Grep last N characters of each line in a file

Question

I have a file with millions of lines.And each line ends with a format say "XXX:some value" .. I want to grep only this word "XXX:some value" from each line and put it in a separate file.How can i achieve this using grep command?

PS: "some value" can be any string

Answer 1

To get last n characters of each line using awk:

cat file
asdf
asdfg
asdfgh

awk -vn=2 '{print substr($0,length($0)-n+1)}'
df
fg
gh

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Or do you like to get data after XXX, then do:

echo "here is my line XXX:22" | awk -F"XXX:" '{print $2}'
22