PHP using shell_exec(bash read) works on tty but not when input is piped and has no newline

Question

TL;DR -- echo -n abc | bash -c 'read -s x && echo -n \$x' doesn't output abc.

I have a PHP CLI script which needs to read a password from stdin.

<?php

function quiet_read_stdin ()
{
    return shell_exec ("bash -c 'read -s x && echo -n \$x'");
}

print "got: ###".quiet_read_stdin ()."###\n";
?>

If I run this in a terminal and input, say, 'xyz':

$> php /tmp/foo.php
got: ###xyz###

As expected, also this works

$> echo xyz | php /tmp/foo.php
got: ###xyz###

But this doesn't.

$> echo -n xyz | php /tmp/foo.php
got: ######

This is causing problems in my script in the case that the secret key is stored in a file without a newline, equivalent to php /tmp/foo.php < keyfile.

This doesn't work (Inappropriate ioctl for device):

system ('stty -echo');
$password = trim (fgets (STDIN));
system ('stty echo');

I don't want to fudge it by inserting a newline at any stage. How can I modify quiet_read_stdin so that it works whether or not the input has a trailing newline? A Linux-only solution is fine.

You can't make "read -s" work when the input prematurely ends (before LF). So you need to look for another solution to read from STDIN with local echo disabled. — Kaii
– Kaii, Commented Nov 20, 2016 at 21:52
which OS / distribution & shell are you working on? php version? — Kaii
– Kaii, Commented Nov 20, 2016 at 22:00

Kaii · Accepted Answer · 2016-11-20 21:41:38Z

1

For me, this works:

$ cat test.php
<?php
// ignore error message
// stty: standard input: Inappropriate ioctl for device    
shell_exec('stty -echo 2>/dev/null'); 

$io = fopen("php://stdin", "r");
$password = fgets($io);
echo "foo: $password\n";

shell_exec('stty echo 2>/dev/null');

$ echo -n "xyz" | php test.php
foo: xyz

$ php test.php          # typing: abc[ENTER]
foo: abc

answered Nov 20, 2016 at 21:41

Kaii

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3 Comments

spraff Over a year ago

And as my question says, stty -echo doesn't work for me.

Kaii Over a year ago

anyway, gonna leave this here as it may help others. been using it on all my scripts and it never failed me (so far).

Kaii Over a year ago

@spraff did you try the example? When piping data to STDIN, you can safely ignore the error message as piped content is not displayed anyways. And when you call the script keyboard interactively (without piping), the stty -echo should work. For me, the error message only appears when piping content and can thus be ignored.

spraff · Accepted Answer · 2016-11-21 09:09:40Z

0

This will read a line with or without a newline and always print it with a newline

readslient.sh:

#!/bin/bash

while IFS= read -r -s LINE || [[ -n "$LINE" ]]; do
    echo $LINE
done

PHP can then

$pw = rtrim (shell_exec ("readslient.sh"));

I can't see how to make this a one-liner to shell-exec but it would be nice to not have a separate file for this.

answered Nov 21, 2016 at 9:09

spraff

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