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HTML rendering created 2025-09-06 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. |
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NAME | LIBRARY | SYNOPSIS | DESCRIPTION | RETURN VALUE | ERRORS | VERSIONS | STANDARDS | HISTORY | CAVEATS | SEE ALSO | COLOPHON |
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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:
PR_CAP_AMBIENT
PR_CAPBSET_READ
PR_CAPBSET_DROP
PR_SET_CHILD_SUBREAPER
PR_GET_CHILD_SUBREAPER
PR_SET_DUMPABLE
PR_GET_DUMPABLE
PR_SET_ENDIAN
PR_GET_ENDIAN
PR_SET_FP_MODE
PR_GET_FP_MODE
PR_SET_FPEMU
PR_GET_FPEMU
PR_SET_FPEXC
PR_GET_FPEXC
PR_SET_IO_FLUSHER
PR_GET_IO_FLUSHER
PR_SET_KEEPCAPS
PR_GET_KEEPCAPS
PR_MCE_KILL
PR_MCE_KILL_GET
PR_SET_MM
PR_SET_VMA
PR_MPX_ENABLE_MANAGEMENT
PR_MPX_DISABLE_MANAGEMENT
PR_SET_NAME
PR_GET_NAME
PR_SET_NO_NEW_PRIVS
PR_GET_NO_NEW_PRIVS
PR_PAC_RESET_KEYS
PR_SET_PDEATHSIG
PR_GET_PDEATHSIG
PR_SET_PTRACER
PR_SET_SECCOMP
PR_GET_SECCOMP
PR_SET_SECUREBITS
PR_GET_SECUREBITS
PR_GET_SPECULATION_CTRL
PR_SET_SPECULATION_CTRL
PR_SVE_SET_VL
PR_SVE_GET_VL
PR_SET_SYSCALL_USER_DISPATCH
PR_SET_TAGGED_ADDR_CTRL
PR_GET_TAGGED_ADDR_CTRL
PR_TASK_PERF_EVENTS_DISABLE
PR_TASK_PERF_EVENTS_ENABLE
PR_SET_THP_DISABLE
PR_GET_THP_DISABLE
PR_GET_TID_ADDRESS
PR_SET_TIMERSLACK
PR_GET_TIMERSLACK
PR_SET_TIMING
PR_GET_TIMING
PR_SET_TSC
PR_GET_TSC
PR_SET_UNALIGN
PR_GET_UNALIGN
PR_GET_AUXV
PR_SET_MDWE
PR_GET_MDWE
PR_RISCV_SET_ICACHE_FLUSH_CTX
PR_FUTEX_HASH
On success, a nonnegative value is returned. On error, -1 is
returned, and errno is set to indicate the error.
EINVAL The value of op is not recognized, or not supported on this
system.
EINVAL 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)
This page is part of the man-pages (Linux kernel and C library
user-space interface documentation) project. Information about
the project can be found at
⟨https://www.kernel.org/doc/man-pages/⟩. If you have a bug report
for this manual page, see
⟨https://git.kernel.org/pub/scm/docs/man-pages/man-pages.git/tree/CONTRIBUTING⟩.
