A commenter on the article pointed out the "Useless use of cat".
What most users probably don't realize is that the redirection can be anywhere on the line, not just at the beginning. Putting an input redirection at the beginning of the command can make the data flow clearer: from the input file, through the command, to stdout:
< data.csv awk -F "|" '{ sum += $4 } END { printf "%.2f\n", sum }'
(This only works for simple commands; you can't do `< file if blah; then foo; else bar; fi`)
"Useless use of cat" is one of those boring pedantic comments that makes me cringe. Who cares? It's usually much more straightforward to build a pipeline from left to right, particularly for people who are just learning this stuff.
> It's usually much more straightforward to build a pipeline from left to right, particularly for people who are just learning this stuff.
True, however, people pointing out UUOC are in fact pointing out that you should not be building a pipeline at all. If you want to apply an awk / sed / wc / whatever command to a file, then you should just do that instead of piping it through a extraneous command.
Sure, as people always mention, in your actual workflow you might have a cat or grep already, and are building a pipeline incrementally; there's no reason to remove previous stuff to be "pure" or whatever. But if you're giving a canonical example, there's no reason to add unneeded commands.
What most users probably don't realize is that the redirection can be anywhere on the line, not just at the beginning. Putting an input redirection at the beginning of the command can make the data flow clearer: from the input file, through the command, to stdout:
(This only works for simple commands; you can't do `< file if blah; then foo; else bar; fi`)