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A comment on Shell Magic: Set Operations with uniq. Parent comment

Re:Shell Magic: Set Operations with uniq by fiddlerwoaroof on Wednesday May 30, 2018 @12:30AM (#17185080)
I always find it really confusing when the command-line begins with a redirect.
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Re:Shell Magic: Set Operations with uniq by unixhero on Wednesday May 30, 2018 @04:05AM (#17185940)
Yes, how do you parse that - ie. what does it even mean?
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Re:Shell Magic: Set Operations with uniq by moviuro on Wednesday May 30, 2018 @04:40AM (#17186086) 

  > a # from stdout to file
  < a # simply the opposite operation: from file to stdin
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Re:Shell Magic: Set Operations with uniq by fiddlerwoaroof on Wednesday May 30, 2018 @04:29AM (#17186038)
It's just a convention that redirects come after the command they're redirecting. There might be shell options that influence this, but I think all these are generally equivalent:

    foo bar < a
    foo < a bar
    < a foo bar
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Re:Shell Magic: Set Operations with uniq by paxunix on Wednesday May 30, 2018 @12:09PM (#17188902)
It is POSIX shell parsing behaviour that redirections can appear anywhere in the command (obviously, not in the same word as another parameter, nor inside a quoted string). They have to be stripped out by the shell before execution: http://pubs.opengroup.org/onlinepubs/9699919799/utilities/V3...
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