Delete strings with non-Ukrainian characters bash - bash

Question

Using file structure
foo_11: "Марія"
foo_112: "Superman"
FOOTLONG: "Subway"
foo_13: "Юлія"
I want to remove all strings that don't have at least one character from Ukrainian alphabet.
Script:
for i in *.txt;
do
sed '/[^А-ЯЄЇІа-яєїі]+/d' $i >$i.out
mv $i.out $i
done
doesn't do anything. What is wrong?
Using mac bash.

Answer 1

Assuming that your character class defining Ukrainian letters is correct, the following should work:
sed '/[А-ЯЄЇІа-яєїі]/!d' file
[А-ЯЄЇІа-яєїі] matches a Ukrainian letter anywhere on the line.
Note that even the letters that look like ASCII letters A I a i are actually Ukrainian (Cyrillic) letters with Unicode codepoints U+410 U+406 U+430 U+456.
! negates the match, meaning that only lines not containing at least 1 Ukrainian letter match.
d deletes those lines.
To put it all together:
for f in *.txt; do
sed -i '' '/[А-ЯЄЇІа-яєїі]/!d' "$f" # -i '' is BSD Sed syntax; GNU sed takes just -i
done
As for what you've tried:
As #StefanHegny points out in a comment on the question, + isn't supported when sed is not run with -E in order to enable extended regular expressions; without -E, the cumbersome \{1,\} must be used. (\+ is only supported by GNU sed, not by the BSD version of sed that macOS comes with).
However, even the fixed version of your command, sed '/[^А-ЯЄЇІа-яєїі]\{1,\}/d', doesn't do what you want: it deletes all lines that contain at least one non-Ukrainian-letter character, which eliminates all of your input lines, given that they all have ASCII-based field names and contain :.
You should double-quote variable references such as $i to protect them from shell expansions: "$i"
BSD Sed does support in-place updating with -i, but - unlike GNU Sed - it requires that an empty option-argument (indicating that no backup of the input file should be made) be specified as a separate argument: -i ''.
Your write-to-a-temp-file-first-then-replace-the-original approach works too, but it's generally better to use the following idiom: sed ... file > file.tmp && mv file.tmp file. Separating the mv command with && ensures that the original file is only replaced if the sed command succeeded.
That said, that doesn't help with logic errors as in the case at hand: despite outputting nothing, sed reports success in this case.

Answer 2

This code would achieve what you want (if I understood your question correctly):
grep -i "Я\|Є\|Ї\|І" /folder/file >> /tmp/result
The result is stored on /tmp/result
Note: I don't know Ukranian, so I'm sure I did not included all Ukranian characters, please add/delete Ukranian characters you want to match to the construction above.
Note2: this code is case insensitive thanks to grep -i so you only need to add the character once (lowercase or capital).
To put it on your loop it could be:
for i in *.txt;
do
grep -i "Я\|Є\|Ї\|І" "$i" > "$i".out
mv "$i".out "$i"
done
Edit: I edited this answer to make it simpler, and to add a loop to it.