Compare two files using linux comm command

Comm Command: (to use this command file must b first sorted like cat file|sort > file1)

for Common : comm -1 -2 file1 file2

Ignore
-1	Ignore File1
-2	Ignore File1
-3	Ignore common data

Example:
File1
1
2
3
4
5

File2
3
4
5
6
7

comm -1 -2 file1 file2 => 3,4,5

comm -1 -3 file1 file2 => 6,7

pregmatch for shell script

*     matches any string of zero or more characters
?     matches any single character
[ ]   matches any single character within the set
[! ]  matches any single character not in the set

These can be combined together to form more advanced patterns:
[Yy]* Matches any string starting with an upper or lower case y.

Use quotes or escape/back-slash the special characters if you wish to pattern match them specifically.