Bash: fetch IP Address in a file using GNU grep

You can use below command

grep -oE "\b([0-9]{1,3}\.){3}[0-9]{1,3}\b" filename.txt 

BASH: Shell command to list only directories in the current working directory

To list only directories of your current working directory you can use below command

find ./* -maxdepth 0 -type d -exec basename {} \;