Convert file encodings between UTF-8 and GB2312

1. Check the encoding of a file with enca utility
   enca home.php
Universal transformation format 8 bits; UTF-8
2. Convert the encoding of the file with the GNU iconv utility (-c  omit invalid characters from output, -f from-encoding, -t to-encoding)
   iconv -c -f utf-8 -t gb2312 home.php > home.php.GB2312