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comm is a really useful tool, with one big caveat — you must make sure your input files are all sorted the exact same way. If not, you can get unexpected result
by pimlottc 7y ago
comm is a really useful tool, with one big caveat — you must make sure your input files are all sorted the exact same way. If not, you can get unexpected results, and worse, might not even realize it.
This may seem obvious, but there are many tiny ways that sorts can differ between locales, operating systems and programs (e.g. Excel), especially when dealing with Unicode. It may look the same 99% of the time, and you may not realize until later that you’ve accidentally filtered out values.
- nunoferreira 7y agoAbsolutely! From my experience I only use with listings from the same source with the same sort tool (mostly unix sort).
- TomNomNom 7y agoMy advice is to sort the files just-in-time using the shell: comm <(sort fileA.txt) <(sort fileB.txt)
- Hello71 7y agoGNU comm prints a warning if either file is not sorted, unless all input lines are pairable.