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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);
       }

SEE ALSO

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

COLOPHON

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