unable to execute shell_exec() with variable

Question

I'm trying to run shell_exec() with variable passed with AJAX from client.

This code causes error (input file doesn't exist!):

$searched_image = escapeshellarg("/home/XXX/XXX/XXX/XXX/XXX/sp_dom1.jpg");

$old_path = getcwd();

chdir('../elevation/source_code/altitudes_system/');

$altitudes_system_result = shell_exec('./predict_altitude.sh -i "{$searched_image}" -p basic -o 0');

chdir($old_path);

But when I replace "{$searched_image}" in shell_exec(...) with /home/XXX/XXX/XXX/XXX/XXX/sp_dom1.jpg code works well:

$old_path = getcwd();

chdir('../elevation/source_code/altitudes_system/');

$altitudes_system_result = shell_exec('./predict_altitude.sh -i /home/XXX/XXX/XXX/XXX/XXX/sp_dom1.jpg -p basic -o 0');

chdir($old_path);

Don't you have any idea why it works like this?

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Answer 1

You write:

'./predict_altitude.sh -i "{$searched_image}" -p basic -o 0'

Inside single-quoted strings variables are not evaluated.

You can use this, instead:

"./predict_altitude.sh -i '{$searched_image}' -p basic -o 0"

Or - to avoid unpredictable evaluations - this:

$cmd = './predict_altitude.sh -i \''.$searched_image.'\' -p basic -o 0';
shell_exec( $cmd );

unable to execute shell_exec() with variable

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