projects / unix-history / blame
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| 59c7bf5e KM |
1 | .\" Copyright (c) 1980 Regents of the University of California. |
| 2 | .\" All rights reserved. The Berkeley software License Agreement | |
| 3 | .\" specifies the terms and conditions for redistribution. | |
| 4 | .\" | |
| 5 | .\" @(#)vlimit.3 4.1 (Berkeley) %G% | |
| 6 | .\" | |
| 7 | .TH VLIMIT 2V | |
| 8 | .UC 4 | |
| 9 | .SH NAME | |
| 10 | vlimit \- control maximum system resource consumption | |
| 11 | .SH SYNOPSIS | |
| 12 | .B "#include <sys/vlimit.h>" | |
| 13 | .PP | |
| 14 | .B vlimit(resource, value) | |
| 15 | .SH DESCRIPTION | |
| 16 | Limits the consumption by the current process and each process | |
| 17 | it creates to not individually exceed | |
| 18 | .I value | |
| 19 | on the specified | |
| 20 | .I resource. | |
| 21 | If | |
| 22 | .I value | |
| 23 | is specified as \-1, then the current limit is returned and the | |
| 24 | limit is unchanged. | |
| 25 | The resources which are currently controllable are: | |
| 26 | .TP 15 | |
| 27 | .B LIM_NORAISE | |
| 28 | A pseudo-limit; if set non-zero then the limits may not be raised. | |
| 29 | Only the super-user may remove the \fInoraise\fR restriction. | |
| 30 | .TP 15 | |
| 31 | .B LIM_CPU | |
| 32 | the maximum | |
| 33 | number of cpu-seconds to be used by each process | |
| 34 | .TP 15 | |
| 35 | .B LIM_FSIZE | |
| 36 | the largest single file which can be created | |
| 37 | .TP 15 | |
| 38 | .B LIM_DATA | |
| 39 | the maximum growth of the data+stack region via | |
| 40 | .IR sbrk (2) | |
| 41 | beyond the end of the program text | |
| 42 | .TP 15 | |
| 43 | .B LIM_STACK | |
| 44 | the maximum | |
| 45 | size of the automatically-extended stack region | |
| 46 | .TP 15 | |
| 47 | .B LIM_CORE | |
| 48 | the size of the largest core dump that will be created. | |
| 49 | .TP 15 | |
| 50 | .B LIM_MAXRSS | |
| 51 | a soft limit for the amount of physical memory (in bytes) to be given | |
| 52 | to the program. If memory is tight, the system will prefer to take memory | |
| 53 | from processes which are exceeding their declared LIM_MAXRSS. | |
| 54 | .PP | |
| 55 | Because this information is stored in the per-process information | |
| 56 | this system call must be executed directly by the shell if it | |
| 57 | is to affect all future processes created by the shell; | |
| 58 | .I limit | |
| 59 | is thus a built-in command to | |
| 60 | .IR csh (1). | |
| 61 | .PP | |
| 62 | The system refuses to extend the data or stack space when the limits | |
| 63 | would be exceeded in the normal way; a | |
| 64 | .I break | |
| 65 | call fails if the data space limit is reached, or the process is | |
| 66 | killed when the stack limit is reached (since the stack cannot be | |
| 67 | extended, there is no way to send a signal!). | |
| 68 | .PP | |
| 69 | A file i/o operation which would create a file which is too large | |
| 70 | will cause a signal SIGXFSZ to be generated, this normally terminates | |
| 71 | the process, but may be caught. | |
| 72 | When the cpu time limit is exceeded, a signal SIGXCPU is sent to the | |
| 73 | offending process; to allow it time to process the signal it is | |
| 74 | given 5 seconds grace by raising the cpu time limit. | |
| 75 | .SH SEE ALSO | |
| 76 | csh(1) | |
| 77 | .SH BUGS | |
| 78 | If LIM_NORAISE is set, then no grace should be given when the cpu | |
| 79 | time limit is exceeded. | |
| 80 | .PP | |
| 81 | There should be | |
| 82 | .I limit | |
| 83 | and | |
| 84 | .I unlimit | |
| 85 | commands in | |
| 86 | .IR sh (1) | |
| 87 | as well as in | |
| 88 | .IR csh. | |
| 89 | .PP | |
| 90 | This call is peculiar to this version of UNIX. | |
| 91 | The options and specifications of this system call and even the call itself | |
| 92 | are subject to change. It may be extended or replaced by other | |
| 93 | facilities in future versions of the system. |