NAME

unlockpt − unlock a STREAMS pty master and slave pair

SYNOPSIS

int unlockpt (int fildes);

DESCRIPTION

The passed parameter, fildes, is a file descriptor that is returned from a successful open of a master pty (pseudo-terminal) device. The unlockpt() function unlocks a slave pty from its associated master counterpart.  It does this by clearing a lock flag so that the slave pty can be opened. For security reason, grantpt(3C) must be executed before unlockpt(3C).

RETURN VALUE

Upon successful completion, the unlockpt() function returns a value of 0 (zero).  Otherwise, it returns a value of -1. 

Failure may result under the following conditions:

• The file descriptor specified by the fildes parameter is not an open file descriptor. 

• The file descriptor specified by the fildes parameter is not associated with a STREAMS pty master device. 

EXAMPLES

The following example shows how unlockpt is typically used. 

int fd_master, fd_slave;
char *slave;
...

fd_master = open("/dev/ptmx", O_RDWR);
grantpt(fd_master);
unlockpt(fd_master);
slave = ptsname(fd_master);
fd_slave = open(slave, O_RDWR);
ioctl(fd_slave, I_PUSH, "ptem");
ioctl(fd_slave, I_PUSH, "ldterm");

AUTHOR

unlockpt() was developed by HP and OSF. 

SEE ALSO

open(2), grantpt(3C), ptsname(3C), ptm(7), pts(7), ptem(7). 

Hewlett-Packard Company  —  HP-UX Release 10.20:  July 1996