This page was obtained from the tarball man-pages-6.15.tar.gz
fetched from
⟨https://mirrors.edge.kernel.org/pub/linux/docs/man-pages/⟩ on
2025-08-11. If you discover any rendering problems in this HTML
version of the page, or you believe there is a better or more up-
to-date source for the page, or you have corrections or
improvements to the information in this COLOPHON (which is not
part of the original manual page), send a mail to
[email protected]
Linux man-pages 6.15 2025-06-11 prctl(2)
Pages that refer to this page: capsh(1), setpriv(1), systemd-nspawn(1), arch_prctl(2), execve(2), _exit(2), fork(2), getpid(2), madvise(2), perf_event_open(2), PR_CAP_AMBIENT(2const), PR_CAP_AMBIENT_CLEAR_ALL(2const), PR_CAP_AMBIENT_IS_SET(2const), PR_CAP_AMBIENT_LOWER(2const), PR_CAP_AMBIENT_RAISE(2const), PR_CAPBSET_DROP(2const), PR_CAPBSET_READ(2const), PR_FUTEX_HASH(2const), PR_GET_AUXV(2const), PR_GET_CHILD_SUBREAPER(2const), PR_GET_DUMPABLE(2const), PR_GET_ENDIAN(2const), PR_GET_FPEMU(2const), PR_GET_FPEXC(2const), PR_GET_FP_MODE(2const), PR_GET_IO_FLUSHER(2const), PR_GET_MDWE(2const), PR_GET_NO_NEW_PRIVS(2const), PR_GET_SECCOMP(2const), PR_GET_SECUREBITS(2const), PR_GET_SPECULATION_CTRL(2const), PR_GET_TAGGED_ADDR_CTRL(2const), PR_GET_THP_DISABLE(2const), PR_GET_TID_ADDRESS(2const), PR_GET_TIMING(2const), PR_GET_TSC(2const), PR_GET_UNALIGN(2const), PR_MCE_KILL(2const), PR_MCE_KILL_CLEAR(2const), PR_MCE_KILL_GET(2const), PR_MCE_KILL_SET(2const), PR_MPX_ENABLE_MANAGEMENT(2const), PR_PAC_RESET_KEYS(2const), PR_RISCV_SET_ICACHE_FLUSH_CTX(2const), PR_SET_CHILD_SUBREAPER(2const), PR_SET_DUMPABLE(2const), PR_SET_ENDIAN(2const), PR_SET_FPEMU(2const), PR_SET_FPEXC(2const), PR_SET_FP_MODE(2const), PR_SET_IO_FLUSHER(2const), PR_SET_KEEPCAPS(2const), PR_SET_MDWE(2const), PR_SET_MM(2const), PR_SET_MM_ARG_START(2const), PR_SET_MM_AUXV(2const), PR_SET_MM_BRK(2const), PR_SET_MM_EXE_FILE(2const), PR_SET_MM_MAP(2const), PR_SET_MM_START_BRK(2const), PR_SET_MM_START_CODE(2const), PR_SET_MM_START_DATA(2const), PR_SET_MM_START_STACK(2const), PR_SET_NAME(2const), PR_SET_NO_NEW_PRIVS(2const), PR_SET_PDEATHSIG(2const), PR_SET_PTRACER(2const), PR_SET_SECCOMP(2const), PR_SET_SECUREBITS(2const), PR_SET_SPECULATION_CTRL(2const), PR_SET_SYSCALL_USER_DISPATCH(2const), PR_SET_TAGGED_ADDR_CTRL(2const), PR_SET_THP_DISABLE(2const), PR_SET_TIMERSLACK(2const), PR_SET_TIMING(2const), PR_SET_TSC(2const), PR_SET_UNALIGN(2const), PR_SET_VMA(2const), PR_SVE_GET_VL(2const), PR_SVE_SET_VL(2const), PR_TASK_PERF_EVENTS_DISABLE(2const), ptrace(2), seccomp(2), seccomp_unotify(2), syscalls(2), wait(2), capng_change_id(3), capng_lock(3), exit(3), lttng-ust(3), pthread_setname_np(3), sd_event_add_time(3), core(5), proc_pid(5), proc_pid_cmdline(5), proc_pid_comm(5), proc_pid_environ(5), proc_pid_maps(5), proc_pid_seccomp(5), proc_pid_status(5), proc_pid_timerslack_ns(5), proc_sys_fs(5), proc_sys_vm(5), systemd.exec(5), systemd-system.conf(5), systemd.timer(5), capabilities(7), credentials(7), environ(7), pid_namespaces(7), time(7), user_namespaces(7), mount.fuse3(8), systemd-coredump(8)
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HTML rendering created 2025-09-06 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. |
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