Technical Reference: Base Operating System and Extensions , Volume 2

ttyname or isatty Subroutine

Purpose

Gets the name of a terminal or determines if the device is a terminal.

Library

Standard C Library (libc.a)

Syntax

#include <unistd.h>

char *ttyname( FileDescriptor)
int FileDescriptor;

int isatty(FileDescriptor)
int FileDescriptor;

Description

Attention: Do not use the ttyname subroutine in a multithreaded environment.

The ttyname subroutine gets the path name of a terminal.

The isatty subroutine determines if the file descriptor specified by the FileDescriptor parameter is associated with a terminal.

The isatty subroutine does not necessarily indicate that a person is available for interaction, since nonterminal devices may be connected to the communications line.

Parameters

Return Values

The ttyname subroutine returns a pointer to a string containing the null-terminated path name of the terminal device associated with the file descriptor specified by the FileDescriptor parameter. A null pointer is returned and the errno global variable is set to indicate the error if the file descriptor does not describe a terminal device in the /dev directory.

The return value of the ttyname subroutine may point to static data whose content is overwritten by each call.

If the specified file descriptor is associated with a terminal, the isatty subroutine returns a value of 1. If the file descriptor is not associated with a terminal, a value of 0 is returned and the errno global variable is set to indicate the error.

Error Codes

The ttyname and isatty subroutines are unsuccessful if one of the following is true:

Implementation Specifics

These subroutines are part of Base Operating System (BOS) Runtime.

Files

Related Information

The ttyslot (ttyslot Subroutine) subroutine.

The Input and Output Handling Programmer's Overview in AIX 5L Version 5.1 General Programming Concepts: Writing and Debugging Programs.