echo "hello world" pwd ls cat access.log tail -n 5 access.log grep "GET" access.log grep -c -P '\t' file-with-tabs.txt grep -l 500 * ls | grep 'access.log*' find . -type f -name "access.log*" -exec grep -hP '500' {} ; find . -type f -name "access.log*" -exec grep -oP '\d{1,3}.\d{1,3}.\d{1,3}.\d{1,3}' {} ; ??? ??? cat access.log | sort ??? ??? ??? rm -- -rm find . -type f -name ".doc" -exec rm {} ; ??? find . -type f -name "*.txt" -exec sed -i 's/challenges are difficult//g' {} ; ??? find . -type f -exec basename {} ;