tty
The tty utility shall write to the standard output the name of the terminal that is open as standard input. The name that is used shall be equivalent to the string that would be returned by the ttyname() function defined in the System Interfaces volume of IEEE Std 1003.1-2001.
The tty utility shall conform to the Base Definitions volume of IEEE Std 1003.1-2001, Section 12.2, Utility Syntax Guidelines.
None.
While no input is read from standard input, standard input shall be examined to determine whether or not it is a terminal, and, if so, to determine the name of the terminal.
None.
The following environment variables shall affect the execution of tty:
Default.
If standard input is a terminal device, a pathname of the terminal as specified by the ttyname() function defined in the System Interfaces volume of IEEE Std 1003.1-2001 shall be written in the following format:
"%s\n", <terminal name>
Otherwise, a message shall be written indicating that standard input is not connected to a terminal. In the POSIX locale, the tty utility shall use the format:
"not a tty\n"
The standard error shall be used only for diagnostic messages.
None.
None.
The following exit values shall be returned:
Default.
The following sections are informative.
This utility checks the status of the file open as standard input against that of an implementation-defined set of files. It is possible that no match can be found, or that the match found need not be the same file as that which was opened for standard input (although they are the same device).
None.
None.
None.
The System Interfaces volume of IEEE Std 1003.1-2001, isatty(), ttyname()