ttyname(3)ttyname(3)NAME
ttyname, isatty, ttyname_r - Get the name of a terminal
SYNOPSIS
#include <unistd.h>
char *ttyname(
int file-descriptor ); int isatty(
int file-descriptor ); int ttyname_r(
int file-descriptor,
char *buffer,
int len );
LIBRARY
Standard C Library (libc)
STANDARDS
Interfaces documented on this reference page conform to industry stan‐
dards as follows:
ttyname_r(): POSIX.1c
isatty(), ttyname(): XSH4.2
Refer to the standards(5) reference page for more information about
industry standards and associated tags.
PARAMETERS
Specifies an open file descriptor. Points to a buffer in which the
terminal name is stored. 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 ter‐
minal 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. Sub‐
sequent 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 termi‐
nal. 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.
[Tru64 UNIX] The obsolete version of ttyname_r() functions the same
way as the POSIX version, except it returns a -1 upon unsuccessful com‐
pletion.
ERRORS
If the isatty() function fails, errno may be set to the following
value: The file associated with file-descriptor is not a terminal.
If the ttyname_r() function fails, errno may be set to the following
value: The buffer parameter is a null pointer or the len parameter was
too short to store the string.
SEE ALSO
Functions: ttyslot(3)
Standards: standards(5)ttyname(3)