End-of-Transmission character

In telecommunication, an End-of-Transmission character (EOT) is a transmission control character. Its intended use is to indicate the conclusion of a transmission that may have included one or more texts and any associated message headings. An EOT is often used to initiate other functions, such as releasing circuits, disconnecting terminals, or placing receive terminals in a standby condition. Its most common use today is to cause a Unix terminal driver to signal and thus exit programs that are awaiting input. In ASCII and Unicode, the character is encoded at . It can be referred to as , in caret notation. Unicode provides the character for when EOT needs to be displayed graphically. In addition, can also be used as a graphic representation of EOT; it is defined in Unicode as "symbol for End of Transmission". The EOT character in Unix is different from the Control-Z in DOS. The DOS Control-Z byte is actually sent and/or placed in files to indicate where the text ends. In contrast, the Control-D causes the Unix terminal driver to signal the condition, which is not a character, while the byte has no special meaning if actually read or written from a file or terminal. In Unix, the end-of-file character (by default EOT) causes the terminal driver to make available all characters in its input buffer immediately; normally the driver would collect characters until it sees an end-of-line character. If the input buffer is empty (because no characters have been typed since the last end-of-line or end-of-file), a program reading from the terminal reads a count of zero bytes. In Unix, such a condition is understood as having reached the end of the file. This can be demonstrated with the program on Unix-like operating systems such as Linux: Run the command with no arguments, so it accepts its input from the keyboard and prints output to the screen. Type a few characters without pressing , then type . The characters typed to that point are sent to cat, which then writes them to the screen.