prctl(2) - Linux manual page (original) (raw)

prctl(2) System Calls Manual prctl(2)

NAME top

   prctl - operations on a process or thread

LIBRARY top

   Standard C library (_libc_, _-lc_)

SYNOPSIS top

   **#include <linux/prctl.h>** /* Definition of **PR_*** constants */
   **#include <sys/prctl.h>**

   **int prctl(int** _op_**, ...);**

DESCRIPTION top

   **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**

RETURN VALUE top

   On success, a nonnegative value is returned.  On error, -1 is
   returned, and _[errno](../man3/errno.3.html)_ is set to indicate the error.

ERRORS top

   **EINVAL** The value of _op_ is not recognized, or not supported on this
          system.

   **EINVAL** An unused argument is nonzero.

VERSIONS top

   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.

STANDARDS top

   Linux.

HISTORY top

   Linux 2.1.57, glibc 2.0.6

CAVEATS top

   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.

SEE ALSO top

   [signal(2)](../man2/signal.2.html), [PR_CAP_AMBIENT(2const)](../man2/PR%5FCAP%5FAMBIENT.2const.html), [PR_CAPBSET_READ(2const)](../man2/PR%5FCAPBSET%5FREAD.2const.html),
   [PR_CAPBSET_DROP(2const)](../man2/PR%5FCAPBSET%5FDROP.2const.html), [PR_SET_CHILD_SUBREAPER(2const)](../man2/PR%5FSET%5FCHILD%5FSUBREAPER.2const.html),
   [PR_GET_CHILD_SUBREAPER(2const)](../man2/PR%5FGET%5FCHILD%5FSUBREAPER.2const.html), [PR_SET_DUMPABLE(2const)](../man2/PR%5FSET%5FDUMPABLE.2const.html),
   [PR_GET_DUMPABLE(2const)](../man2/PR%5FGET%5FDUMPABLE.2const.html), [PR_SET_ENDIAN(2const)](../man2/PR%5FSET%5FENDIAN.2const.html),
   [PR_GET_ENDIAN(2const)](../man2/PR%5FGET%5FENDIAN.2const.html), [PR_SET_FP_MODE(2const)](../man2/PR%5FSET%5FFP%5FMODE.2const.html),
   [PR_GET_FP_MODE(2const)](../man2/PR%5FGET%5FFP%5FMODE.2const.html), [PR_SET_FPEMU(2const)](../man2/PR%5FSET%5FFPEMU.2const.html),
   [PR_GET_FPEMU(2const)](../man2/PR%5FGET%5FFPEMU.2const.html), [PR_SET_FPEXC(2const)](../man2/PR%5FSET%5FFPEXC.2const.html), [PR_GET_FPEXC(2const)](../man2/PR%5FGET%5FFPEXC.2const.html),
   [PR_SET_IO_FLUSHER(2const)](../man2/PR%5FSET%5FIO%5FFLUSHER.2const.html), [PR_GET_IO_FLUSHER(2const)](../man2/PR%5FGET%5FIO%5FFLUSHER.2const.html),
   [PR_SET_KEEPCAPS(2const)](../man2/PR%5FSET%5FKEEPCAPS.2const.html), [PR_GET_KEEPCAPS(2const)](../man2/PR%5FGET%5FKEEPCAPS.2const.html),
   [PR_MCE_KILL(2const)](../man2/PR%5FMCE%5FKILL.2const.html), [PR_MCE_KILL_GET(2const)](../man2/PR%5FMCE%5FKILL%5FGET.2const.html), [PR_SET_MM(2const)](../man2/PR%5FSET%5FMM.2const.html),
   [PR_SET_VMA(2const)](../man2/PR%5FSET%5FVMA.2const.html), [PR_MPX_ENABLE_MANAGEMENT(2const)](../man2/PR%5FMPX%5FENABLE%5FMANAGEMENT.2const.html),
   [PR_MPX_DISABLE_MANAGEMENT(2const)](../man2/PR%5FMPX%5FDISABLE%5FMANAGEMENT.2const.html), [PR_SET_NAME(2const)](../man2/PR%5FSET%5FNAME.2const.html),
   [PR_GET_NAME(2const)](../man2/PR%5FGET%5FNAME.2const.html), [PR_SET_NO_NEW_PRIVS(2const)](../man2/PR%5FSET%5FNO%5FNEW%5FPRIVS.2const.html),
   [PR_GET_NO_NEW_PRIVS(2const)](../man2/PR%5FGET%5FNO%5FNEW%5FPRIVS.2const.html), [PR_PAC_RESET_KEYS(2const)](../man2/PR%5FPAC%5FRESET%5FKEYS.2const.html),
