What is the difference between -E and -e in grep in Kali Linux?

[KALIAK]

What is the difference between -E and -e in grep in Kali Linux? Because both are for regexp so which one is better to use and why? And the difference between both.

 

[dos2unix]

This isn't just a Kali thing, but...

The -e only lets me use one pattern after it. I can use -e twice or more if I want more patterns.

grep -e "pattern1" -e "pattern2" file.txt

If I use the -E option, I can use multiple patterns.

grep -E "pattern1|pattern2" file.txt

So not really a lot of difference, just slightly less typing the second way.

 

[CaffeineAddict]

-E option is used for extended regex

For an overview of extended regex see:

Regular Expressions/POSIX-Extended Regular Expressions - Wikibooks, open books for an open world

en.wikibooks.org

 

[KALIAK]

This isn't just a Kali thing, but...

The -e only lets me use one pattern after it. I can use -e twice or more if I want more patterns.

grep -e "pattern1" -e "pattern2" file.txt

If I use the -E option, I can use multiple patterns.

grep -E "pattern1|pattern2" file.txt

So not really a lot of difference, just slightly less typing the second way.

Thanks for clarifying my thought