syscall(2)

NAME

syscall, __syscall - indirect system call

LIBRARY

Standard C Library (libc, -lc)

SYNOPSIS

#include <sys/syscall.h>
#include <unistd.h>
int
syscall(int number, ...);
off_t
__syscall(quad_t number, ...);

DESCRIPTION

The syscall() function performs the system call whose assem

bly language
interface has the specified number with the specified argu

ments. Symbolic constants for system calls can be found in the header

file The
__syscall() form should be used when one or more of the ar

guments is a
64-bit argument to ensure that argument alignment is cor

rect. This system call is useful for testing new system calls that do not

have entries
in the C library.

RETURN VALUES

The return values are defined by the system call being in

voked. In general, a 0 return value indicates success. A -1 return value

indicates an
error, and an error code is stored in errno.

HISTORY

The syscall() function appeared in 4.0BSD.

BUGS

There is no way to simulate system calls that have multiple

return values
such as pipe(2).

BSD June 16, 1993

BSD