HackerRank Grep #2 problem solution

In this HackerRank Grep #2 problem solution In this challenge, we practice using the grep command to find specified strings or regular expressions.

Task

You are given a text file that will be piped into your command through STDIN. Use grep to display all those lines that contain the word the in them.

The search should NOT be sensitive to case.

Display only those lines of the input file that contain the word 'the'.

Input Format

A text file will be piped into your command through STDIN.

Output Format

Output only those lines that contain the word 'the'. The search should NOT be case-sensitive. The relative ordering of the lines in the output should be the same as it was in the input.

Problem solution.

grep -i -w "the"

Second solution.

grep -iw "the"

Third solution.

egrep -w [Tt][Hh][Ee]

Fourth solution.

while read line;
do
    lin=`echo $line|grep -wi "the"`
    if [ -n "$lin" ]; then
        echo $lin
    fi
done