Using regular expressions with egrep and sed

We have now discussed both regular expressions and globbing. As we saw, they were very similar, but still had differences to be aware of. In our examples for regular expressions, and a little for globbing, we have already seen how grep can be used.

In this part, we'll introduce another command, which is very handy when combined with regular expressions: sed (not to be confused with set). We'll start with some advanced uses for grep.

Advanced grep

We have already discussed a few popular options for grep to alter its default behavior: --ignore-case (-i), --invert-match (-v), and --word-regexp (-w). As a reminder here's what they do:

• -i allows us to search case-insensitively
• -v only prints lines that are not matched, instead of matched lines
• -w only matches on full words that are surrounded by spaces and/or line anchors and/or punctuation marks

 

 

There are three other options we'd like to share with you. The first new option, --only-matching (-o) prints...