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escapeshellarg

(PHP 4 >= 4.0.3, PHP 5)

escapeshellargЭкранирует строку для того, чтобы она могла быть использована как аргумент командной строки

Описание

string escapeshellarg ( string $arg )

Функция escapeshellarg() добавляет по одной кавычке вокруг строки и добавляет кавычки/экранирует любые существующие единичные кавычки, позволяя вам передать строку непосредственно шелл-функции и рассматривать её как один безопасный аргумент. Эта функция должна быть использована для того, чтобы экранировать отдельные аргументы для шелл-функций, полученные из ввода пользователя. Шелл-функции включают exec(), system() и оператор "обратный апостроф".

Список параметров

arg

Аргумент, который будет экранирован.

Возвращаемые значения

Экранированная строка.

Примеры

Пример #1 Пример использования escapeshellarg()

<?php
system
('ls '.escapeshellarg($dir));
?>

Смотрите также

Коментарии

If escapeshellarg() returned something on a null input it would probably break more programs than it helps. Even if it's two "'s or two ''s, this function wouldn't work the way it's supposed to (that is, returning nothing). 

However, most people do not put "" into their commands but I can see where it might be useful at the same time. 
Perhaps an option in the command that would return the type of null we want. I might want the null character to be returned, someone else might want '', and someone else might want nothing at all.
2004-03-25 19:05:53
http://php5.kiev.ua/manual/ru/function.escapeshellarg.html
Автор:
Most of the comments above have misunderstood this function. It does not need to escape characters such as '$' and '`' - it uses the fact that the shell does not treat any characters as special inside single quotes (except the single quote character itself). The correct way to use this function is to call it on a variable that is intended to be passed to a command-line program as a single argument to that program - you do not call it on command-line as a whole.

The person above who comments that this function behaves badly if given the empty string as input is correct - this is a bug. It should indeed return two single quotes in this case.
2006-05-22 08:25:30
http://php5.kiev.ua/manual/ru/function.escapeshellarg.html
Under Windows, this function puts string into double-quotes, not single, and replaces %(percent sign) with a space, that's why it's impossible to pass a filename with percents in its name through this function.
2007-04-28 07:09:38
http://php5.kiev.ua/manual/ru/function.escapeshellarg.html
Автор:
The reason why % are replaced with space on windows is that it is impossible in cmd.exe to escape or quote them so that environment variables are not expanded.  If for instance %path% is in your argument it will always be expanded, so the only safe thing to do is to replace % with something else.

Alternatively, you could wipe the environment before making the call to exec(), but that has its side-effects.
2008-07-30 08:02:14
http://php5.kiev.ua/manual/ru/function.escapeshellarg.html
If escapeshellarg() function removes your accents (like á, a with an 'accute') from the given string, ensure your LC_ALL variable is correct. If using it via web, you need to restart Apache or the corresponding web server after setting LC_ALL with a export LC_ALL=es_ES.utf8 (for example) from your shell.
2009-01-20 06:12:04
http://php5.kiev.ua/manual/ru/function.escapeshellarg.html
When running a string of LaTeX code containing hyphens through as an argument to pdflatex escaped using this command, it will result in failure.
2009-06-26 09:51:09
http://php5.kiev.ua/manual/ru/function.escapeshellarg.html
The comment from 'rmays at castlecomm dot com' is incorrect: single quotes cannot be backslash-escaped inside a single-quoted string when constructing a shell argument. The output from this function is in fact correct. It drops out of the single-quoted string, includes a literal single quote with a backslash-escape, then resumes the single-quoted string. Observe:

[shellarg.php]
<?php

system
("echo ' single quote\'d '");
system("echo ' single quote'\''d '");
?>

$ php shellarg.php 
sh: -c: line 0: unexpected EOF while looking for matching `''
sh: -c: line 1: syntax error: unexpected end of file
 single quote'd
2009-10-12 13:53:57
http://php5.kiev.ua/manual/ru/function.escapeshellarg.html
When escapeshellarg() was stripping my non-ASCII characters from a UTF-8 string, adding the following fixed the problem:

<?php
setlocale
(LC_CTYPE"en_US.UTF-8");
?>
2010-08-03 18:56:22
http://php5.kiev.ua/manual/ru/function.escapeshellarg.html
Take care if using escapeshellarg() on serialized objects. Serialized objects contain null bytes, and escapeshellarg stops on the first null byte so you will not receive the full argument. (I consider this a bug, though not sure what it should do in this case. Probably serialize shouldn't have used null bytes, but too late for that now).
The workaround I've found to pass serialized objects on the command line is to base64_encode() them first and decode on the other side.
2012-07-24 17:38:37
http://php5.kiev.ua/manual/ru/function.escapeshellarg.html
Here's a quick and dirty replacement of this function in case you need to deal with special characters.

<?php
/**
 * An ugly, non-ASCII-character safe replacement of escapeshellarg().
 */
function escapeshellarg_special($file) {
  return 
"'" str_replace("'""'\"'\"'"$file) . "'";
}
?>
2013-04-11 14:32:39
http://php5.kiev.ua/manual/ru/function.escapeshellarg.html
the best alternative to escapeshellarg() for windows i've come up with is this:
<?php
function w32escapeshellarg($s)
{ return 
'"' addcslashes($s'\\"') . '"'; }
?>
2014-04-18 22:20:14
http://php5.kiev.ua/manual/ru/function.escapeshellarg.html
Автор:
if you want empty arguments for empty input 

use the form 
   
     escapeshellarg($input)."''"

the shell will treat foo'' as foo  but empty input will become an empty argument instead of a missing one.
2018-10-30 21:49:43
http://php5.kiev.ua/manual/ru/function.escapeshellarg.html
Автор:
On Windows, this function naively strips special characters and replaces them with spaces. The resulting string is always safe for use with exec() etc, but the operation is not lossless - strings containing " or % will not be passed through to the child process correctly.

