unlockpt(3C) Standard C Library Functions unlockpt(3C)NAME
unlockpt - unlock a pseudo-terminal master/slave pair
SYNOPSIS
#include <stdlib.h>
int unlockpt(int fildes);
DESCRIPTION
The unlockpt() function unlocks the slave pseudo-terminal device associated with the master to which fildes refers.
Portable applications must call unlockpt() before opening the slave side of a pseudo-terminal device.
RETURN VALUES
Upon successful completion, unlockpt() returns 0. Otherwise, it returns -1 and sets errno to indicate the error.
ERRORS
The unlockpt() function may fail if:
EBADF The fildes argument is not a file descriptor open for writing.
EINVAL The fildes argument is not associated with a master pseudo-terminal device.
ATTRIBUTES
See attributes(5) for descriptions of the following attributes:
+-----------------------------+-----------------------------+
| ATTRIBUTE TYPE | ATTRIBUTE VALUE |
+-----------------------------+-----------------------------+
|Interface Stability |Standard |
+-----------------------------+-----------------------------+
|MT-Level |Safe |
+-----------------------------+-----------------------------+
SEE ALSO open(2), grantpt(3C), ptsname(3C), attributes(5), standards(5)
STREAMS Programming Guide
SunOS 5.11 14 Aug 2002 unlockpt(3C)
Check Out this Related Man Page
PTSNAME(3) BSD Library Functions Manual PTSNAME(3)NAME
grantpt, ptsname, unlockpt -- pseudo-terminal access functions
LIBRARY
Standard C Library (libc, -lc)
SYNOPSIS
#include <stdlib.h>
int
grantpt(int fildes);
char *
ptsname(int fildes);
int
unlockpt(int fildes);
DESCRIPTION
The grantpt(), ptsname(), and unlockpt() functions allow access to pseudo-terminal devices. These three functions accept a file descriptor
that references the master half of a pseudo-terminal pair. This file descriptor is created with posix_openpt(2).
The grantpt() function is used to establish ownership and permissions of the slave device counterpart to the master device specified with
fildes. The slave device's ownership is set to the real user ID of the calling process, and the permissions are set to user readable-
writable and group writable. The group owner of the slave device is also set to the group ``tty''.
The ptsname() function returns the full pathname of the slave device counterpart to the master device specified with fildes. This value can
be used to subsequently open the appropriate slave after posix_openpt(2) and grantpt() have been called.
The unlockpt() function clears the lock held on the pseudo-terminal pair for the master device specified with fildes.
RETURN VALUES
The grantpt() and unlockpt() functions return the value 0 if successful; otherwise the value -1 is returned and the global variable errno is
set to indicate the error.
The ptsname() function returns a pointer to the name of the slave device on success; otherwise a NULL pointer is returned.
ERRORS
The grantpt(), ptsname() and unlockpt() functions may fail and set errno to:
[EBADF] fildes is not a valid open file descriptor.
[EINVAL] fildes is not a master pseudo-terminal device.
In addition, the grantpt() function may set errno to:
[EACCES] The slave pseudo-terminal device could not be accessed.
SEE ALSO posix_openpt(2), pts(4), tty(4)STANDARDS
The ptsname() function conforms to IEEE Std 1003.1-2008 (``POSIX.1'').
This implementation of grantpt() and unlockpt() does not conform to IEEE Std 1003.1-2008 (``POSIX.1''), because it depends on posix_openpt(2)
to create the pseudo-terminal device with proper permissions in place. It only validates whether fildes is a valid pseudo-terminal master
device. Future revisions of the specification will likely allow this behaviour, as stated by the Austin Group.
HISTORY
The grantpt(), ptsname() and unlockpt() functions appeared in FreeBSD 5.0.
BSD August 20, 2008 BSD