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-descriptorSpecifies an open file descriptor. 

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

lenSpecifies 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)