1. Display a list of /usr/share/doc subdirectories containing information about shells.
find /usr/share/doc/ | xargs grep 'shells'
2. How many README files do these subdirectories contain? Don't count anything in the form of “README.a_string”.
find /usr/share/doc/ -name 'README' | wc -l
3. Can you find an alternative for wc -l, using grep?
grep -c '^'
4. Make a script that checks whether a user exists in /etc/passwd. For now, you can specify the user name in the script, you don't have to work with arguments and conditionals at this stage.
read -p "Please input the name" name cat /etc/passwd |grep $name
5. Display configuration files in /etc that contain numbers in their names.
find /etc/ -name "[0-9]"