Ref/xattr-Phpdoc专题
xattr_get
Get an extended attribute
说明
string <span
class="methodname">xattr_get ( <span
class="type">string $filename , <span
class="methodparam">string $name [,
int $flags<span
class="initializer"> = 0 ] )
This function gets the value of an extended attribute of a file.
扩展的属性有两种 不同的命名空间：user 和 root。user
命名空间对所有用户均有效，而 root 命名空间仅对拥有 root 权限的用户有效。
xattr 默认在 user 命名空间上操作，但可使用 flags 参数进行更改。
参数
filename
The file from which we get the attribute.
name
The name of the attribute.
flags
| | |
|------------------------|----------------------------------------------------------------------|
| XATTR_DONTFOLLOW | Do not follow the symbolic link but operate on symbolic link itself. |
| XATTR_ROOT | Set attribute in root (trusted) namespace. Requires root privileges. |
返回值
Returns a string containing the value or false if the attribute
doesn't exist.
范例
示例 #1 Checks if system administrator has signed the file
<?php
$file = '/usr/local/sbin/some_binary';
$signature = xattr_get($file, 'Root signature', XATTR_ROOT);
/* ... check if $signature is valid ... */
?>参见
- xattr_list
- xattr_set
- xattr_remove
xattr_list
Get a list of extended attributes
说明
array <span
class="methodname">xattr_list ( <span
class="type">string $filename [, <span
class="methodparam">int $flags<span
class="initializer"> = 0 ] )
This functions gets a list of names of extended attributes of a file.
扩展的属性有两种 不同的命名空间：user 和 root。user
命名空间对所有用户均有效，而 root 命名空间仅对拥有 root 权限的用户有效。
xattr 默认在 user 命名空间上操作，但可使用 flags 参数进行更改。
参数
filename
The path of the file.
flags
| | |
|------------------------|----------------------------------------------------------------------|
| XATTR_DONTFOLLOW | Do not follow the symbolic link but operate on symbolic link itself. |
| XATTR_ROOT | Set attribute in root (trusted) namespace. Requires root privileges. |
返回值
This function returns an array with names of extended attributes.
范例
示例 #1 Prints names of all extended attributes of file
<?php
$file = 'some_file';
$root_attributes = xattr_list($file, XATTR_ROOT);
$user_attributes = xattr_list($file);
echo "Root attributes: \n";
foreach ($root_attributes as $attr_name) {
printf("%s\n", $attr_name);
}
echo "\n User attributes: \n";
foreach ($attributes as $attr_name) {
printf("%s\n", $attr_name);
}
?>参见
- xattr_get
xattr_remove
Remove an extended attribute
说明
bool <span
class="methodname">xattr_remove ( <span
class="methodparam">string $filename
, string
$name [, <span
class="type">int $flags =
0 ] )
This function removes an extended attribute of a file.
扩展的属性有两种 不同的命名空间：user 和 root。user
命名空间对所有用户均有效，而 root 命名空间仅对拥有 root 权限的用户有效。
xattr 默认在 user 命名空间上操作，但可使用 flags 参数进行更改。
参数
filename
The file from which we remove the attribute.
name
The name of the attribute to remove.
flags
| | |
|------------------------|----------------------------------------------------------------------|
| XATTR_DONTFOLLOW | Do not follow the symbolic link but operate on symbolic link itself. |
| XATTR_ROOT | Set attribute in root (trusted) namespace. Requires root privileges. |
返回值
成功时返回 true， 或者在失败时返回 false。
范例
示例 #1 Removes all extended attributes of a file
<?php
$file = 'some_file';
$attributes = xattr_list($file);
foreach ($attributes as $attr_name) {
xattr_remove($file, $attr_name);
}
?>参见
- xattr_list
- xattr_set
- xattr_get
xattr_set
Set an extended attribute
说明
bool <span
class="methodname">xattr_set ( <span
class="type">string $filename , <span
class="methodparam">string $name ,
string
$value [, <span
class="type">int $flags =
0 ] )
This function sets the value of an extended attribute of a file.
扩展的属性有两种 不同的命名空间：user 和 root。user
命名空间对所有用户均有效，而 root 命名空间仅对拥有 root 权限的用户有效。
xattr 默认在 user 命名空间上操作，但可使用 flags 参数进行更改。
参数
filename
The file in which we set the attribute.
name
The name of the extended attribute. This attribute will be created if it
doesn't exist or replaced otherwise. You can change this behaviour by
using the flags parameter.
value
The value of the attribute.
flags
| | |
|------------------------|----------------------------------------------------------------------|
| XATTR_CREATE | Function will fail if extended attribute already exists. |
| XATTR_REPLACE | Function will fail if extended attribute doesn't exist. |
| XATTR_DONTFOLLOW | Do not follow the symbolic link but operate on symbolic link itself. |
| XATTR_ROOT | Set attribute in root (trusted) namespace. Requires root privileges. |
返回值
成功时返回 true， 或者在失败时返回 false。
范例
示例 #1 Sets extended attributes on .wav file
<?php
$file = 'my_favourite_song.wav';
xattr_set($file, 'Artist', 'Someone');
xattr_set($file, 'My ranking', 'Good');
xattr_set($file, 'Listen count', '34');
/* ... other code ... */
printf("You've played this song %d times", xattr_get($file, 'Listen count'));
?>参见
- xattr_get
- xattr_remove
xattr_supported
Check if filesystem supports extended attributes
说明
bool <span
class="methodname">xattr_supported ( <span
class="methodparam">string $filename
[, int
$flags = 0 ] )
This functions checks if the filesystem holding the given file supports extended attributes. Read access to the file is required.
参数
filename
The path of the tested file.
flags
| | |
|------------------------|----------------------------------------------------------------------|
| XATTR_DONTFOLLOW | Do not follow the symbolic link but operate on symbolic link itself. |
返回值
This function returns true if filesystem supports extended
attributes, false if it doesn't and null if it can't be
determined (for example wrong path or lack of permissions to file).
范例
示例 #1 xattr_supported example
The following code checks if we can use extended attributes.
<?php
$file = 'some_file';
if (xattr_supported($file)) {
/* ... make use of some xattr_* functions ... */
}
?>参见
- xattr_get
- xattr_list
目录
- xattr_get — Get an extended attribute
- xattr_list — Get a list of extended attributes
- xattr_remove — Remove an extended attribute
- xattr_set — Set an extended attribute
- xattr_supported — Check if filesystem supports extended attributes