Modifying Files
Until now we’ve only dealt with using ARGF to read input. When we’re dealing with files, though, it’s common that we might also want to make modifications to them. With its in-place mode, Ruby offers a simple way to do this. This is useful if you’re running a filter across many different files—a find-and-replace task, for example.
We can invoke this mode by passing the -i flag to Ruby. For example, if we wanted to work across a set of files and change the spelling of a word across them all—the British tranquillity to the U.S. tranquility, for example—we could write the following simple script:
| argf-sub.rb | |
| | ARGF.each do |line| |
| | puts line.gsub("tranquillity", "tranquility") |
| | end |
We can run the script in the same way as ...
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