1. search string given in a file(case in-sensitively)
$grep -i "Amit" marks.txt
$grep -i "Line" * ###search all files under the directory recursively
2. print out the N lines along with target found
$grep -A N -i "case-insensitive" file_name
$grep -A N -r "case-sensitive" file_name
$ grep -A 2 -r "A" marks.txt
1) Amit Physics 80
2) Rahul Maths 90
3) Shyam Biology 87
3. search the string (case-sensitive)
$ grep -r "a" marks.txt
2) Rahul Maths 90
3) Shyam Biology 87
4) Kedar English 85
5) Hari History 89
$ grep -r "A" marks.txt
1) Amit Physics 80
$ grep -r "H" marks.txt
5) Hari History 89
4. print out multiple lines with multiple search words: -E
$grep -E 'string1|string2|string3|string4|string5' textName.txt
