, \fBLC_MESSAGES\fR, and \fBNLSPATH\fR.
773 .SH EXIT STATUS
774 .sp
775 .LP
776 The following exit values are returned by \fBulimit\fR:
777 .sp
778 .ne 2
779 .na
780 \fB\fB0\fR\fR
781 .ad
782 .RS 6n
783 Successful completion.
784 .RE
786 .sp
787 .ne 2
788 .na
789 \fB\fB>0\fR\fR
790 .ad
791 .RS 6n
792 A request for a higher limit was rejected or an error occurred.
793 .RE
795 .SH ATTRIBUTES
796 .sp
797 .LP
798 See \fBattributes\fR(5) for descriptions of the following attributes:
799 .SS "/usr/bin/ulimit, csh, ksh, sh"
800 .sp
802 .sp
803 .TS
804 box;
805 c | c
806 l | l .
807 ATTRIBUTE TYPE ATTRIBUTE VALUE
808 _
809 Interface Stability Committed
810 _
811 Standard See \fBstandards\fR(5).
812 .TE
814 .SS "ksh93"
815 .sp
817 .sp
818 .TS
819 box;
820 c | c
821 l | l .
822 ATTRIBUTE TYPE ATTRIBUTE VALUE
823 _
824 Interface Stability Uncommitted
825 .TE
827 .SH SEE ALSO
828 .sp
829 .LP
830 \fBbc\fR(1), \fBcsh\fR(1), \fBksh\fR(1), \fBksh93\fR(1), \fBsh\fR(1),
831 \fBdf\fR(1M), \fBsu\fR(1M), \fBswap\fR(1M), \fBsysdef\fR(1M),
832 \fBgetrlimit\fR(2), \fBattributes\fR(5), \fBenviron\fR(5), \fBstandards\fR(5)