SYSCALL

Section: Linux Programmer's Manual (2)
Updated: 2007-07-26
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NAME

syscall - indirect system call

SYNOPSIS

#define _GNU_SOURCE        /* or _BSD_SOURCE or _SVID_SOURCE */
#include <unistd.h>
#include <sys/syscall.h>   /* For SYS_xxx definitions */

int syscall(int number, ...);

DESCRIPTION

syscall() performs the system call whose assembly language interface has the specified number with the specified arguments. Symbolic constants for system calls can be found in the header file <sys/syscall.h>.

RETURN VALUE

The return value is defined by the system call being invoked. In general, a 0 return value indicates success. A -1 return value indicates an error, and an error code is stored in errno.

NOTES

syscall() first appeared in 4BSD.

EXAMPLE

#define _GNU_SOURCE
#include <unistd.h>
#include <sys/syscall.h>
#include <sys/types.h>

int
main(int argc, char *argv[])
{
    pid_t tid;

    tid = syscall(SYS_gettid);
}

COLOPHON

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