PRCTL(2) Linux Programmer's Manual PRCTL(2)NAMEprctl - operations on a process
SYNOPSIS
#include <sys/prctl.h>
int prctl(int option, unsigned long arg2, unsigned long arg3 , unsigned
long arg4, unsigned long arg5);
DESCRIPTIONprctl() is called with a first argument describing what to do (with
values defined in <linux/prctl.h>), and further parameters with a sig‐
nificance 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
process 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-user-ID or set-group-ID program is executed
and also by various system calls that manipulate process UIDs
and GIDs). In kernels up to and including 2.6.12, arg2 must be
either 0 (process is not dumpable) or 1 (process is dumpable).
Since kernel 2.6.13, the value 2 is also permitted; this causes
any binary which normally would not be dumped to be dumped read‐
able by root only. (See also the description of
/proc/sys/fs/suid_dumpable in proc(5).)
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 the process's real UID, effective UID, and
saved set-user-ID all 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.
RETURN VALUE
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.
CONFORMING TO
This call is Linux-specific. 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 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.
AVAILABILITY
The prctl() system call was introduced in Linux 2.1.57.
SEE ALSOsignal(2), core(5)Linux 2.4.18 2002-06-27 PRCTL(2)
