unlockpt() — Unlock a pseudoterminal master and slave pair
Standards
Standards / Extensions | C or C++ | Dependencies |
---|---|---|
XPG4.2 |
both |
Format
#define _XOPEN_SOURCE_EXTENDED 1
#include <stdlib.h>
int unlockpt(int fildes);
General description
The unlockpt() function unlocks the slave pseudoterminal device associated with the master to which fildes refers.
Portable applications must call unlockpt() before opening the slave side of a pseudoterminal device.
Returned value
If successful, unlockpt() returns 0.
If unsuccessful, unlockpt() returns -1 and sets
errno to one of the following values:
- Error Code
- Description
- EACCESS
- Either a grantpt() has not yet been issued, or an unlockpt() has already been issued. An unlockpt() must be issued after a grantpt(), and can only be issued once.
- EBADF
- The fildes argument is not a file descriptor open for writing.
- EINVAL
- The fildes argument is not associated with a master pseudoterminal device.