How to add CP932 charset to iconv in Alpine

I want to convert CP932 string to UTF-8.

In Ubuntu I can convert string by a command

iconv -f CP932 -t UTF-8 [input_file]

But the iconv in Apline 3.17 fails with a error: iconv: source charset CP932: Invalid argument.

How can I add CP932 charset to iconv?

The command is called from a ruby script so I don't adhere iconv if there is better way to convert string CP932 to UTF-8 with ruby or another command line tool in Alpine.

Compile iconv from source rather than installing it with a package.

1. Install the utilities necessary to build from source:

apk add --no-cache curl build-base

2. Download the source:

cd /tmp
curl -O https://ftp.gnu.org/pub/gnu/libiconv/libiconv-1.17.tar.gz
tar xvf libiconv-1.17.tar.gz
cd libiconv-1.17/

3. Configure, compile and install iconv to /usr/local/bin:

./configure
make
make install

4. Remove the downloaded source:

cd /tmp
rm -rf libiconv-1.17/
rm libiconv-1.17.tar.gz

---

Now you can run iconv successfully with CP932. Here's an example:

1. Create a new UTF-8 file:

echo "潤" > foo

2. Confirm it is UTF-8:

file -i foo
foo: text/plain; charset=utf-8

3. Convert it to CP932:

iconv -f UTF-8 -t CP932 foo > foo.cp932

4. Confirm it has been converted:

file -i foo.cp932
foo.cp932: text/plain; charset=unknown-8bit

and:

cat foo.cp932
��

5. Convert CP932 back to UTF-8:

iconv -f CP932 -t UTF-8 foo.cp932 > foo.utf8

6. Confirm it has been properly converted:

file -i foo.utf8
foo.utf8: text/plain; charset=utf-8

and:

cat foo.utf8
潤

and:

md5sum foo
54282143d705814d6ba671b783f2e0ba  foo

md5sum foo.utf8
54282143d705814d6ba671b783f2e0ba  foo.utf8