May 15, 2003 SOCKATMARK 3

### NAME

sockatmark - determine whether a socket is at the out-of-band mark

### LIBRARY

Standard C Library (libc, -lc)

### SYNOPSIS

```int` sockatmark(```int s`)

### DESCRIPTION

The sockatmark function determines whether the socket referenced by the file descriptor ```s` is at the out-of-band mark.

### RETURN VALUES

If successful, the sockatmark function returns 1 to indicate that the socket is at an out-of-band mark; 0 is returned if there is no out-of-band mark or the mark is preceded by in-band data. Otherwise, -1 is returned and errno is set to indicate the error.

### ERRORS

The sockatmark function will fail if:

[```EBADF`]
  The argument ```s` is not a valid file descriptor.

[```ENOTTY`]
  The file descriptor ```s` does not refer to a socket.

### SEE ALSO

ioctl(2), recv(2), socket(2) (see```/usr/share/doc/psd/20.ipctut`) (see```/usr/share/doc/psd/21.ipc`)

### STANDARDS

The sockatmark function conforms to IEEE Std 1003.1-2001 (``POSIX.1'') .

### HISTORY

The sockatmark function appeared in IEEE Std 1003.1g-2000 (``POSIX.1'') as a replacement for the ```SIOCATMARK` ioctl(2) interface.