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README.md

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+# ranlin — Choose a random line from a text file
+
+Implemented using an elegant algorithm, originally stolen from the "Perl
+Cookbook", which does not have more than a single text line in memory at any
+time.
+
+The trivial way to pick a random line would of course be to read all lines into
+an array, and then pick a random index for that array.
+
+The algorithm used here, however, will generate a random number between zero and
+the number of lines read, every time a line is read. Then, if that number is
+greater than one, the line will be taken as the resulting line, for that moment.
+
+Of course, when more lines are read after that, any line can be picked in that
+fashion, _where the chance the line is picked is still equal for evey line_.
+
+Brilliant.
+
+## Build
+
+`make`
+
+## Install
+
+`sudo make install`
+
+or, on OpenBSD:
+
+`doas gmake install`
+
+## Run
+
+`ranlin <textfile>`
+
+Output will be some random line from the file.