How to process stdin to stdout in php?

Question

I'm trying to write a simple php script to take in data from stdin, process it, then write it to stdout. I know that PHP is probably not the best language for this kind of thing, but there is existing functionality that I need.

I've tried

<?php
$file = file_get_contents("php://stdin", "r");
echo $file;
?>

but it doesn't work. I'm invoking it like this: echo -e "\ndata\n" | php script.php | cat. and get no error messages. The script I'm trying to build will actually be part of a larger pipeline.

Any clues as to why this is not working?

PS: I'm not very experienced with PHP.

Solution 1

If you are piping, you will want to buffer the input, instead of processing it all at once, just go one line at a time as is standard for *nix tools.

The SheBang on top of the file allows you to execute the file directly, instead of having to call php in the command line.

Save the following to test.php and run

cat test.php | ./test.php

to see the results.

#!php
<?php
$handle = fopen('php://stdin', 'r');
$count = 0;
while(!feof($handle)) {
    $buffer = fgets($handle);
    echo $count++, ": ", $buffer;
}
fclose($handle);

Solution 2

To place a php-script in a pipe you can use:

xargs -d "\n" ./mysrcipt.php --foo

With many lines/args the ./myscript.php will be called a couple times, but always with --foo.

e.g.:

./myscript.php:
#!/bin/php
<?php
foreach($args as $key => $value){
 echo "\n".$key.":".$value;
}
?>
cat -n1000 /path/file | xargs -d "\n" ./myscript.php --foo | less

will call the script two times with echo to stdout/less:

0:./myscript
1:--foo
2:[file-line1]
3:[file-line2]
...
800:[file-line799]
0:./myscript
1:--foo
2:[file-line800]
...

source

Comments

[brice]

thanks compie. I can't afford to have the initial stream bisected as xargs would do. The php script has to have the entire thing. Is there really no way of using php in a pipe without resorting to stuff like this?

[CMCDragonkai]

What if there is no STDIN available at the time of execution? Wouldn't this make the script hang?

[Kamafeather]

I just assume that the STDIN is always available in PHP, but its buffer will be empty (or, better, just including EOF).