POSIX_OPENPT(3) BSD Library Functions Manual POSIX_OPENPT(3)NAMEposix_openpt — open a pseudo-terminal device
LIBRARY
Standard C Library (libc, -lc)
SYNOPSIS
#include <stdlib.h>
#include <fcntl.h>
int
posix_openpt(int oflag);
DESCRIPTION
The posix_openpt() function allocates a new pseudo-terminal and estab‐
lishes a connection with its master device. A slave device shall be cre‐
ated in /dev/pts. After the pseudo-terminal has been allocated, the
slave will already have the proper permissions (see grantpt(3)) without
the need to call grantpt(3). The name of the slave device can be deter‐
mined by calling ptsname(3).
The file status flags and file access modes of the open file description
shall be set according to the value of oflag. Values for oflag are con‐
structed by a bitwise-inclusive OR of flags from the following list,
defined in <fcntl.h>:
O_RDWR Open for reading and writing.
O_NOCTTY If set posix_openpt() shall not cause the terminal device to
become the controlling terminal for the process.
The posix_openpt() function shall fail when oflag contains other values.
RETURN VALUES
Upon successful completion, the posix_openpt() function shall allocate a
new pseudo-terminal device and return a non-negative integer representing
a file descriptor, which is connected to its master device. Otherwise,
-1 shall be returned and errno set to indicate the error.
ERRORS
The posix_openpt() function shall fail if:
[ENFILE] The system file table is full.
[EINVAL] The value of oflag is not valid.
SEE ALSOopen(2), grantpt(3), ptsname(3), unlockpt(3), tty(4)RATIONALE
The standards committee did not want to directly expose the cloning
device and 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”).
HISTORY
The posix_openpt() function appeared in DragonFly 2.3.
NOTES
The posix_openpt() is equivalent in DragonFly to calling open(2) on
/dev/ptmx.
The flag O_NOCTTY is included for compatibility; in DragonFly, opening a
terminal does not cause it to become a process's controlling terminal.
BSD September 10, 2009 BSD
