feat(find-files-extention): add subject, test and solution for new a exercise

sh/tests/find-files-extension_test.sh

@@ -0,0 +1,18 @@
+#!/usr/bin/env bash
+
+# Unofficial Bash Strict Mode
+set -euo pipefail
+IFS='
+'
+
+script_dirS=$(cd -P "$(dirname "$BASH_SOURCE")" &>/dev/null && pwd)
+
+challenge() {
+	submitted=$(cd "$1" && bash "$script_dirS"/student/find-files-extension.sh)
+	expected=$(cd "$1" && bash "$script_dirS"/solutions/find-files-extension.sh)
+
+	diff <(echo "$submitted") <(echo "$expected")
+}
+
+challenge find-files-extension/folder1
+challenge find-files-extension/folder2

sh/tests/solutions/find-files-extension.sh

@@ -0,0 +1,3 @@
+#!/bin/bash
+
+find . -iregex '.*\.\(txt\)' -exec basename {} \; | cut -d "." -f 1

subjects/find-files-extension/README.md

@@ -0,0 +1,59 @@
+## find-files-extension
+
+### Instructions
+
+Create a file `find-files-extension.sh`, which will look, from the current directory and its sub-folders for:
+
+all the files with `.txt` extension.
+
+That command will only show the name of the files without the extension `.txt`.
+
+- You can use this for testing: https://assets.01-edu.org/devops-branch/find-files-extension-example.zip
+
+- What to use : `find`
+
+- The output should be exactly like the example bellow but with the expected name
+
+```console
+$pwd
+<..>/find-files-extension-example
+$./find-files-extension.sh | cat -e
+qwep$
+pq1$
+zzzz$
+ziko$
+wei$
+ek$
+$
+```
+
+### Hints
+
+`find` command is used to search and locate the list of files and directories based on conditions you specify for files that match the arguments:
+You can use REGEX in `find` command.
+
+```console
+$find ~/ -iregex '<REGEX>'
+<all files and folders in the user home that respect the specified regex>
+$
+```
+REGEX for txt files: `.*\.\(txt\)`
+
+`cut` command is a command-line utility that allows you to cut out sections of a specified file or piped data and print the result:
+
+```console
+$cat cut-example.txt 
+abc-lol
+testtest-abcx
+qwerty-azerty-x
+$cat cut-example.txt | cut -d "-" -f 1 # cut the lines with "-" as delimiter and print the first part.
+abc
+testtest
+qwerty
+$
+```
+
+May you will need to use `pipe (|)` and `&&`.
+
+> You have to use Man or Google to know more about commands flags, in order to solve this exercice!
+> Google and Man will be your friends!