mirror of https://github.com/mkerrisk/man-pages
239 lines
8.2 KiB
Groff
239 lines
8.2 KiB
Groff
.\" Hey Emacs! This file is -*- nroff -*- source.
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.\"
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.\" Copyright (C) 1998 Andries Brouwer (aeb@cwi.nl)
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.\" and Copyright (C) 2002 Michael Kerrisk <mtk.manpages@gmail.com>
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.\" and Copyright Guillem Jover <guillem@hadrons.org>
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.\"
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.\" Permission is granted to make and distribute verbatim copies of this
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.\" manual provided the copyright notice and this permission notice are
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.\" preserved on all copies.
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.\"
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.\" Permission is granted to copy and distribute modified versions of this
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.\" manual under the conditions for verbatim copying, provided that the
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.\" entire resulting derived work is distributed under the terms of a
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.\" permission notice identical to this one.
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.\"
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.\" Since the Linux kernel and libraries are constantly changing, this
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.\" manual page may be incorrect or out-of-date. The author(s) assume no
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.\" responsibility for errors or omissions, or for damages resulting from
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.\" the use of the information contained herein. The author(s) may not
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.\" have taken the same level of care in the production of this manual,
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.\" which is licensed free of charge, as they might when working
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.\" professionally.
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.\"
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.\" Formatted or processed versions of this manual, if unaccompanied by
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.\" the source, must acknowledge the copyright and authors of this work.
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.\"
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.\" Modified Thu Nov 11 04:19:42 MET 1999, aeb: added PR_GET_PDEATHSIG
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.\" Modified 27 Jun 02, Michael Kerrisk
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.\" Added PR_SET_DUMPABLE, PR_GET_DUMPABLE,
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.\" PR_SET_KEEPCAPS, PR_GET_KEEPCAPS
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.\" Modified 2006-08-30 Guillem Jover <guillem@hadrons.org>
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.\" Updated Linux versions where the options where introduced.
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.\" Added PR_SET_TIMING, PR_GET_TIMING, PR_SET_NAME, PR_GET_NAME,
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.\" PR_SET_UNALIGN, PR_GET_UNALIGN, PR_SET_FPEMU, PR_GET_FPEMU,
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.\" PR_SET_FPEXC, PR_GET_FPEXC
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.\"
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.TH PRCTL 2 2007-07-27 "Linux" "Linux Programmer's Manual"
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.SH NAME
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prctl \- operations on a process
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.SH SYNOPSIS
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.nf
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.B #include <sys/prctl.h>
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.sp
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.BI "int prctl(int " option ", unsigned long " arg2 ", unsigned long " arg3 ,
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.BI " unsigned long " arg4 ", unsigned long " arg5 );
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.fi
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.SH DESCRIPTION
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.BR prctl ()
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is called with a first argument describing what to do
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(with values defined in <\fIlinux/prctl.h\fP>), and further
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parameters with a significance depending on the first one.
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The first argument can be:
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.TP
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.B PR_SET_PDEATHSIG
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(since Linux 2.1.57)
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Set the parent process death signal
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of the calling process to \fIarg2\fP (either a signal value
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in the range 1..maxsig, or 0 to clear).
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This is the signal that the calling process will get when its
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parent dies.
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This value is cleared upon a
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.BR fork (2).
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.TP
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.B PR_GET_PDEATHSIG
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(Since Linux 2.3.15)
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Read the current value of the parent process death signal
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into the (int *) \fIarg2\fP.
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.TP
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.B PR_SET_DUMPABLE
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(Since Linux 2.3.20)
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Set the state of the flag determining whether core dumps are produced
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for this process upon delivery of a signal whose default behavior is
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to produce a core dump.
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(Normally this flag is set for a process by default, but it is cleared
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when a set-user-ID or set-group-ID program is executed and also by
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various system calls that manipulate process UIDs and GIDs).
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In kernels up to and including 2.6.12,
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.I arg2
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must be either 0 (process is not dumpable) or 1 (process is dumpable).
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Between kernels 2.6.13 and 2.6.17, the value 2 was also permitted,
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which caused any binary which normally would not be dumped
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to be dumped readable by root only;
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for security reasons, this feature has been removed.
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.\" See http://marc.theaimsgroup.com/?l=linux-kernel&m=115270289030630&w=2
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.\" Subject: Fix prctl privilege escalation (CVE-2006-2451)
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.\" From: Marcel Holtmann <marcel () holtmann ! org>
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.\" Date: 2006-07-12 11:12:00
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(See also the description of
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.I /proc/sys/fs/suid_dumpable
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in
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.BR proc (5).)
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.TP
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.B PR_GET_DUMPABLE
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(Since Linux 2.3.20)
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Return (as the function result) the current state of the calling
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process's dumpable flag.
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.\" Since Linux 2.6.13, the dumpable flag can have the value 2,
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.\" but in 2.6.13 PR_GET_DUMPABLE simply returns 1 if the dumpable
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.\" flags has a non-zero value. This was fixed in 2.6.14.
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.TP
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.B PR_SET_KEEPCAPS
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(Since Linux 2.2.18)
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Set the state of the process's "keep capabilities" flag,
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which determines whether the process's effective and permitted
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capability sets are cleared when a change is made to the process's user IDs
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such that the process's real UID, effective UID, and saved set-user-ID
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all become non-zero when at least one of them previously had the value 0.
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(By default, these credential sets are cleared).
