May 25, 2004 POSIX_OPENPT 3

### NAME

posix_openpt - open a pseudo-terminal device

### LIBRARY

Standard C Library (libc, -lc)

### SYNOPSIS

```int` posix_openpt(```int oflag`)

### DESCRIPTION

posix_openpt(``) Searches for an unused master pseudo-terminal device, opens it, and returns a file descriptor associated the now used pseudo-terminal device. The ```oflag` argument has the same meaning as in the open(2) call.

### RETURN VALUES

If successful, posix_openpt(``) returns a non-negative integer, which corresponds to a file descriptor pointing to the master pseudo-terminal device. Otherwise, a value of -1 is returned and errno is set to indicate the error.

### SEE ALSO

ioctl(2), open(2), grantpt(3), ptsname(3), unlockpt(3)

### RATIONALE

The standards committee did not want to directly expose the cloning device, thus decided to wrap the functionality in this function. The equivalent code would be: `

            int
            posix_openpt(int oflag) {
                    return open("/dev/ptmx", oflag);
            }

`

### STANDARDS

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