Correctly escaping shell commands on Windows is not a simple matter. Programs must consider two distinct escape mechanisms which serve different purposes:
 1) The convention used by the CommandLineToArgV() windows system function, used by the child process to interpret the command line string
 2) The convention used by cmd.exe to escape shell meta-characters (e.g. output redirection controls)

All commands should be escaped for CommandLineToArgV() - this mechanism is applied to each argument individually before it is appended to the command line string. The resulting string may be safely used with the CreateProcess() family of system functions. However...

In almost all cases when creating a child process from PHP on Windows, it is done indirectly by invoking cmd.exe - this is to enable the use of shell functionality such as I/O redirection and environment variable substitution. As a consequence, the entire command string must be further escaped for cmd.exe. If the executed command contains further indirect calls through cmd.exe, each child command must be escaped again for each level of indirection.

The following functions can be used to correctly escape strings such that they are safely passed through to a child process:

<?php

/**
 * Escape a single value in accordance with CommandLineToArgV()
 * https://docs.microsoft.com/en-us/previous-versions/17w5ykft(v=vs.85)
 */
function escape_win32_argv(string $value): string
{
    static 
$expr '(
        [\x00-\x20\x7F"] # control chars, whitespace or double quote
      | \\\\++ (?=("|$)) # backslashes followed by a quote or at the end
    )ux'
;

    if (
$value === '') {
        return 
'""';
    }

   
$quote false;
   
$replacer = function($match) use($value, &$quote) {
        switch (
$match[0][0]) { // only inspect the first byte of the match

           
case '"'// double quotes are escaped and must be quoted
               
$match[0] = '\\"';
            case 
' ': case "\t"// spaces and tabs are ok but must be quoted
               
$quote true;
                return 
$match[0];

            case 
'\\'// matching backslashes are escaped if quoted
               
return $match[0] . $match[0];

            default: throw new 
InvalidArgumentException(sprintf(
               
"Invalid byte at offset %d: 0x%02X",
               
strpos($value$match[0]), ord($match[0])
            ));
        }
    };

   
$escaped preg_replace_callback($expr$replacer, (string)$value);

    if (
$escaped === null) {
        throw 
preg_last_error() === PREG_BAD_UTF8_ERROR
           
? new InvalidArgumentException("Invalid UTF-8 string")
            : new 
Error("PCRE error: " preg_last_error());
    }

    return 
$quote // only quote when needed
       
'"' $escaped '"'
       
$value;
}

/** Escape cmd.exe metacharacters with ^ */
function escape_win32_cmd(string $value): string
{
    return 
preg_replace('([()%!^"<>&|])''^$0'$value);
}

/** Like shell_exec() but bypass cmd.exe */
function noshell_exec(string $command): string
{
    static 
$descriptors = [['pipe''r'],['pipe''w'],['pipe''w']],
           
$options = ['bypass_shell' => true];

    if (!
$proc proc_open($command$descriptors$pipesnullnull$options)) {
        throw new 
Error('Creating child process failed');
    }

   
fclose($pipes[0]);
   
$result stream_get_contents($pipes[1]);
   
fclose($pipes[1]);
   
stream_get_contents($pipes[2]);
   
fclose($pipes[2]);
   
proc_close($proc);

    return 
$result;
}

// usage

$badString 'String with "C:\\quotes\\" or malicious %OS% stuff \\';
$cmdParts = [
   
'php',
   
'-d''display_errors=1''-d''error_reporting=-1',
   
'-r''echo $argv[1];',
   
$badString // child process $argv[1] value
];

/* The typical approach - works fine on POSIX shells but totally wrong
   on Windows */
$wrong implode(' 'array_map('escapeshellarg'$cmdParts));

/* Always escape each argument individually */
$escaped implode(' 'array_map('escape_win32_argv'$cmdParts));

/* In almost all cases, escape for cmd.exe as well - the only exception is
   when using proc_open() with the bypass_shell option. cmd doesn't handle
   arguments individually, so the entire command line string can be escaped,
   no need to process arguments individually */
$cmd escape_win32_cmd($escaped);

$cmds = [
   
'escapeshellarg() - wrong' => $wrong,
   
'escape_win32_argv() - correct for bypass_shell' => $escaped,
   
'escape_win32_cmd(escape_win32_argv()) - correct everywhere else' => $cmd,
];

function 
check($original$received)
{
   
$match $original === $received '=' 'X';
    return 
"$match '$received'";
}

foreach (
$cmds as $description => $cmd) {
    echo 
"$description\n";
    echo 
" $cmd\n";
    echo 
"  original:         '$badString'\n";
    echo 
"  shell_exec():   " check($badStringshell_exec($cmd)) . "\n";
    echo 
"  noshell_exec(): " check($badStringnoshell_exec($cmd)) . "\n";
    echo 
"\n";
}
2019-03-23 04:32:07
http://php5.kiev.ua/manual/ru/function.escapeshellarg.html

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