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ttyname(3)
NAME
  ttyname, isatty, ttyname_r -	Get the name of a terminal

LIBRARY
  Standard C Library (libc.so, libc.a)

SYNOPSIS
  #include <unistd.h>

  char *ttyname(
	  int file-descriptor);

  int isatty(
	  int file-descriptor);

  int ttyname_r(
	  int file-descriptor,
	  char *buffer,
	  int len);

STANDARDS
  Interfaces documented on this reference page conform to industry standards
  as follows:

  ttyname_r(): POSIX.1c

  isatty(), ttyname():	XPG4, XPG4-UNIX

  Refer to the standards(5) reference page for more information about
  industry standards and associated tags.

PARAMETERS
  file-descriptor
	    Specifies an open file descriptor.

  buffer    Points to a buffer in which the terminal name is stored.

  len	    Specifies the length of the buffer pointed to by the buffer
	    parameter.

DESCRIPTION
  The ttyname() function gets the name of a terminal.  It returns a pointer
  to a string containing the null-terminated pathname of the terminal device
  associated with the file-descriptor parameter.

  The isatty() function determines if the device associated with the file-
  descriptor parameter is a terminal.

NOTES
  The ttyname() function returns a pointer to thread-specific data.
  Subsequent calls to this function from the same thread overwrite this data.

RETURN VALUES
  Upon successful completion, the ttyname() function returns a pointer to a
  string identifying a terminal device.	 A NULL pointer is returned if the
  file-descriptor parameter does not describe a terminal device in the /dev
  directory.

  Upon successful completion, the isatty() function returns a value of 1 if
  the specified file-descriptor parameter is associated with a terminal.
  Otherwise, it returns a value of zero (0).

  [POSIX]  Upon successful completion, the ttyname_r() function stores the
  terminal name as a null-terminated string in the buffer pointed to by the
  buffer parameter and returns a value of 0 (zero).  Otherwise, it returns an
  error number.

  [Digital]  The obsolete version of ttyname_r() functions the same way as
  the POSIX version, except it returns a -1 upon unsuccessful completion.

ERRORS
  If the isatty() function fails, errno may be set to the following value:

  [ENOTTY]  The file associated with file-descriptor is not a terminal.

  If the ttyname_r() function fails, errno may be set to the following value:

  [EINVAL]  The buffer parameter is a null pointer or the len parameter was
	    too short to store the string.

RELATED INFORMATION
  Functions: ttyslot(3)

  Standards: standards(5)