Fix failing individual shell tools exercises

Author: RomanSanaye

individual-shell-tools/grep/script-04.sh

@@ -4,4 +4,4 @@ set -euo pipefail
 
 # TODO: Write a command to output every line in dialogue.txt that does not contain the word "Hello" (regardless of case).
 # The output should contain 10 lines.
-grep -iv "Hello" dialogue.txt
+grep -iv "Hello" dialogue.txt | grep -v '^$'

individual-shell-tools/ls/script-01.sh

@@ -13,4 +13,4 @@ fi
 
 # TODO: Write a command to list the files and folders in this directory.
 # The output should be a list of names including child-directory, script-01.sh, script-02.sh, and more.
-ls ls
+ls

individual-shell-tools/sed/script-06.sh

@@ -8,4 +8,5 @@ set -euo pipefail
 # The output should contain 11 lines.
 # Line 3 should be "It contains many lines, and there are some things you may want to do with each of them.".
 # Line 11 should be "We also should remember, when we go shopping, to get 4 items: oranges, cheese, bread, olives.".
-sed 's/,/, /g' input.txt
+
+sed 's/, */, /g' input.txt