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GETRLIMIT

NAME

SYNOPSIS

int getrlimit(int resource, struct rlimit *rlim);
int setrlimit(int resource, const struct rlimit *rlim);  

DESCRIPTION

struct rlimit {
    rlim_t rlim_cur;  /* Soft limit */
    rlim_t rlim_max;  /* Hard limit (ceiling for rlim_cur) */
};

The value RLIM_INFINITY denotes no limit on a resource (both in the structure returned by getrlimit() and in the structure passed to setrlimit()).

resource must be one of:

RLIMIT_AS

The maximum size of the process's virtual memory (address space) in bytes. This limit affects calls to brk(2), mmap(2) and mremap(2), which fail with the error ENOMEM upon exceeding this limit. Also automatic stack expansion will fail (and generate a SIGSEGV that kills the process if no alternate stack has been made available via sigaltstack(2)). Since the value is a long, on machines with a 32-bit long either this limit is at most 2 GiB, or this resource is unlimited.

RLIMIT_CORE

Maximum size of core file. When 0 no core dump files are created. When nonzero, larger dumps are truncated to this size.

RLIMIT_CPU

CPU time limit in seconds. When the process reaches the soft limit, it is sent a SIGXCPU signal. The default action for this signal is to terminate the process. However, the signal can be caught, and the handler can return control to the main program. If the process continues to consume CPU time, it will be sent SIGXCPU once per second until the hard limit is reached, at which time it is sent SIGKILL. (This latter point describes Linux 2.2 through 2.6 behaviour. Implementations vary in how they treat processes which continue to consume CPU time after reaching the soft limit. Portable applications that need to catch this signal should perform an orderly termination upon first receipt of SIGXCPU.)

RLIMIT_DATA

The maximum size of the process's data segment (initialized data, uninitialized data, and heap). This limit affects calls to brk() and sbrk(), which fail with the error ENOMEM upon encountering the soft limit of this resource.

RLIMIT_FSIZE

The maximum size of files that the process may create. Attempts to extend a file beyond this limit result in delivery of a SIGXFSZ signal. By default, this signal terminates a process, but a process can catch this signal instead, in which case the relevant system call (e.g., write(), truncate()) fails with the error EFBIG.

RLIMIT_LOCKS

A limit on the combined number of flock() locks and fcntl() leases that this process may establish. (Early Linux 2.4 only.)

RLIMIT_MEMLOCK

The maximum number of bytes of memory that may be locked into RAM. In effect this limit is rounded down to the nearest multiple of the system page size. This limit affects mlock(2) and mlockall(2) and the mmap(2) MAP_LOCKED operation. Since Linux 2.6.9 it also affects the shmctl(2) SHM_LOCK operation, where it sets a maximum on the total bytes in shared memory segments (see shmget(2)) that may be locked by the real user ID of the calling process. The shmctl(2) SHM_LOCK locks are accounted for separately from the per-process memory locks established by mlock(2), mlockall(2), and mmap(2) MAP_LOCKED; a process can lock bytes up to this limit in each of these two categories. In Linux kernels before 2.6.9, this limit controlled the amount of memory that could be locked by a privileged process. Since Linux 2.6.9, no limits are placed on the amount of memory that a privileged process may lock, and this limit instead governs the amount of memory that an unprivileged process may lock.

RLIMIT_NOFILE

Specifies a value one greater than the maximum file descriptor number that can be opened by this process. Attempts (open(), pipe(), dup(), etc.) to exceed this limit yield the error EMFILE.

RLIMIT_NPROC

The maximum number of processes that can be created for the real user ID of the calling process. Upon encountering this limit, fork() fails with the error EAGAIN.

RLIMIT_RSS

Specifies the limit (in pages) of the process's resident set (the number of virtual pages resident in RAM). This limit only has effect in Linux 2.4 onwatrds, and there only affects calls to madvise() specifying MADVISE_WILLNEED.

RLIMIT_SIGPENDING

Specifies the limit on the number of signals that may be queued for the real user ID of the calling process. Both standard and real-time signals are counted for the purpose of checking this limit. However, the limit is only enforced for sigqueue(2); it is always possible to use kill(2) to queue one instance of any of the signals that are not already queued to the process. (Since Linux 2.6.8.)

RLIMIT_STACK

The maximum size of the process stack, in bytes. Upon reaching this limit, a SIGSEGV signal is generated. To handle this signal, a process must employ an alternate signal stack (sigaltstack(2)).

RLIMIT_OFILE is the BSD name for RLIMIT_NOFILE.  

RETURN VALUE

ERRORS

EFAULT

rlim points outside the accessible address space.

EINVAL

resource is not valid.

EPERM

An unprivileged process tried to use setrlimit() to increase a soft or hard limit above the current hard limit; the CAP_SYS_RESOURCE capability is required to do this. Or, the process tried to use setrlimit() to increase the soft or hard RLIMIT_NOFILE limit above the current kernel maximum (NR_OPEN).

BUGS

CONFORMING TO

SEE ALSO

Index

NAME

SYNOPSIS

DESCRIPTION

RETURN VALUE

ERRORS

BUGS

CONFORMING TO

SEE ALSO

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