# ttyname

## PROLOG



           This manual page is part of the POSIX Programmer's Manual.  The
           Linux implementation of this interface may differ (consult the
           corresponding Linux manual page for details of Linux behavior), or
           the interface may not be implemented on Linux.
    


## NAME



           ttyname, ttyname_r — find the pathname of a terminal
    


## SYNOPSIS



           #include <unistd.h>
    
           char *ttyname(int _fildes_);
           int ttyname_r(int _fildes_ , char *_name_ , size_t _namesize_);
    


## DESCRIPTION



           The _ttyname_() function shall return a pointer to a string
           containing a null-terminated pathname of the terminal associated
           with file descriptor _fildes_.  The application shall not modify the
           string returned. The returned pointer might be invalidated or the
           string content might be overwritten by a subsequent call to
           _ttyname_().  The returned pointer and the string content might also
           be invalidated if the calling thread is terminated.
    
           The _ttyname_() function need not be thread-safe.
    
           The _ttyname_r_() function shall store the null-terminated pathname
           of the terminal associated with the file descriptor _fildes_ in the
           character array referenced by _name_.  The array is _namesize_
           characters long and should have space for the name and the
           terminating null character. The maximum length of the terminal
           name shall be {TTY_NAME_MAX}.
    


## RETURN VALUE



           Upon successful completion, _ttyname_() shall return a pointer to a
           string. Otherwise, a null pointer shall be returned and _errno_ set
           to indicate the error.
    
           If successful, the _ttyname_r_() function shall return zero.
           Otherwise, an error number shall be returned to indicate the
           error.
    


## ERRORS



           The _ttyname_() function may fail if:
    
           **EBADF** The _fildes_ argument is not a valid file descriptor.
    
           **ENOTTY** The file associated with the _fildes_ argument is not a
                  terminal.
    
           The _ttyname_r_() function may fail if:
    
           **EBADF** The _fildes_ argument is not a valid file descriptor.
    
           **ENOTTY** The file associated with the _fildes_ argument is not a
                  terminal.
    
           **ERANGE** The value of _namesize_ is smaller than the length of the
                  string to be returned including the terminating null
                  character.
    
           _The following sections are informative._
    


## EXAMPLES



           None.
    


## APPLICATION USAGE



           None.
    


## RATIONALE



           The term ``terminal'' is used instead of the historical term
           ``terminal device'' in order to avoid a reference to an undefined
           term.
    
           The thread-safe version places the terminal name in a user-
           supplied buffer and returns a non-zero value if it fails. The non-
           thread-safe version may return the name in a static data area that
           may be overwritten by each call.
    


## FUTURE DIRECTIONS



           None.
    


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