Call a C program from php and read program output

Question

Could some one explain me how to run a C program from a php script and store console output of the C program to a php variable?

My program prints an integer value on the console using C printf() function. I want to read this value and store it in a php variable.
I am using linux. I tried exec but it doesn't display the variable value once echoed to the page

This the code snippet I am using.

exec("Release/matchface image1.jpg image2.jpg", $output);
while( list(,$row) = each($output) ) {
  echo $row. "<br />";
}

Community · Accepted Answer · 2023-11-17 19:42:58Z

13

You'll want to use the shell_exec() function (quoting) :

Execute command via shell and return the complete output as a string

Which means something that will look like this :

$output = shell_exec('/path/to/your/program');

Or, you could use the [**`backtick operator`**][2] -- which would do exactly the same thing *(quoting)* :

PHP will attempt to execute the contents of the backticks as a shell command; the output will be returned

And, in code :

$output = `/path/to/your/program`;

edited Nov 17, 2023 at 19:42

CommunityBot

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answered Apr 5, 2011 at 17:27

Pascal MARTIN

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6 Comments

Niroshan Over a year ago

this doesn't print anything on browser.

Pascal MARTIN Over a year ago

Even if you use echo $output; ? Are you sure your C program is echoing on stdout ?

Niroshan Over a year ago

Yep it does. I ran it in terminal using exact parameter parsed to exec() and it prints an integer.

Lightness Races in Orbit Over a year ago

@Niroshan: That doesn't necessarily mean it's printing on STDOUT. It could be printing on STDERR. And make sure your path is correct. Don't forget that the environment is different.

Leo Over a year ago

I know it's not the case in this example, but just a word of caution: if you ever take arguments from a user in the shell_exec(), you should strongly consider using the escapeshellcmd() function (e.g. shell_exec('ls -latr ' . escapeshellcmd($arg);) otherwise, if the user-entered field arg is '; rm *.*' they'll remove all your files, or inject any code they wish...

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