escapeshellcmd
(PHP 4, PHP 5, PHP 7)
escapeshellcmd — Escape shell metacharacters
Description
string escapeshellcmd ( string $command )escapeshellcmd() escapes any characters in a string that might be used to trick a shell command into executing arbitrary commands. This function should be used to make sure that any data coming from user input is escaped before this data is passed to the exec() or system() functions, or to the backtick operator.
Following characters are preceded by a backslash: &#;`|*?~<>^()[]{}$_, \x0A and \xFF. ' and " are escaped only if they are not paired. In Windows, all these characters plus % and !_ are replaced by a space instead.
Parameters
command
The command that will be escaped.
Return Values
The escaped string.
Examples
Example #1 escapeshellcmd() example
<?php
//?We?allow?arbitrary?number?of?arguments?intentionally?here.
$command?=?'./configure?'.$_POST['configure_options'];
$escaped_command?=?escapeshellcmd($command);
?
system($escaped_command);
?>Warning
escapeshellcmd() should be used on the whole command string, and it still allows the attacker to pass arbitrary number of arguments. For escaping a single argument escapeshellarg() should be used instead.
Changelog
Version | Description |
|---|---|
5.6.0 | The default value for the encoding parameter was changed to be the value of the default_charset configuration option. |
5.4.43, 5.5.27, 5.6.11 | Exclamation marks are replaced by spaces. |
See Also
- escapeshellarg() - Escape a string to be used as a shell argument
- exec() - Execute an external program
- popen() - Opens process file pointer
- system() - Execute an external program and display the output
- backtick operator
← escapeshellarg
exec →
? 1997–2017 The PHP Documentation GroupLicensed under the Creative Commons Attribution License v3.0 or later.
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