The program below simply reads a string and outputs it. When I run this on cmd, the program doesn't print out the string. It keeps reading inputs until I terminate with Ctrl+C. How do I tell the program when my input string is over, so it can print the output?
var concat=require('concat-stream');
var str=[];
process.stdin.pipe(concat(function(buff){
console.log(buff.toString());
}));
concat-stream is waiting to receive a finish event. In your example that will happen when you close stdin. If you’re running this in a shell you can close stdin by pressing Ctrl+D. If you’re piping something to your process, make sure it closes its stdout when it’s done.
If you’re trying to make your script interactive in the shell, try split:
process.stdin
.pipe(require('split')())
.on('data', function (line) {
console.log('got “%s”', line);
});
Obviously the answer by Todd Yandell is the right one, and I have already upvoted it, but I wanted to add that besides split, you may also consider the use of through which creates a sort of transformer and it would also work in a interactive way, since it is not an aggregation pipe.
Like this example in which everything you write in the standard input gets uppercased in standard output interactively:
var through = require('through');
function write(buffer){
var text = buffer.toString();
this.queue(text.toUpperCase());
}
function end(){
this.queue(null);
}
var transform = through(write, end);
process.stdin.pipe(transform).pipe(process.stdout);
You may even combine it with split by doing:
process.stdin
.pipe(split())
.pipe(transform)
.pipe(process.stdout);