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  • Perfect, +1! I said they were not relevant because I did not want to go into that much detail. I wanted an answer that could work as a quick cheatsheet for newbies who're wondering what all the weird squiggles at the end of the various commands are. I did not mean to imply they're not useful. Thanks for adding all this. Commented Oct 6, 2014 at 18:07
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    I'm concerned about the "critical mass" problem -- if we post everything that we could possibly say about shells, we'll end up with our own TL;DR version of the Bash Reference Manual. Commented Oct 6, 2014 at 18:09
  • Also worth mentioning: Unlike in languages of the C family, ; by itself (or without a command preceding it) is a syntax error, and not an empty statement. Thus ; ; is an error. (A common pitfall for new users, IMHO). Also: ;; is a special delimiter, for case statements. Commented Oct 6, 2014 at 18:10
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    @muru: Good point, but let's generalize it. Any of the control operators that can appear between commands: ;, &&, ||, &, and |, are errors if they appear with nothing preceding them. Also, terdon addressed ;; (briefly) in his answer. Commented Oct 6, 2014 at 18:31
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    @Wildcard: OK, I see where you're coming from.  The key word is "may"; all I was saying was that I don't guarantee that all shells will accept such constructs (i.e., YMMV).  Obviously I wrote that before I knew about the use of the linebreak token in the POSIX shell grammar.  So perhaps it's safe to say that all POSIX-compliant shells will accept them.  I stand by my statement as a general disclaimer; if you find an old enough pre-POSIX shell, such as an actual Bourne shell or older, all bets are off. Commented Mar 30, 2016 at 5:35