Network kanji filter: convert kanji code from one encoding to another. More information: https://manned.org/nkf.
nkf -w {{path/to/file.txt}}
nkf -s {{path/to/file.txt}}
nkf -w --overwrite {{path/to/file.txt}}
nkf -d --overwrite {{path/to/file.txt}}
nkf -c --overwrite {{path/to/file.txt}}
nkf -m --overwrite {{path/to/file.txt}}