- online man pages   

Linux man pages : prctl (2)
PRCTL(2)		   Linux Programmer's Manual		      PRCTL(2)


prctl - operations on a process


#include <sys/prctl.h> int prctl(int option, unsigned long arg2, unsigned long arg3 , unsigned long arg4, unsigned long arg5);


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.


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.


EINVAL The value of option is not recognized, or it is PR_SET_PDEATHSIG and arg2 is not zero or a signal number.


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_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., etc.


The prctl() systemcall was introduced in Linux 2.1.57. There is no prctl() library call as yet.


signal(2) Linux 2.4.18 2002-06-27 PRCTL(2)