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Input from TTY is strange #2504
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This is seems to be a regression that could have been introduced by 8cee8f5 (didn't do
git bisect, just layman's bisecting). @nodejs/platform-windows ?From what I can tell it has to do with
process.stdintaking so long to initialize when first accessed.For example, if you use:
process.stdin; console.log('ready'); var fs = require('fs'), buffer = new Buffer(1024), fd = process.platform === 'win32' ? process.stdin.fd : fs.openSync('/dev/tty', 'r'), readSize = fs.readSync(fd, buffer, 0, 1024); console.log('INPUT: ' + buffer.toString('utf8', 0, readSize));
Then the first line will get read as expected if you type it after
readyis displayed.Thank you, but... I tried your solution, and it did not read first line.
ready foo bar INPUT: bar
I tried your sample code on Windows 8.1 64bit with iojs v2.3.1, v2.3.2 and v3.1.0. Of course v2.3.1 works fine.
Also I tried
0instead ofprocess.stdin.fd. It works fine before accessing toprocess.stdin, but it doesn't read first line after accessing toprocess.stdin.For example, this code doesn't read first line:
var fs = require('fs'), buffer = new Buffer(1024), fd = process.platform === 'win32' ? process.stdin.fd : fs.openSync('/dev/tty', 'r'), //readSize = fs.readSync(fd, buffer, 0, 1024); readSize = fs.readSync(0, buffer, 0, 1024); console.log('INPUT: ' + buffer.toString('utf8', 0, readSize));
Yes I know that
fdis meaningless now, then this works fine:var fs = require('fs'), buffer = new Buffer(1024), //fd = process.platform === 'win32' ? process.stdin.fd : fs.openSync('/dev/tty', 'r'), //readSize = fs.readSync(fd, buffer, 0, 1024); readSize = fs.readSync(0, buffer, 0, 1024); console.log('INPUT: ' + buffer.toString('utf8', 0, readSize));
But
process.stdinmight be used at a place I don't know. (e.g. other packages)
That is, this code doesn't read first line:process.stdin; var fs = require('fs'), buffer = new Buffer(1024), readSize = fs.readSync(0, buffer, 0, 1024); console.log('INPUT: ' + buffer.toString('utf8', 0, readSize));
I think that a point is that the programers don't know that
process.stdinmakes problem, and it should not so. (this is not designed behavior, right?)@nodejs/streams : is it legal to use fs.readSync to read from process.stdin, which in this case is not a file?
so is the issue that references to process.stdin initiate the readable stream, which does some buffering and that buffering prevents somebody from reading stdin like it was a file?
It seems that programmers use
read/readSyncwith STDIN to get the user's input easily instead ofprocess.stdin.on('data'). Also my module readlineSync triesreadSync.
https://www.google.com/search?q=nodejs+read+from+stdinThis problem occurs when it reads from TTY. It seems no problem when it reads from the file or pipe. (e.g.
script < file,echo foo | scriptetc)It seems that the Readline module also is affected by this problem.
For example:
var readline = require('readline').createInterface({ input: process.stdin, output: process.stdout }); readline.question('> ', function(answer) { console.log('INPUT: ', answer); readline.close(); });
In io.js v2.3.1-, no problem:
> foo INPUT: fooIn io.js v2.3.2+, strange second line is shown:
> foo foo INPUT: fooNode.js v4.2.1 also returns same result:
> foo foo INPUT: fooIt seems that REPL also is affected by this problem.
I typed a first
1and pushed the Enter key.
In io.js v2.3.1-, no problem:E:\test>node > 1 1 >In io.js v2.3.2+, strange second
1is shown:E:\test>node > 1 1 1 >Node.js v4.2.1 also returns same result:
E:\test>node > 1 1 1 >- changed the title
[-]fs.readSync of v2.3.2+ can't read first line from STDIN[/-][+]Input from STDIN is strange[/+]on Oct 17, 2015 - changed the title
[-]Input from STDIN is strange[/-][+]Input from TTY is strange[/+]on Oct 17, 2015 It seems that only the first line of both readline module and REPL is strange, like readSync.
#2504 (comment)For example:
> foo foo INPUT: foo > bar INPUT: barE:\test>node > 1 1 1 > 2 2 >6 remaining items
Filed #3490 for the revert. I could use some assistence with a regression test for this.
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on Nov 7, 2015 - added 2 commits that reference this issue
on Nov 10, 2015 - added a commit that references this issue
on Dec 4, 2015 - added 2 commits that reference this issue
on Dec 17, 2015 Related to #5384
This issue came again, and it was fixed in v6.2.0.
Then, the versions of Node.js that have the problem:- VERSION >= 2.3.2 && VERSION < 4.2.4
- VERSION >= 5.0.0 && VERSION < 5.1.0
- VERSION >= 5.6.0 && VERSION < 6.2.0
Easy check:
var verNum = (function(ver) { var nums = ver.replace(/^\D+/, '').split('.'); var verNum = 0; if ((nums[0] = +nums[0])) { verNum += nums[0] * 10000; } if ((nums[1] = +nums[1])) { verNum += nums[1] * 100; } if ((nums[2] = +nums[2])) { verNum += nums[2]; } return verNum; })(process.version), hasProblem = verNum >= 20302 && verNum < 40204 || verNum >= 50000 && verNum < 50100 || verNum >= 50600 && verNum < 60200; if (hasProblem) { console.log('TTY has problem.'); } else { console.log('TTY has NO problem.'); }
- added a commit that references this issue
on Jul 27, 2026
I tried read from STDIN by
fs.readSyncthat is givenprocess.stdin.fd.For example:
In v2.3.1-, no problem:
In v2.3.2+, first line is ignored, and second line is accepted:
This problem occurs in only Windows + iojs v2.3.2+.
I don't use
process.stdin.fdin non-Win becausefs.readSynccan't read it.Therefore,
process.stdinof v2.3.2+ might have problem. (notfs.readSync)