prctl(2) System Calls Manual prctl(2)

prctl - operations on a process or thread

Standard C library (libc, -lc)

#include <linux/prctl.h>  /* Definition of PR_* constants */
#include <sys/prctl.h>
int prctl(int op, ...);

prctl() manipulates various aspects of the behavior of the calling thread or process.

prctl() is called with a first argument describing what to do, and further arguments with a significance depending on the first one. The first argument can be:

On success, a nonnegative value is returned. On error, -1 is returned, and errno is set to indicate the error.

The value of op is not recognized, or not supported on this system.
An unused argument is nonzero.

IRIX has a prctl() system call (also introduced in Linux 2.1.44 as irix_prctl on the MIPS architecture), with prototype


ptrdiff_t prctl(int op, int arg2, int arg3);

and operations to get the maximum number of processes per user, get the maximum number of processors the calling process can use, find out whether a specified process is currently blocked, get or set the maximum stack size, and so on.

Linux.

Linux 2.1.57, glibc 2.0.6

The prototype of the libc wrapper uses a variadic argument list. This makes it necessary to pass the arguments with the right width. When passing numeric constants, such as 0, use a suffix: 0L.

Careless use of some prctl() operations can confuse the user-space run-time environment, so these operations should be used with care.

signal(2), PR_CAP_AMBIENT(2const), PR_CAPBSET_READ(2const), PR_CAPBSET_DROP(2const), PR_SET_CHILD_SUBREAPER(2const), PR_GET_CHILD_SUBREAPER(2const), PR_SET_DUMPABLE(2const), PR_GET_DUMPABLE(2const), PR_SET_ENDIAN(2const), PR_GET_ENDIAN(2const), PR_SET_FP_MODE(2const), PR_GET_FP_MODE(2const), PR_SET_FPEMU(2const), PR_GET_FPEMU(2const), PR_SET_FPEXC(2const), PR_GET_FPEXC(2const), PR_SET_IO_FLUSHER(2const), PR_GET_IO_FLUSHER(2const), PR_SET_KEEPCAPS(2const), PR_GET_KEEPCAPS(2const), PR_MCE_KILL(2const), PR_MCE_KILL_GET(2const), PR_SET_MM(2const), PR_SET_VMA(2const), PR_MPX_ENABLE_MANAGEMENT(2const), PR_MPX_DISABLE_MANAGEMENT(2const), PR_SET_NAME(2const), PR_GET_NAME(2const), PR_SET_NO_NEW_PRIVS(2const), PR_GET_NO_NEW_PRIVS(2const), PR_PAC_RESET_KEYS(2const), PR_SET_PDEATHSIG(2const), PR_GET_PDEATHSIG(2const), PR_SET_PTRACER(2const), PR_SET_SECCOMP(2const), PR_GET_SECCOMP(2const), PR_SET_SECUREBITS(2const), PR_GET_SECUREBITS(2const), PR_SET_SPECULATION_CTRL(2const), PR_GET_SPECULATION_CTRL(2const), PR_SVE_SET_VL(2const), PR_SVE_GET_VL(2const), PR_SET_SYSCALL_USER_DISPATCH(2const), PR_SET_TAGGED_ADDR_CTRL(2const), PR_GET_TAGGED_ADDR_CTRL(2const), PR_TASK_PERF_EVENTS_DISABLE(2const), PR_TASK_PERF_EVENTS_ENABLE(2const), PR_SET_THP_DISABLE(2const), PR_GET_THP_DISABLE(2const), PR_GET_TID_ADDRESS(2const), PR_SET_TIMERSLACK(2const), PR_GET_TIMERSLACK(2const), PR_SET_TIMING(2const), PR_GET_TIMING(2const), PR_SET_TSC(2const), PR_GET_TSC(2const), PR_SET_UNALIGN(2const), PR_GET_UNALIGN(2const), PR_GET_AUXV(2const), PR_SET_MDWE(2const), PR_GET_MDWE(2const), PR_RISCV_SET_ICACHE_FLUSH_CTX(2const), PR_FUTEX_HASH(2const), core(5)

2025-06-11 Linux man-pages (unreleased)

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