Interactive shell using PHP

Question

Just wondering, is it possible to create an interactive shell, using PHP alone. I mean something like you have with databases, python, etc.

If it is, how?

Answer 1

Since PHP has a built-in unix only function readline() to do exactly that, here leaving the following notes.

We can use and hold the result of readline into a var.

#!/usr/bin/php
<?php
$user = readline("List dir [l] | Say hello [h] | exit [q]: ");

if ($user === "l"){ system("ls"); }

if ($user === "h"){ echo "Hello!"; }

if ($user === "q"){ exit; }

echo "\nThanks!";

Example output:

l ls result

h «hello»

q exit

ctrl+c exit.

ctrl+d with empty input, continue to the next sequence. «Thanks». $user is defined and empty, no error.

ctrl+d with some input: No action. Still waiting for input.

ctrl+m Continue and take the current input in $user.

ctrl+j Continue and take the current input in $user, same behavior as ctrl+m.

Return continue to the next sequence «Thanks». $user can stay empty, no error.

ctrl+z may be used to cancel a loop and move to the top one. $user will be unset if the var is not defined in this scope.

Depending input, we can define empty values using!empty or do more surgical testings (the readline response can be many chars).

$user can be tested with !isset if not yet asked.

There is also the built-in readline_add_history() to store the user input into an object, where values can be retrieved directly by their name (Nice for code clarity):

readline_add_history($user);
print_r(readline_list_history());
print_r(readline_user());

Very useful to build real complex stuffs!

http://php.net/manual/en/function.readline.php

Answer 2

Yes, it's possible. In order to be interactive, the program must be able to wait for and read in user input from stdin. In PHP, you can read from stdin by opening a file descriptor to 'php://stdin'. Taken from an answer to different question, here's an example of an interactive user prompt in PHP (when run from the command line, of course):

echo "Continue? (Y/N) - ";

$stdin = fopen('php://stdin', 'r');
$response = fgetc($stdin);
if ($response != 'Y') {
   echo "Aborted.\n";
   exit;
}

Of course, to get a full line of input rather than a single character, you'd need fgets() instead of fgetc(). Depending what your program/shell will do, the whole program might be structured as one big continuous loop. Hopefully that gives you an idea how to get started. If you wanted to get really fancy (CLI pseudo-GUI), you could use ncurses.