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.I arg2
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must be either 0 (capabilities are cleared) or 1 (capabilities are kept).
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.TP
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.B PR_GET_KEEPCAPS
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(Since Linux 2.2.18)
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Return (as the function result) the current state of the calling process's
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"keep capabilities" flag.
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.TP
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.B PR_SET_TIMING
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(Since Linux 2.6.0-test4)
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Set whether to use (normal, traditional) statistical process timing or
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accurate timestamp based process timing, by passing \fBPR_TIMING_STATISTICAL\fP
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or \fBPR_TIMING_TIMESTAMP\fP to \fIarg2\fP.
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.TP
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.B PR_GET_TIMING
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(Since Linux 2.6.0-test4)
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Return (as the function result) which process timing method is currently
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in use.
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.TP
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.B PR_SET_NAME
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(Since Linux 2.6.9)
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Set the process name for the calling process to \fIarg2\fP.
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.TP
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.B PR_GET_NAME
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(Since Linux 2.6.11)
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Get the process name for the calling process from \fIarg2\fP.
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.TP
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.B PR_GET_ENDIAN
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(Since Linux 2.6.18, PowerPC only)
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Return the endian-ness of the calling process.
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.TP
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.B PR_SET_ENDIAN
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(Since Linux 2.6.18, PowerPC only)
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Set the endian-ness of the calling process to the value given
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in \fIarg2\fP, which should be one of the following:
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.BR PR_ENDIAN_BIG ,
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.BR PR_ENDIAN_LITTLE ,
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or
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.BR PR_ENDIAN_PPC_LITTLE
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(PowerPC pseudo little endian).
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.TP
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.B PR_SET_UNALIGN
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(Only on: ia64, since Linux 2.3.48; parisc, since Linux 2.6.15;
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PowerPC, since Linux 2.6.18)
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.\" FIXME . On alpha in 2.6.22-rc4?
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Set unaligned access control bits to \fIarg2\fP.
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Pass
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\fBPR_UNALIGN_NOPRINT\fP to silently fix up unaligned user accesses,
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or \fBPR_UNALIGN_SIGBUS\fP to generate
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.B SIGBUS
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on unaligned user access.
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.TP
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.B PR_GET_UNALIGN
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(see
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.B PR_SET_UNALIGN
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for information on versions and architectures)
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Get unaligned access control bits from \fIarg2\fP.
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.TP
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.B PR_SET_FPEMU
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(Since Linux 2.4.18, 2.5.9, only on ia64)
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Set floating-point emulation control bits to \fIarg2\fP.
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Pass \fBPR_FPEMU_NOPRINT\fP to silently emulate fp operations accesses, or
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\fBPR_FPEMU_SIGFPE\fP to not emulate fp operations and send
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.B SIGFPE
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instead.
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.TP
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.B PR_GET_FPEMU
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(Since Linux 2.4.18, 2.5.9, only on ia64)
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Get floating-point emulation control bits from \fIarg2\fP.
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.TP
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.B PR_SET_FPEXC
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(Since Linux 2.4.21, 2.5.32, only on PowerPC)
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Set floating-point exception mode to \fIarg2\fP.
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Pass \fBPR_FP_EXC_SW_ENABLE\fP to use FPEXC for FP exception enables,
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\fBPR_FP_EXC_DIV\fP for floating point divide by zero,
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\fBPR_FP_EXC_OVF\fP for floating point overflow,
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\fBPR_FP_EXC_UND\fP for floating point underflow,
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\fBPR_FP_EXC_RES\fP for floating point inexact result,
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\fBPR_FP_EXC_INV\fP for floating point invalid operation,
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\fBPR_FP_EXC_DISABLED\fP for FP exceptions disabled,
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\fBPR_FP_EXC_NONRECOV\fP for async non-recoverable exception mode,
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\fBPR_FP_EXC_ASYNC\fP for async recoverable exception mode,
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\fBPR_FP_EXC_PRECISE\fP for precise exception mode.
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.TP
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.B PR_GET_FPEXC
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(Since Linux 2.4.21, 2.5.32, only on PowerPC)
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Get floating-point exception mode from \fIarg2\fP.
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.SH "RETURN VALUE"
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.B PR_GET_DUMPABLE
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and
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.B PR_GET_KEEPCAPS
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return 0 or 1 on success.
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All other
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.I option
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values return 0 on success.
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On error, \-1 is returned, and
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.I errno
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is set appropriately.
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.SH ERRORS
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.TP
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.B EINVAL
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The value of
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.I option
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is not recognized, or it is
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.B PR_SET_PDEATHSIG
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and
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.I arg2
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is not zero or a signal number.
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.SH VERSIONS
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The
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.BR prctl ()
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system call was introduced in Linux 2.1.57.
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.\" The library interface was added in glibc 2.0.6
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.SH "CONFORMING TO"
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This call is Linux specific.
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IRIX has a
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.BR prctl ()
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system call (also introduced in Linux 2.1.44
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as irix_prctl on the MIPS architecture),
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with prototype
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.sp
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.BI "ptrdiff_t prctl(int " option ", int " arg2 ", int " arg3 );
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.sp
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and options to get the maximum number of processes per user,
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get the maximum number of processors the calling process can use,
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find out whether a specified process is currently blocked,
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get or set the maximum stack size, etc.
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.SH "SEE ALSO"
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.BR signal (2),
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.BR core (5)
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