PRCTL(2) Linux Programmer's Manual PRCTL(2)
NAME
prctl - operations on a process
SYNOPSIS
#include<sys/prctl.h>
intprctl(int option,unsignedlong arg2,unsignedlong arg3 ,unsigned
long arg4,unsignedlong arg5);
DESCRIPTION
prctl is called with a first argument describing what to do (with val-
ues defined in <linux/prctl.h>), and further parameters with a signifi-
cance depending on the first one. The first argument can be:
PR_SET_PDEATHSIG
(since Linux 2.1.57) Set the parent process death signal of the
current process to arg2 (either a signal value in the range
1..maxsig, or 0 to clear). This is the signal that the current
process will get when its parent dies. This value is cleared
upon a fork().
PR_GET_PDEATHSIG
(since Linux 2.3.15) Read the current value of the parent pro-
cess death signal into the (int *) arg2.
PR_SET_DUMPABLE
(Since Linux 2.4) Set the state of the flag determining whether
core dumps are produced for this process upon delivery of a sig-
nal whose default behaviour is to produce a core dump. (Nor-
mally this flag is set for a process by default, but it is
cleared when a set-UID or set-GID program is executed and also
by various system calls that manipulate process UIDs and GIDs).
arg2 must be either 0 (process is not dumapable) or 1 (process
is dumpable).
PR_GET_DUMPABLE
(Since Linux 2.4) Return (as the function result) the current
state of the calling process's dumpable flag.
PR_SET_KEEPCAPS
Set the state of the process's "keep capabilities" flag, which
determines whether the process's effective and permitted capa-
bility sets are cleared when a change is made to the process's
user IDs such that all of the process's real, effective, and
saved set user IDs become non-zero when at least one of them
previously had the value 0. (By default, these credential sets
are cleared). arg2 must be either 0 (capabilities are cleared)
or 1 (capabilities are kept).
PR_GET_KEEPCAPS
Return (as the function result) the current state of the calling
process's "keep capabilities" flag.
RETURNVALUE
PR_GET_DUMPABLE and PR_GET_KEEPCAPS return 0 or 1 on success. All
other option values return 0 on success. On error, -1 is returned, and
errno is set appropriately.
ERRORS
EINVAL The value of option is not recognized, or it is PR_SET_PDEATHSIG
and arg2 is not zero or a signal number.
CONFORMINGTO
This call is Linux-specific. IRIX has a prctl system call (also intro-
duced in Linux 2.1.44 as irix_prctl on the MIPS architecture), with
prototype
ptrdiff_tprctl(int option,int arg2,int arg3);
and options 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 maxi-
mum stack size, etc., etc.
AVAILABILITY
The prctl() systemcall was introduced in Linux 2.1.57. There is no
prctl() library call as yet.
SEEALSO
signal(2)
Linux 2.4.18 2002-06-27 PRCTL(2)
Free eBook: 
