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syscall(2) [osx man page]

SYSCALL(2)						      BSD System Calls Manual							SYSCALL(2)

syscall -- indirect system call SYNOPSIS
#include <sys/syscall.h> #include <unistd.h> int syscall(int number, ...); DESCRIPTION
Syscall() performs the system call whose assembly language interface has the specified number with the specified arguments. Symbolic con- stants for system calls can be found in the header file <sys/syscall.h>. This function 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 invoked. In general, a 0 return value indicates success. A -1 return value indicates an error, and an error code is stored in errno. BUGS
There is no way to simulate system calls that have multiple return values such as pipe(2). HISTORY
The syscall() function call appeared in 4.0BSD. 4th Berkeley Distribution June 23, 2008 4th Berkeley Distribution

Check Out this Related Man Page

syscall(3UCB)					     SunOS/BSD Compatibility Library Functions					     syscall(3UCB)

syscall - indirect system call SYNOPSIS
/usr/ucb/cc [ flag ... ] file ... #include <sys/syscall.h> int syscall(number, arg, ...); DESCRIPTION
syscall() performs the function whose assembly language interface has the specified number, and arguments arg .... Symbolic constants for functions can be found in the header <sys/syscall.h>. RETURN VALUES
On error syscall() returns -1 and sets the external variable errno (see intro(2)). FILES
<sys/syscall.h> SEE ALSO
intro(2), pipe(2) NOTES
Use of these interfaces should be restricted to only applications written on BSD platforms. Use of these interfaces with any of the system libraries or in multi-thread applications is unsupported. WARNINGS
There is no way to use syscall() to call functions such as pipe(2) which return values that do not fit into one hardware register. Since many system calls are implemented as library wrappers around traps to the kernel, these calls may not behave as documented when called from syscall(), which bypasses these wrappers. For these reasons, using syscall() is not recommended. SunOS 5.10 22 Jan 1993 syscall(3UCB)
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