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GETRLIMIT(2) | System Calls Manual | GETRLIMIT(2) |
NAME¶
getrlimit
,
setrlimit
—
control maximum system resource consumption
LIBRARY¶
Standard C Library (libc, -lc)SYNOPSIS¶
#include
<sys/types.h>
#include
<sys/time.h>
#include
<sys/resource.h>
int
getrlimit
(int
resource, struct
rlimit *rlp);
int
setrlimit
(int
resource, const
struct rlimit *rlp);
DESCRIPTION¶
Limits on the consumption of system resources by the current process and each process it creates may be obtained with thegetrlimit
() system call, and set with the
setrlimit
() system call.
The resource argument is one of the following:
RLIMIT_AS
- The maximum amount (in bytes) of virtual memory the process is allowed to map.
RLIMIT_CORE
- The largest size (in bytes) core(5) file that may be created.
RLIMIT_CPU
- The maximum amount of cpu time (in seconds) to be used by each process.
RLIMIT_DATA
- 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) function.
RLIMIT_FSIZE
- The largest size (in bytes) file that may be created.
RLIMIT_MEMLOCK
- The maximum size (in bytes) which a process may lock into memory using the mlock(2) system call.
RLIMIT_NOFILE
- The maximum number of open files for this process.
RLIMIT_NPROC
- The maximum number of simultaneous processes for this user id.
RLIMIT_RSS
- 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.
RLIMIT_SBSIZE
- The maximum size (in bytes) of socket buffer usage for this user. This limits the amount of network memory, and hence the amount of mbufs, that this user may hold at any time.
RLIMIT_STACK
- 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.
RLIMIT_SWAP
- The maximum size (in bytes) of the swap space that may be reserved or used by all of this user id's processes. This limit is enforced only if bit 1 of the vm.overcommit sysctl is set. Please see tuning(7) for a complete description of this sysctl.
RLIMIT_NPTS
- The maximum number of pseudo-terminals created by this user id.
struct rlimit { rlim_t rlim_cur; /* current (soft) limit */ rlim_t rlim_max; /* maximum value for rlim_cur */ };
RLIM_INFINITY
.
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; limit
is
thus a built-in command to csh(1).
The system refuses to extend the data or stack space when the limits would be
exceeded in the normal way: a brk(2) function
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.
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.
RETURN VALUES¶
Upon successful completion, the value 0 is returned; otherwise the value -1 is returned and the global variable errno is set to indicate the error.ERRORS¶
Thegetrlimit
() and
setrlimit
() system calls will fail if:
- [
EFAULT
] - The address specified for rlp is invalid.
- [
EPERM
] - The limit specified to
setrlimit
() would have raised the maximum limit value, and the caller is not the super-user.
SEE ALSO¶
csh(1), quota(1), quotactl(2), sigaltstack(2), sigaction(2), sysctl(3), ulimit(3)HISTORY¶
Thegetrlimit
() system call appeared in
4.2BSD.August 20, 2008 | Debian |