   [PR_SET_PDEATHSIG(2const)](../man2/PR%5FSET%5FPDEATHSIG.2const.html), [PR_GET_PDEATHSIG(2const)](../man2/PR%5FGET%5FPDEATHSIG.2const.html),
   [PR_SET_PTRACER(2const)](../man2/PR%5FSET%5FPTRACER.2const.html), [PR_SET_SECCOMP(2const)](../man2/PR%5FSET%5FSECCOMP.2const.html),
   [PR_GET_SECCOMP(2const)](../man2/PR%5FGET%5FSECCOMP.2const.html), [PR_SET_SECUREBITS(2const)](../man2/PR%5FSET%5FSECUREBITS.2const.html),
   [PR_GET_SECUREBITS(2const)](../man2/PR%5FGET%5FSECUREBITS.2const.html), [PR_SET_SPECULATION_CTRL(2const)](../man2/PR%5FSET%5FSPECULATION%5FCTRL.2const.html),
   [PR_GET_SPECULATION_CTRL(2const)](../man2/PR%5FGET%5FSPECULATION%5FCTRL.2const.html), [PR_SVE_SET_VL(2const)](../man2/PR%5FSVE%5FSET%5FVL.2const.html),
   [PR_SVE_GET_VL(2const)](../man2/PR%5FSVE%5FGET%5FVL.2const.html), [PR_SET_SYSCALL_USER_DISPATCH(2const)](../man2/PR%5FSET%5FSYSCALL%5FUSER%5FDISPATCH.2const.html),
   [PR_SET_TAGGED_ADDR_CTRL(2const)](../man2/PR%5FSET%5FTAGGED%5FADDR%5FCTRL.2const.html), [PR_GET_TAGGED_ADDR_CTRL(2const)](../man2/PR%5FGET%5FTAGGED%5FADDR%5FCTRL.2const.html),
   [PR_TASK_PERF_EVENTS_DISABLE(2const)](../man2/PR%5FTASK%5FPERF%5FEVENTS%5FDISABLE.2const.html),
   [PR_TASK_PERF_EVENTS_ENABLE(2const)](../man2/PR%5FTASK%5FPERF%5FEVENTS%5FENABLE.2const.html), [PR_SET_THP_DISABLE(2const)](../man2/PR%5FSET%5FTHP%5FDISABLE.2const.html),
   [PR_GET_THP_DISABLE(2const)](../man2/PR%5FGET%5FTHP%5FDISABLE.2const.html), [PR_GET_TID_ADDRESS(2const)](../man2/PR%5FGET%5FTID%5FADDRESS.2const.html),
   [PR_SET_TIMERSLACK(2const)](../man2/PR%5FSET%5FTIMERSLACK.2const.html), [PR_GET_TIMERSLACK(2const)](../man2/PR%5FGET%5FTIMERSLACK.2const.html),
   [PR_SET_TIMING(2const)](../man2/PR%5FSET%5FTIMING.2const.html), [PR_GET_TIMING(2const)](../man2/PR%5FGET%5FTIMING.2const.html), [PR_SET_TSC(2const)](../man2/PR%5FSET%5FTSC.2const.html),
   [PR_GET_TSC(2const)](../man2/PR%5FGET%5FTSC.2const.html), [PR_SET_UNALIGN(2const)](../man2/PR%5FSET%5FUNALIGN.2const.html),
   [PR_GET_UNALIGN(2const)](../man2/PR%5FGET%5FUNALIGN.2const.html), [PR_GET_AUXV(2const)](../man2/PR%5FGET%5FAUXV.2const.html), [PR_SET_MDWE(2const)](../man2/PR%5FSET%5FMDWE.2const.html),
   [PR_GET_MDWE(2const)](../man2/PR%5FGET%5FMDWE.2const.html), [PR_RISCV_SET_ICACHE_FLUSH_CTX(2const)](../man2/PR%5FRISCV%5FSET%5FICACHE%5FFLUSH%5FCTX.2const.html),
   [core(5)](../man5/core.5.html)

COLOPHON top

   This page is part of the _man-pages_ (Linux kernel and C library
   user-space interface documentation) project.  Information about
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   2025-02-02.  If you discover any rendering problems in this HTML
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   to-date source for the page, or you have corrections or
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   part of the original manual page), send a mail to
   man-pages@man7.org

Linux man-pages 6.10 2024-07-23 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_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)