bash - what is EOF in cygwin in windows 10

Question

I used to run cygwin on win8.1, and while giving inputs to a program CTRL-Z used to denote EOF. Today I installed cygwin on win10, and ran "a.out". After typing in the input data, when I press CTRL-Z I get the message "Suspended" and I get back the shell prompt. I tried this with bash and csh, same result. CTRL-D also does not work, it is killing the shell.

Just to confirm that it is only this problem and nothing else, I created a new input.txt file, and entered the relevant input data in it, and ran "a.out < input.txt", and it worked fine. So the problem is only in defining EOF for STDIN.

How to solve this problem?

Note: I am closing this question, and put in more details in a new question reading till EOF in java on cygwin on windows-10

Answer 1

On Unix-like systems, including Cygwin, Ctrl-D is (by default) configured to trigger an end-of-file condition when reading from a tty (terminal/keyboard). It's possible to change this using the stty command, but it looks like you haven't done that (and you almost certainly shouldn't).

If you enter Ctrl-D while running your program that reads from standard input, that will likely terminate your program, depending on how it responds to reaching the end of its input.

Ctrl-Z sends a signal that suspends your current program (some programs, such as interactive shells, are able to handle or ignore that signal). (Windows uses Ctrl-Z to trigger end-of-file.)

The behavior you describe indicates that you're typing Ctrl-D at a shell prompt. This gives the shell, not your program, and end-of-file condition. The shell response to this by terminating (by default; you can use set -o ignoreeof to tell the shell to ignore it).

If you type Ctrl-D while running your program, it should correctly trigger and end-of-file condition and cause your program to terminate.

UPDATE: Normally you should type Ctrl-D either before any other input (resulting in the program receiving no input at all), or immediately after typing Return. To trigger end-of-file in the middle of a line, you'd have to type Ctrl-D twice. (This is usually not a great idea, since it results in the program seeing a partial line with no terminating newline character.)