NAME | SYNOPSIS | DESCRIPTION | RETURN VALUE | NOTES | EXAMPLE | SEE ALSO | COLOPHON

SYSCALL(2)                    Linux Programmer's Manual                    SYSCALL(2)

NAME         top

       syscall - indirect system call

SYNOPSIS         top

       #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         top

       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         top

       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         top

       syscall() first appeared in 4BSD.

EXAMPLE         top

       #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);
       }

SEE ALSO         top

       _syscall(2), intro(2), syscalls(2)

COLOPHON         top

       This page is part of release 3.08 of the Linux man-pages project.  A
       description of the project, and information about reporting bugs, can be found
       at http://www.kernel.org/doc/man-pages/.

Linux                                 2007-07-26                           SYSCALL(2)