1GETRLIMIT(2) System Calls Manual GETRLIMIT(2)
2
6 getrlimit, setrlimit - control maximum system resource consumption
7
9 #include <sys/time.h>
10 #include <sys/resource.h>
11 getrlimit(resource, rlp)
13 int resource;
14 struct rlimit *rlp;
15 setrlimit(resource, rlp)
17 int resource;
18 struct rlimit *rlp;
19
21 Limits on the consumption of system resources by the current process
22 and each process it creates may be obtained with the getrlimit call,
23 and set with the setrlimit call.
24 The resource parameter is one of the following:
26 RLIMIT_CPU the maximum amount of cpu time (in seconds) to be used
28 by each process.
29 RLIMIT_FSIZE the largest size, in bytes, of any single file that
31 may be created.
32 RLIMIT_DATA the maximum size, in bytes, of the data segment for a
34 process; this defines how far a program may extend its
35 break with the sbrk(2) system call.
36 RLIMIT_STACK the maximum size, in bytes, of the stack segment for a
38 process; this defines how far a program's stack seg‐
39 ment may be extended. Stack extension is performed
40 automatically by the system.
41 RLIMIT_CORE the largest size, in bytes, of a core file that may be
43 created.
44 RLIMIT_RSS the maximum size, in bytes, to which a process's resi‐
46 dent set size may grow. This imposes a limit on the
47 amount of physical memory to be given to a process; if
48 memory is tight, the system will prefer to take memory
49 from processes that are exceeding their declared resi‐
50 dent set size.
51 A resource limit is specified as a soft limit and a hard limit. When a
53 soft limit is exceeded a process may receive a signal (for example, if
54 the cpu time is exceeded), but it will be allowed to continue execution
55 until it reaches the hard limit (or modifies its resource limit). The
56 rlimit structure is used to specify the hard and soft limits on a
57 resource,
58 struct rlimit {
60 int rlim_cur; /* current (soft) limit */
61 int rlim_max; /* hard limit */
62 };
63 Only the super-user may raise the maximum limits. Other users may only
65 alter rlim_cur within the range from 0 to rlim_max or (irreversibly)
66 lower rlim_max.
67 An “infinite” value for a limit is defined as RLIM_INFINITY
69 (0x7fffffff).
70 Because this information is stored in the per-process information, this
72 system call must be executed directly by the shell if it is to affect
73 all future processes created by the shell; limit is thus a built-in
74 command to csh(1).
75 The system refuses to extend the data or stack space when the limits
77 would be exceeded in the normal way: a break call fails if the data
78 space limit is reached. When the stack limit is reached, the process
79 receives a segmentation fault (SIGSEGV); if this signal is not caught
80 by a handler using the signal stack, this signal will kill the process.
81 A file I/O operation that would create a file that is too large will
83 cause a signal SIGXFSZ to be generated; this normally terminates the
84 process, but may be caught. When the soft cpu time limit is exceeded,
85 a signal SIGXCPU is sent to the offending process.
86
88 A 0 return value indicates that the call succeeded, changing or return‐
89 ing the resource limit. A return value of -1 indicates that an error
90 occurred, and an error code is stored in the global location errno.
91
93 The possible errors are:
94 [EFAULT] The address specified for rlp is invalid.
96 [EPERM] The limit specified to setrlimit would have
98 raised the maximum limit value, and the caller is not
99 the super-user.
100
102 csh(1), quota(2), sigvec(2), sigstack(2)
103
105 There should be limit and unlimit commands in sh(1) as well as in csh.
1064th Berkeley Distribution May 13, 1986 GETRLIMIT(2)