Query Regarding Regular Expression

Shell Programming and Scripting
1

Can you please tell me the meaning of .*

For eg. i have a text as "Scrapple the apple"

Now here, what does a.*e will match?

2

It means "match any character, zero or more times, and be greedy about it". And for your text it will match "apple the apple"

3

But it is not working in my case :mad:

dsing1@[/export/home/dsing1] $ --> more exp
scrapple the apple
dsing1@[/export/home/dsing1] $ --> grep a.*e exp
scrapple the apple

4

Yes it is. grep returns the whole line if the regex is matching, not just the match.

5

so when i do a.*e then how will i get "apple the apple" from "scrapple the apple"

6 
$ echo "scrapple the apple"|sed 's/s.*r//1'
apple the apple

Thanks
Sha

7

Just as a hint, for source, listings, command line examples, ... please use the tags (or the '#' symbol in the advanced editor), it's easier to read.

$ perl -pe 's/.*?(a.*e).*/$1/' exp

Other people can probably add more examples (awk anyone?)

8 
echo 'scrapple the apple' | nawk '{for(i=1;i<=NF;i++) if($i ~ /a.*e/) printf("%s%c", $i, OFS); print ""}'