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TTYNAME(3)            DragonFly Library Functions Manual            TTYNAME(3)


NAME

     ttyname, ttyname_r, isatty - get name of associated terminal (tty) from
     file descriptor


LIBRARY

     Standard C Library (libc, -lc)


SYNOPSIS

     #include <unistd.h>

     char *
     ttyname(int fd);

     int
     ttyname_r(int fd, char *buf, size_t len);

     int
     isatty(int fd);


DESCRIPTION

     These functions operate on the system file descriptors for terminal type
     devices.  These descriptors are not related to the standard I/O FILE
     typedef, but refer to the special device files found in /dev and named
     /dev/ttyxx and for which an entry exists in the initialization file
     /etc/ttys.  (See ttys(5).)

     The isatty() function determines if the file descriptor fd refers to a
     valid terminal type device.

     The ttyname() function gets the related device name of a file descriptor
     for which isatty() is true.

     The ttyname() function returns the name stored in a static buffer which
     will be overwritten on subsequent calls.  The ttyname_r() function takes
     a buffer and length as arguments to avoid this problem.


RETURN VALUES

     The isatty() function returns 1 if the file descriptor refers to a valid
     terminal device and 0 otherwise.

     The ttyname() function returns the null terminated name if the device is
     found and isatty() is true; otherwise a NULL pointer is returned.  The
     ttyname_r() function returns 0 if successful.  Otherwise an error number
     is returned.


FILES

     /dev/*
     /etc/ttys


ERRORS

     The ttyname(), ttyname_r(), and isatty() functions may fail and return
     the following error codes:

     [EBADF]            The fd is not a valid open file descriptor.

     [ENOTTY]           The fd is not associated with a terminal.

     [ERANGE]           The bufsize argument is smaller than the length of the
                        string to be returned.


SEE ALSO

     ioctl(2), ttys(5)


HISTORY

     The isatty() and ttyname() functions appeared in Version 7 AT&T UNIX.
     The ttyname_r() function appeared in FreeBSD 6.0.

DragonFly 5.7-DEVELOPMENT     September 10, 2019     DragonFly 5.7-DEVELOPMENT

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