Visit Our UNIX and Linux User Community

Linux and UNIX Man Pages

Test Your Knowledge in Computers #131
Difficulty: Easy
UNIX certification is based on the 'Single Unix Specification' which is an extension of IEEE 1003 (POSIX).
True or False?
Linux & Unix Commands - Search Man Pages

posix_openpt(3) [netbsd man page]

POSIX_OPENPT(3) 					   BSD Library Functions Manual 					   POSIX_OPENPT(3)

NAME
posix_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 searches for an unused master pseudo-terminal device, opens it, and returns a file descriptor associated with 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''). BSD
May 25, 2004 BSD

Check Out this Related Man Page

posix_openpt(3C)					   Standard C Library Functions 					  posix_openpt(3C)

NAME
posix_openpt - open a pseudo terminal device SYNOPSIS
#include <stdlib.h> #include <fcntl.h> int posix_openpt(int oflag); DESCRIPTION
The posix_openpt() function establishes a connection between a master device for a pseudo-terminal and a file descriptor. The file descrip- tor is used by other I/O functions that refer to that pseudo-terminal. The file status flags and file access modes of the open file description are set according to the value of oflag. Values for oflag are constructed 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() does not cause the terminal device to become the controlling terminal for the process. The behavior of other values for the oflag argument is unspecified. RETURN VALUES
Upon successful completion, the posix_openpt() function opens a master pseudo-terminal device and returns a non-negative integer represent- ing the lowest numbered unused file descriptor. Otherwise, -1 is returned and errno is set to indicate the error. ERRORS
The posix_openpt() function will fail if: EMFILE {OPEN_MAX} file descriptors are currently open in the calling process. ENFILE The maximum allowable number of files is currently open in the system. The posix_openpt() function may fail if: EINVAL The value of oflag is not valid. EAGAIN Out of pseudo-terminal resources. ENOSR Out of STREAMS resources. EXAMPLES
Example 1 Open a pseudo-terminal. The following example opens a pseudo-terminal and returns the name of the slave device and a file descriptor. #include fcntl.h> #include stdio.h> int masterfd, slavefd; char *slavedevice; masterfd = posix_openpt(O_RDWR|O_NOCTTY); if (masterfd == -1 || grantpt (masterfd) == -1 || unlockpt (masterfd) == -1 || (slavedevice = ptsname (masterfd)) == NULL) return -1; printf("slave device is: %s ", slavedevice); slavefd = open(slave, O_RDWR|O_NOCTTY); if (slavefd < 0) return -1; USAGE
This function provieds a method for portably obtaining a file descriptor of a master terminal device for a pseudo-terminal. The grantpt(3C) and ptsname(3C) functions can be used to manipulate mode and ownership permissions and to obtain the name of the slave device, respec- tively. ATTRIBUTES
See attributes(5) for descriptions of the following attributes: +-----------------------------+-----------------------------+ | ATTRIBUTE TYPE | ATTRIBUTE VALUE | +-----------------------------+-----------------------------+ |Interface Stability |Standard | +-----------------------------+-----------------------------+ |MT-Level |MT-Safe | +-----------------------------+-----------------------------+ SEE ALSO
open(2), grantpt(3C), ptsname(3C), unlockpt(3C), attributes(5), standards(5) SunOS 5.11 1 Dec 2003 posix_openpt(3C)

Featured Tech Videos