Extract data between two points in a text file

Question

How would it be possible to extract data between two points in a text file?

E.g.

Reply: [200/OK] bytes=29086 time=583ms

The value b

Answer 1

sed -n 's/.*time=\(.*\)ms/\1/p' < logfile

This sets up a regular expression that captures everything between the time= and ms into the first capture group (which is referred to on the right-hand-side as \1) and prints it.