Question

given the name of a file as an argument,the script reads the file name and creates a new file containing only lines which consist of one word.

An example input and output will be

There
are 20 students in the class.
[TAB][SPACE] Nearly
half of them are enrolled in FoS. The rest are in
Faculty-Of-ES.

The output from the script should look like

There
[TAB][SPACE] Nearly
Faculty-Of-ES.

Hello I am a beginner programmer and I am trying to learn bash scripting for over a month now but questions like this still stump me.
Please outline the general approach .Thank you

Answer 1

grep -P "^[\s]*[0-9A-Za-z-]+.?[\s]*$" test.txt

Where test.txt contains the input text.

Here I am defining a word as having zero or more whitespace in the beginning and end . Then any combination of alphabets, digits and - and optionally ending with a period.

NOTE :: This will not work if you are considering floating point numbers as a word. Hence your definition of a word defines the result and the regex.