

Someone with more experience on sed or awk should chime in, but out of memory something like this (which MOST LIKELY WONT WORK, verify it before running it on anything important):
find -name *mkv -exec sed -e's/file=.*/file=' > {}.changed \;
That, at least in theory, reads every .mkv file recursively in a current working directory, finds lines that contain “file=<whatever><EOL>” and replace that with “file=<EOL>” and stores the output to <original filename>.changed.
Also when sodium hydroxide reacts with acid it releases CO2 and it affects growth of at least some fungus. Also, if a brick sized fuel cell can provide 1kWh and single transatlantic flight consumes at least 20MWh you’d need a pile big enough to build a house which doesn’t sound feasible.
But I’m not a chemist either, I suppose it boils down to comparing negative effects between this new cell against kerosine. Plus there’s always the case which affects any new kind of storing energy where it’ll be indefinetly ‘ready for market in next 5 years’.