escapeshellcmd() escapes any characters in a string that might be used to trick a shell command into executing arbitrary commands. This function should be used to make sure that any data coming from user input is escaped before this data is passed to the exec() or system() functions, or to the backtick operator. A standard use would be:
<?php
$e = escapeshellcmd($userinput);
// here we don't care if $e has spaces
system("echo $e");
$f = escapeshellcmd($filename);
// and here we do, so we use quotes
system("touch \"/tmp/$f\"; ls -l \"/tmp/$f\"");
?> |
See also escapeshellarg(), exec(), popen(), system(), and the backtick operator.