Take the 2-minute tour ×

I have a PHP file that I created with VIM, but I'm not sure which is its encoding.

When I use the terminal and check the encoding with the command file -bi foo (My operating system is Ubuntu 11.04) it gives me the next result:

text/html; charset=us-ascii

But, when I open the file with gedit it says its encoding is UTF-8.

Which one is correct? I want the file to be encoded in UTF-8.

My guess is that there's no BOM in the file and that the command file -bi reads the file and doesn't find any UTF-8 characters, so it assumes that it's ascii, but in reality it's encoded in UTF-8.

share|improve this question
What non-ASCII characters are in your file? –  dan04 Jun 13 '12 at 17:13
add comment

1 Answer

up vote 3 down vote accepted

Well, first of all, note that ASCII is a subset of UTF-8, so if your file contains only ASCII characters, it's correct to say that it's encoded in ASCII and it's correct to say that it's encoded in UTF-8.

That being said, file typically only examines a short segment at the beginning of the file to determine its type, so it might be declaring it us-ascii if there are non-ASCII characters but they are beyond the initial segment of the file. On the other hand, gedit might say that the file is UTF-8 even if it's ASCII because UTF-8 is gedit's preferred character encoding and it intends to save the file with UTF-8 if you were to add any non-ASCII characters during your edit session. Again, if that's what gedit is saying, it wouldn't be wrong.

Now to your question:

  1. Run this command:

    tr -d \\000-\\177 < your-file | wc -c

    If the output says "0", then the file contains only ASCII characters. It's in ASCII (and it's also valid UTF-8) End of story.

  2. Run this command

    iconv -f utf-8 -t ucs-4 < your-file >/dev/null

    If you get an error, the file does not contain valid UTF-8 (or at least, some part of it is corrupted).

    If you get no error, the file is extremely likely to be UTF-8. That's because UTF-8 has properties that make it very hard to mistake typical text in any other commonly used character encoding for valid UTF-8.

share|improve this answer
The first command returned 0, and the second command didn't return an error, so we can say it's UTF-8. Thanks! –  ecantu Jun 13 '12 at 22:12
add comment

Your Answer


