feat(lamp-in-the-dark): add subject, test and solution for the exercise

sh/tests/lamp-in-the-dark_test.sh

@@ -0,0 +1,28 @@
+#!/usr/bin/env bash
+
+# Unofficial Bash Strict Mode
+set -euo pipefail
+IFS='
+'
+
+FILENAME="student/lamp-in-the-dark.sh"
+
+# True if FILE exists and is a regular file
+if [ -f ${FILENAME} ]; then
+    # FILE exists and it's not empty
+    if [ -s ${FILENAME} ]; then
+        if [[ $(cat $FILENAME | grep echo | wc -l) -ne 0 ]]; then
+            echo "echo is not allowed in this exercise!"
+            exit 1
+        fi
+        submitted=$(bash $FILENAME)
+        expected=$(bash solutions/lamp-in-the-dark.sh)
+        diff <(echo "$submitted") <(echo "$expected")
+    else
+        echo "The file exist but is empty"
+        exit 1
+    fi
+else
+    echo "File does not exist"
+    exit 1
+fi

sh/tests/solutions/lamp-in-the-dark.sh

@@ -0,0 +1,6 @@
+#!/bin/bash
+
+sleep 4 &
+sleep 3 &
+sleep 2 &
+jobs

subjects/devops/lamp-in-the-dark/README.md

@@ -0,0 +1,39 @@
+## lamp-in-the-dark
+
+### Instructions
+
+Create a script `lamp-in-the-dark.sh` which will list all background jobs that are currently running in your shell.
+
+Add the following to your script:
+
+```console
+sleep 4 &
+sleep 3 &
+sleep 2 &
+```
+
+Expected output:
+
+```console
+# The processes running here are just an example
+$ ./lamp-in-the-dark.sh
+[1]   Running                 sleep 4 &
+[2]-  Running                 sleep 3 &
+[3]+  Running                 sleep 2 &
+$
+```
+
+### Hints
+
+You can use the `jobs` command to list all background jobs that are currently running in your shell. This will show you a list of all background jobs, along with their job numbers and status.
+
+```console
+$ jobs
+[1]+ Running ping google.com &
+[2]- Running sleep 100 &
+```
+
+- The flag `-l` show status and process IDs of all jobs.
+
+> You have to use Man or Google to know more about commands flags, in order to solve this exercise!
+> Google and Man will be your friends!