How to Remove Byte Order Marks (BOMs) from a UTF-8 File?

How to Remove Byte Order Marks (BOMs) from the Beginning of a File

Problem:

You encounter an issue with a CSS file containing invisible characters, denoted by , that disrupt its proper functioning when read by PHP. The file is saved in UTF-8 encoding, but removing the characters manually is challenging.

Answer:

The characters you are observing are known as Byte Order Marks (BOMs). A BOM is a Unicode character that indicates the byte order (endianness) of a file. In this case, the UTF-8 BOM signifies that the file uses UTF-8 encoding.

Solutions:

• Disable BOMs in Editor: Configure your editor to not insert BOMs when saving files. In some editors, you may find a setting related to "BOM."
• Strip BOMs with awk: Use the awk command-line utility to remove BOMs from the file:

awk 'sub(/^\xEF\xBB\xBF/, "")' input.css > output.css

• Handle BOMs in PHP: Set the PHP internal encoding to UTF-8 to ignore BOMs when reading files:

<?php
mb_internal_encoding('UTF-8');
// Read and process CSS files
mb_internal_encoding('previous encoding'); // Restore previous encoding
?>

Note:

• ISO-8859-15 encoding cannot represent the UTF-8 BOM, so saving the file in that format will result in data loss.
• Line endings (Windows vs. Linux) should not affect BOM detection.

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