fopen() binds a named resource, specified by filename, to a stream. If filename is of the form "scheme://...", it is assumed to be a URL and PHP will search for a protocol handler (also known as a wrapper) for that scheme. If no wrappers for that protocol are registered, PHP will emit a notice to help you track potential problems in your script and then continue as though filename specifies a regular file.
If PHP has decided that filename specifies a local file, then it will try to open a stream on that file. The file must be accessible to PHP, so you need to ensure that the file access permissions allow this access. If you have enabled safe mode, or open_basedir further restrictions may apply.
If PHP has decided that filename specifies a registered protocol, and that protocol is registered as a network URL, PHP will check to make sure that allow_url_fopen is enabled. If it is switched off, PHP will emit a warning and the fopen call will fail.
Note: The list of supported protocols can be found in Appendix L. Some protocols (also referred to as wrappers) support context and/or php.ini options. Refer to the specific page for the protocol in use for a list of options which can be set. ( i.e. php.ini value user_agent used by the http wrapper) For a description of contexts and the zcontext parameter , refer to Reference CXI, Stream Functions.
Note: Context support was added with PHP 5.0.0.
The mode parameter specifies the type of access you require to the stream. It may be any of the following:
Table 1. A list of possible modes for fopen() using mode
| mode | Description |
|---|---|
| 'r' | Open for reading only; place the file pointer at the beginning of the file. |
| 'r+' | Open for reading and writing; place the file pointer at the beginning of the file. |
| 'w' | Open for writing only; place the file pointer at the beginning of the file and truncate the file to zero length. If the file does not exist, attempt to create it. |
| 'w+' | Open for reading and writing; place the file pointer at the beginning of the file and truncate the file to zero length. If the file does not exist, attempt to create it. |
| 'a' | Open for writing only; place the file pointer at the end of the file. If the file does not exist, attempt to create it. |
| 'a+' | Open for reading and writing; place the file pointer at the end of the file. If the file does not exist, attempt to create it. |
| 'x' | Create and open for writing only; place the file pointer at the beginning of the file. If the file already exists, the fopen() call will fail by returning FALSE and generating an error of level E_WARNING. If the file does not exist, attempt to create it. This is equivalent to specifying O_EXCL|O_CREAT flags for the underlying open(2) system call. This option is supported in PHP 4.3.2 and later, and only works for local files. |
| 'x+' | Create and open for reading and writing; place the file pointer at the beginning of the file. If the file already exists, the fopen() call will fail by returning FALSE and generating an error of level E_WARNING. If the file does not exist, attempt to create it. This is equivalent to specifying O_EXCL|O_CREAT flags for the underlying open(2) system call. This option is supported in PHP 4.3.2 and later, and only works for local files. |
Note: Different operating system families have different line-ending conventions. When you write a text file and want to insert a line break, you need to use the correct line-ending character(s) for your operating system. Unix based systems use \n as the line ending character, Windows based systems use \r\n as the line ending characters and Macintosh based systems use \r as the line ending character.
If you use the wrong line ending characters when writing your files, you might find that other applications that open those files will "look funny".
Windows offers a text-mode translation flag ('t') which will transparently translate \n to \r\n when working with the file. In contrast, you can also use 'b' to force binary mode, which will not translate your data. To use these flags, specify either 'b' or 't' as the last character of the mode parameter.
The default translation mode depends on the SAPI and version of PHP that you are using, so you are encouraged to always specify the appropriate flag for portability reasons. You should use the 't' mode if you are working with plain-text files and you use \n to delimit your line endings in your script, but expect your files to be readable with applications such as notepad. You should use the 'b' in all other cases.
If you do not specify the 'b' flag when working with binary files, you may experience strange problems with your data, including broken image files and strange problems with \r\n characters.
For portability, it is strongly recommended that you always use the 'b' flag when opening files with fopen().
Again, for portability, it is also strongly recommended that you re-write code that uses or relies upon the 't' mode so that it uses the correct line endings and 'b' mode instead.
As of PHP 4.3.2, the default mode is set to binary for all platforms that distinguish between binary and text mode. If you are having problems with your scripts after upgrading, try using the 't' flag as a workaround until you have made your script more portable as mentioned above.
The optional third use_include_path parameter can be set to '1' or TRUE if you want to search for the file in the include_path, too.
If the open fails, the function returns FALSE and an error of level E_WARNING is generated. You may use @ to suppress this warning.
If you are experiencing problems with reading and writing to files and you're using the server module version of PHP, remember to make sure that the files and directories you're using are accessible to the server process.
On the Windows platform, be careful to escape any backslashes used in the path to the file, or use forward slashes.
| Warning |
When using SSL, Microsoft IIS will violate the protocol by closing the connection without sending a close_notify indicator. PHP will report this as "SSL: Fatal Protocol Error" when you reach the end of the data. To workaround this, you should lower your error_reporting level not to include warnings. PHP 4.3.7 and higher can detect buggy IIS server software when you open the stream using the https:// wrapper and will suppress the warning for you. If you are using fsockopen() to create an ssl:// socket, you are responsible for detecting and suppressing the warning yourself. |
Note: When safe mode is enabled, PHP checks whether the directory in which you are about to operate has the same UID (owner) as the script that is being executed.
See also Appendix L, fclose(), fgets(), fread(), fwrite(), fsockopen(), file(), file_exists(), is_readable(), stream_set_timeout(), and popen().