Question

I’m trying to find the parameters sent in all POST requests by looking at my production Rails log files. Right now I’m just using the following:

grep 'Started POST.*\/[fr]' log/production.log

This shows me when the POSTs happen but not the parameters. What I’d like is to do something along the lines of:

1. Store the line in sed’s hold buffer when it encounters the regex above
2. Print the contents of the hold buffer and the current line when it encounters “Parameters:”

Answer 1

As I understood you need to display line with regex and the following line. grep can do it itself:

grep -A1 'Started POST.*\/[fr]' log/production.log

with sed it will look like:

sed -n '/Started POST.*\/[fr]/{N;p}' log/production.log

or if not all following lines may content “Parameters” and you need only them:

sed -n '/Started POST.*\/[fr]/{N;/Parameters/p}' log/production.log