PHP Delete files with unlink function permissions to judge _php Tutorial

unlink function in PHP is to delete the file, but we can determine whether the file has delete permissions, let me give you a brief introduction to the Unlink function usage and permission to judge.

Unlink ($file)

Example 1

The code is as follows	Copy Code
Unlink ($somefile) Or Die ("Cannot delete file.") ?>

Sometimes permissions problems occur, write permissions to files, but cannot be deleted.

The reason is simple, delete the file is not to modify the file, but to modify the directory, you need to write to the directory where the file

The is_readable () function is applied to determine whether a file has Read permissions, and the Is_writable () function is used to determine whether the file has write permissions. The is_readable () function, which determines whether the specified file is readable, has the following syntax:
bool Is_readable (string filename)
Returns True if the file exists and is readable. The
Is_writable () function, which determines whether the specified file is writable, has the following syntax:
bool Is_writable (string filename)
Returns True if the file exists and is writable. The parameter filename can be a directory name that allows for a writable check.
Note: PHP may only be able to access the file by running the webserver user name (typically ' nobody '). Restrictions that do not count toward Safe mode. The judgment of the file permissions is the premise of the operation of the file, especially in the execution of the file read, write, rename, and so on, if the file does not have the permission to read, write, then these operations are meaningless. The
Design process
(1) creates a index.php file.
(2) Add the form, set the text box, submit the specified file, set the file field, submit the data written to the file, set the Submit button, and use the Post method to submit the data to this page. The
(3) obtains the file path and file contents of the form submission through the $_post[] method, and encodes the obtained data through the Iconv () function. First, determine whether the specified file exists. It then determines whether the specified file has write permissions, and if so, writes the contents of the file submitted by the form to the file. Finally, close the open file and give a hint. The key code for index.php is as follows:

The code is as follows

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if ($_post[' file_name ']!= "" && Is_file (Iconv ("Utf-8", "gb2312", $_post[' file_name '))) {//Determine if the file exists $file _name=iconv ("Utf-8", "gb2312", $_post[' file_name ']); Encoding Conversion if (file_exists ($file _name)) { if (is_writable ($file _name)) {//Determine if the file has Write permission $FP =fopen ($file _name, "w+"); Opens the specified file if (fwrite ($fp, $file _content)) {//Perform write operation echo ""; }else{ echo ""; } Fclose ($FP); Close File }else if (is_readable ($file _name)) {//Determine if the file has Read permissions echo ""; }else{ echo ""; } }else{ echo ""; } }else{ echo ""; } ?>

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