PHP CLI setting cooked terminal mode

./myScript | less

Since less is an interactive program it puts the terminal into 'raw' mode so
that it can read characters one at a time. However, when I do the above I find
that the commands that I type to less are echoed back to me and not acted on
until I type <RETURN>. This is not as it should be.

If I run the script under strace I see:

ioctl(0, SNDCTL_TMR_TIMEBASE or TCGETS, {B38400 opost isig icanon echo ...}) = 0
ioctl(0, SNDCTL_TMR_STOP or TCSETSW, {B38400 opost isig icanon echo ...}) = 0

What is happening is that PHP is putting the terminal into cooked mode.

Are you sure it is PHP that's doing this? There are basically no calls
to ioctl() (or tcsetattr() for that matter) outside of ext/ at all.

• Martin

I've seen something similar on Debian; it might be a patch that
your distro is shipping on top of PHP.

Edward

Excerpts from Alain Williams's message of Sat Sep 14 04:45:41 -0700 2013:

Hi,

I am running a PHP script at the command line and piping the output through less:

./myScript | less

Since less is an interactive program it puts the terminal into 'raw' mode so
that it can read characters one at a time. However, when I do the above I find
that the commands that I type to less are echoed back to me and not acted on
until I type <RETURN>. This is not as it should be.

The sript is not doing anything clever, just generating 100 lines:
for($i = 0; $i < 100; $i++)
echo "i=$i\n";

If I run the script under strace I see:

ioctl(0, SNDCTL_TMR_TIMEBASE or TCGETS, {B38400 opost isig icanon echo ...}) = 0
ioctl(0, SNDCTL_TMR_STOP or TCSETSW, {B38400 opost isig icanon echo ...}) = 0

What is happening is that PHP is putting the terminal into cooked mode.

I can get it to not do this by connecting stdin to /dev/null:

./myScript < /dev/null | less

another way of getting it to work is (and this shows that it really is PHP that
is messing the tty modes):

./myScript < /dev/null | (sleep 10; less)

However: PHP should not set the terminal to cooked mode in the first place.

Is there any way in which I can get PHP to not do this ?

TIA

I am running PHP 5.3.3 on CentOS 6.

I posted this to php-general@lists.php.net a few days ago, but did not get a
sensible reply.

One could use ltrace -l to trace library calls.

On my laptop (Debian) :

ltrace -l /usr/lib/x86_64-linux-gnu/libedit.so.2 php -a

using_history(1, 38, 0x250000000f, 712, 0x1087900) = 0
Interactive shell

Thanks - that helps. That is called in PHP_MINIT_FUNCTION(readline)
in ./ext/readline/readline.c

I have modified the initialisation function as below, using isatty() on STDIN &
STDOUT. This will stop readline being initialised if it is not being used
interactively.

I have not even tried to compile this, I don't understand enough about how it
all hangs together to know if it will work - one concern is that if the PHP
script tries to read from STDIN it might all fail, all of the readline stuff
should probably return FALSE if it has not initialised.

PHP_MINIT_FUNCTION(readline)
{
/* Do not start readline if not connected to a terminal on both STDIN & STDOUT */
if( !isatty(0) || !isatty(1))
return SUCCESS;

    using_history();
    return PHP_MINIT(cli_readline)(INIT_FUNC_ARGS_PASSTHRU);

}

BTW: this code has changed between php-5.5.3 & php-5.3.3. The version that I
have been using is PHP 5.3.3. The code above is from PHP 5.5.3.

--
Alain Williams
Linux/GNU Consultant - Mail systems, Web sites, Networking, Programmer, IT Lecturer.
+44 (0) 787 668 0256 http://www.phcomp.co.uk/
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