Elegant way to search for UTF-8 files with BOM?

By | December 17, 2017
Questions:

For debugging purposes, I need to recursively search a directory for all files which start with a UTF-8 byte order mark (BOM). My current solution is a simple shell script:

find -type f |
while read file
do
    if [ "`head -c 3 -- "$file"`" == $'\xef\xbb\xbf' ]
    then
        echo "found BOM in: $file"
    fi
done

Or, if you prefer short, unreadable one-liners:

find -type f|while read file;do [ "`head -c3 -- "$file"`" == $'\xef\xbb\xbf' ] && echo "found BOM in: $file";done

It doesn’t work with filenames that contain a line break,
but such files are not to be expected anyway.

Is there any shorter or more elegant solution?

Are there any interesting text editors or macros for text editors?

Answers:

What about this one simple command which not just finds but clears nasty BOM? 🙂

find . -type f -exec sed '1s/^\xEF\xBB\xBF//' -i {} \;

I love “find” 🙂

If you want just to show BOM files, use this one:

grep -rl $'\xEF\xBB\xBF' .

Questions:
Answers:

The best and easiest way to do this on Windows:

Total Commander → go to project’s root dir → find files (Alt + F7) → file types *.* → Find text “EF BB BF” → check ‘Hex’ checkbox → search

And you get the list 🙂

Questions:
Answers:
find . -type f -print0 | xargs -0r awk '
    /^\xEF\xBB\xBF/ {print FILENAME}
    {nextfile}'

Most of the solutions given above test more than the first line of the file, even if some (such as Marcus’s solution) then filter the results. This solution only tests the first line of each file so it should be a bit quicker.

Questions:
Answers:

If you accept some false positives (in case there are non-text files, or in the unlikely case there is a ZWNBSP in the middle of a file), you can use grep:

fgrep -rl `echo -ne '\xef\xbb\xbf'` .

Questions:
Answers:

I would use something like:

grep -orHbm1 "^`echo -ne '\xef\xbb\xbf'`" . | sed '/:0:/!d;s/:0:.*//'

Which will ensure that the BOM occurs starting at the first byte of the file.

Questions:
Answers:

You can use grep to find them and Perl to strip them out like so:

grep -rl $'\xEF\xBB\xBF' . | xargs perl -i -pe 's{\xEF\xBB\xBF}{}'

Questions:
Answers:

For a Windows user, see this (good PHP script for finding the BOM in your project).

Questions:
Answers:

An overkill solution to this is phptags (not the vi tool with the same name), which specifically looks for PHP scripts:

phptags --warn ./

Will output something like:

./invalid.php: TRAILING whitespace ("?>\n")
./invalid.php: UTF-8 BOM alone ("\xEF\xBB\xBF")

And the --whitespace mode will automatically fix such issues (recursively, but asserts that it only rewrites .php scripts.)

Questions:
Answers:
find -type f -print0 | xargs -0 grep -l `printf '^\xef\xbb\xbf'` | sed 's/^/found BOM in: /'
  • find -print0 puts a null \0 between each file name instead of using new lines
  • xargs -0 expects null separated arguments instead of line separated
  • grep -l lists the files which match the regex
  • The regex ^\xeff\xbb\xbf isn’t entirely correct, as it will match non-BOMed UTF-8 files if they have zero width spaces at the start of a line
Questions:
Answers:

I used this to correct only JavaScript files:

find . -iname *.js -type f -exec sed 's/^\xEF\xBB\xBF//' -i.bak {} \; -exec rm {}.bak \;

Questions:
Answers:

If you are looking for UTF files, the file command works. It will tell you what the encoding of the file is. If there are any non ASCII characters in there it will come up with UTF.

file *.php | grep UTF

That won’t work recursively though. You can probably rig up some fancy command to make it recursive, but I just searched each level individually like the following, until I ran out of levels.

file */*.php | grep UTF

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