linux - [Solved-5 Solutions] UTF-8 all the way through - ubuntu - red hat - debian - linux server - linux pc
Linux - Problem :
Setting up a new server, and need to support UTF-8 fully in your web application. You have tried in the past on existing servers and always seem to end up having to fall back to ISO-8859-1.
Where exactly do you need to set the encoding/charsets? First you need to configure Apache, MySQL and PHP to do this - is there some standard checklist you can follow, or perhaps troubleshoot where the mismatches occur?
This is for a new Linux server, running MySQL 5, PHP 5 and Apache 2.
Linux - Solution 1:
Data Storage:
- Specify the utf8mb4 character set on all tables and text columns in your database. This makes MySQL physically store and retrieve values encoded natively in UTF-8. Note that MySQL will implicitly use utf8mb4 encoding if a utf8mb4_* collation is specified (without any explicit character set).
- In older versions of MySQL ( 5.5.3), you'll unfortunately be forced to use simply utf8, which only supports a subset of Unicode characters.
Data Access:
- In your application code (e.g. PHP), in whatever DB access method you use, you'll need to set the connection charset to utf8mb4. This way, MySQL does no conversion from its native UTF-8 when it hands data off to your application and vice versa. Some drivers provide their own mechanism for configuring the connection character set, which both updates its own internal state and informs MySQL of the encoding to be used on the connection—this is usually the preferred approach. In PHP:
- If you're using the PDO abstraction layer with PHP ≥ 5.3.6, you can specify charset in the DSN:
- If you're using mysqli, you can call set_charset():
$dbh = new PDO('mysql:charset=utf8mb4');click below button to copy the code. By - Linux tutorial - team
$mysqli->set_charset('utf8mb4'); // object oriented style
mysqli_set_charset($link, 'utf8mb4'); // procedural styleclick below button to copy the code. By - Linux tutorial - team
mysql_set_charset.click below button to copy the code. By - Linux tutorial - team
- If the driver does not provide its own mechanism for setting the connection character set, you may have to issue a query to tell MySQL how your application expects data on the connection to be encoded: SET NAMES 'utf8mb4'.
- The same consideration regarding utf8mb4/utf8 applies as above.
Output:
- If your application transmits text to other systems, they will also need to be informed of the character encoding. With web applications, the browser must be informed of the encoding in which data is sent (through HTTP response headers or HTML metadata).
- In PHP, you can use the default_charset php.ini option, or manually issue the Content-Type MIME header yourself, which is just more work but has the same effect.
Input:
- Unfortunately, you should verify every received string as being valid UTF-8 before you try to store it or use it anywhere. PHP's mb_check_encoding() does the trick, but you have to use it religiously. There's really no way around this, as malicious clients can submit data in whatever encoding they want, and I haven't found a trick to get PHP to do this for you reliably. From my reading of the current HTML spec, the following sub-bullets are not necessary or even valid anymore for modern HTML. My understanding is that browsers will work with and submit data in the character set specified for the document. However, if you're targeting older versions of HTML (XHTML, HTML4, etc.), these points may still be useful:
- For HTML before HTML5 only: you want all data sent to you by browsers to be in UTF-8. Unfortunately, if you go by the the only way to reliably do this is add the accept-charset attribute to all your
- For HTML before HTML5 only: note that the W3C HTML spec says that clients "should" default to sending forms back to the server in whatever charset the server served, but this is apparently only a recommendation, hence the need for being explicit on every single
Other Code Considerations:
- Obviously enough, all files you'll be serving (PHP, HTML, JavaScript, etc.) should be encoded in valid UTF-8.
- PHP's built-in string operations are not by default UTF-8 safe. There are some things you can safely do with normal PHP string operations (like concatenation), but for most things you should use the equivalent mbstring function.
- To know what you're doing (read: not mess it up), you really need to know UTF-8 and how it works on the lowest possible level. Check out any of the links from utf8.com for some good resources to learn everything you need to know.
Linux - Solution 2:
Don't forget the META tag either (like this, or the HTML4 or XHTML version of it):
<meta charset="utf-8">click below button to copy the code. By - Linux tutorial - team
Database connection and Content-Type HTTP header were all set to UTF-8, and it worked fine in all other browsers, but Internet Explorer still insisted on using the "Western European" encoding.
It turned out the page was missing the META tag.
Edit:
The W3C actually has a rather large section dedicated to I18N. They have a number of articles related to this issue – describing the HTTP, (X)HTML and CSS side of things:
- FAQ: Changing (X)HTML page encoding to UTF-8
- Declaring character encodings in HTML
- Tutorial: Character sets & encodings in XHTML, HTML and CSS
- Setting the HTTP charset parameter
They recommend using both the HTTP header and HTML meta tag (or XML declaration in case of XHTML served as XML).
Linux - Solution 3:
In addition to setting default_charset in php.ini, you can send the correct charset using header() from within your code, before any output:
header('Content-Type: text/html; charset=utf-8');click below button to copy the code. By - Linux tutorial - team
- Working with Unicode in PHP is easy as long as you realize that most of the string functions don't work with Unicode, and some might mangle strings completely.
- PHP considers "characters" to be 1 byte long. Sometimes this is okay (for example, explode() only looks for a byte sequence and uses it as a separator -- so it doesn't matter what actual characters you look for).
- But other times, when the function is actually designed to work on characters, PHP has no idea that your text has multi-byte characters that are found with Unicode.
- A good library to check into is phputf8.
- This rewrites all of the "bad" functions so you can safely work on UTF8 strings.
- There are extensions like the mbstring extension that try to do this for you, too, but I prefer using the library because it's more portable. But phputf8 can use mbstring behind the scenes, anyway, to increase performance.
Linux - Solution 4:
To use this for the PDO Connection string:
$pdo = new PDO(
'mysql:host=mysql.example.com;dbname=example_db',
"username",
"password",
array(PDO::MYSQL_ATTR_INIT_COMMAND => "SET NAMES utf8"));click below button to copy the code. By - Linux tutorial - team
Linux - Solution 5:
Here some information about unicode support in PHP
INTL
Good:
- Wrapper around ICU library
- Standardised locales, set locale per script
- Number formatting
- Currency formatting
- Message formatting (replaces gettext)
- Calendars, dates, timezone and time
- Transliterator
- Spoofchecker
- Resource bundles
- Convertors
- IDN support
- Graphemes
- Collation
- Iterators
Bad:
- Does not support zend_multibite
- Does not support HTTP input output conversion
- Does not support function overloading
mb_string
- Enables zend_multibyte support
- Supports transparent HTTP in/out encoding
- Provides some wrappers for funtionallity such as strtoupper
ICONV
- Primary for charset conversion
- Output buffer handler
- mime encoding functionality
- conversion
- some string helpers (len, substr, strpos, strrpos)
- Stream Filter stream_filter_append($fp, 'convert.iconv.ISO-2022-JP/EUC-JP')
DATABASES
- mysql: Charset and collation on tables and on connection (not the collation). Also don't use mysql - msqli or PDO
- postgresql: pg_set_client_encoding
- sqlite(3): Make sure it was compiled with unicode and intl support
Some other Gotchas
- You cannot use unicode filenames with PHP and windows unless you use a 3rd part extension.
- Send everything in ASCII if you are using exec, proc_open and other command line calls
- Plain text is not plain text, files have encodings
- You can convert files on the fly with the iconv filter