How can I find encoding of a file via a script on Linux?

It sounds like you're looking for enca. It can guess and even convert between encodings. Just look at the man page.

Or, failing that, use file -i (Linux) or file -I (OS X). That will output MIME-type information for the file, which will also include the character-set encoding. I found a man-page for it, too :)

To convert encoding from ISO 8859-1 to ASCII:

iconv -f ISO_8859-1 -t ASCII filename.txt

It is really hard to determine if it is ISO 8859-1. If you have a text with only 7-bit characters that could also be ISO 8859-1, but you don't know. If you have 8-bit characters then the upper region characters exist in order encodings as well. Therefore you would have to use a dictionary to get a better guess which word it is and determine from there which letter it must be. Finally, if you detect that it might be UTF-8 then you are sure it is not ISO 8859-1.

Encoding is one of the hardest things to do, because you never know if nothing is telling you.

With this command:

for f in `find .`; do echo `file -i "$f"`; done

you can list all files in a directory and subdirectories and the corresponding encoding.

If files have a space in the name, use:

IFS=$'\n'
for f in `find .`; do echo `file -i "$f"`; done

Remember it'll change your current Bash session interpreter for "spaces".

In PHP you can check it like below:

Specifying the encoding list explicitly:

php -r "echo 'probably : ' . mb_detect_encoding(file_get_contents('myfile.txt'), 'UTF-8, ASCII, JIS, EUC-JP, SJIS, iso-8859-1') . PHP_EOL;"

More accurate "mb_list_encodings":

php -r "echo 'probably : ' . mb_detect_encoding(file_get_contents('myfile.txt'), mb_list_encodings()) . PHP_EOL;"

Here in the first example, you can see that I used a list of encodings (detect list order) that might be matching. To have a more accurate result, you can use all possible encodings via: mb_list_encodings()

Note the mb_* functions require php-mbstring:

apt-get install php-mbstring

This is not something you can do in a foolproof way. One possibility would be to examine every character in the file to ensure that it doesn't contain any characters in the ranges 0x00 - 0x1f or 0x7f -0x9f but, as I said, this may be true for any number of files, including at least one other variant of ISO 8859.

Another possibility is to look for specific words in the file in all of the languages supported and see if you can find them.

So, for example, find the equivalent of the English "and", "but", "to", "of" and so on in all the supported languages of ISO 8859-1 and see if they have a large number of occurrences within the file.

I'm not talking about literal translation such as:

English   French
-------   ------
of        de, du
and       et
the       le, la, les

although that's possible. I'm talking about common words in the target language (for all I know, Icelandic has no word for "and" - you'd probably have to use their word for "fish" [sorry that's a little stereotypical. I didn't mean any offense, just illustrating a point]).

I am using the following script to

1. Find all files that match FILTER with SRC_ENCODING
2. Create a backup of them
3. Convert them to DST_ENCODING
4. (optional) Remove the backups

#!/bin/bash -xe

SRC_ENCODING="iso-8859-1"
DST_ENCODING="utf-8"
FILTER="*.java"

echo "Find all files that match the encoding $SRC_ENCODING and filter $FILTER"
FOUND_FILES=$(find . -iname "$FILTER" -exec file -i {} \; | grep "$SRC_ENCODING" | grep -Eo '^.*\.java')

for FILE in $FOUND_FILES ; do
    ORIGINAL_FILE="$FILE.$SRC_ENCODING.bkp"
    echo "Backup original file to $ORIGINAL_FILE"
    mv "$FILE" "$ORIGINAL_FILE"

    echo "converting $FILE from $SRC_ENCODING to $DST_ENCODING"
    iconv -f "$SRC_ENCODING" -t "$DST_ENCODING" "$ORIGINAL_FILE" -o "$FILE"
done

echo "Deleting backups"
find . -iname "*.$SRC_ENCODING.bkp" -exec rm {} \;

I was working in a project that requires cross-platform support and I encounter many problems related with the file encoding.

I made this script to convert all to utf-8:

#!/bin/bash
## Retrieve the encoding of files and convert them
for f  `find "$1" -regextype posix-egrep -regex ".*\.(cpp|h)$"`; do
  echo "file: $f"
  ## Reads the entire file and get the enconding
  bytes_to_scan=$(wc -c < $f)
  encoding=`file -b --mime-encoding -P bytes=$bytes_to_scan $f`
  case $encoding in
    iso-8859-1 | euc-kr)
    iconv -f euc-kr -t utf-8 $f > $f.utf8
    mv $f.utf8 $f
    ;;
  esac
done

I used a hack to read the entire file and estimate the file encoding using file -b --mime-encoding -P bytes=$bytes_to_scan $f