regex - grep challenge - extract search pattern after searching any number of characters

Question

Lets say I did this:

 echo stackoverflow > file
 grep sta[a-z]*w file

grep result is stackoverflow

But how do I get only original pattern sta & w?

Answer 1

grep -oE 'sta|w'

或者

grep -o 'sta\|w'

应该给你想要的。例如：

kent$   echo "stakoverflow"|grep -oE 'sta|w'
sta
w

Answer 2

如果您打算概括sta和w，那么此版本可能会有所帮助：

echo stackoverflow > file
grep 'sta[a-z]*w' file | sed 's/\(sta\)[a-z]*\(w\)/\1 \2/'