Sometimes I'd like to apply parameter expansion flags to a string or array literal in zsh. As an example use case, say that I want to split some comma-delimited string $arglist on commas, but prepend something to the front. It would be nice to be able to do this:


Of course there are other ways to solve this particular problem, and I know that I can always assign to a parameter first and then apply the flags. But the question is: can I apply flags directly to a literal somehow?


I think you are looking for :- parameter substitution:

$ restofarglist='abc,def'
$ echo ${(s/,/)${:-arg1,arg2,$restofarglist}}
arg1 arg2 abc def

From man zsh:

              If name is set, or in the second form is non-null, then substitute its value;
              otherwise substitute word.  In the second form name may be omitted, in  which
              case word is always substituted.

Actually you can make this example a little bit shorter:

$ echo ${${:-arg1,arg2,$restofarglist}//,/ }
arg1 arg2 abc def
  • For me (zsh 5.0.5) your first example only works if I put double quotes around the parameter: echo ${(s/,/)${:-"arg1,arg2,$restofarglist"}}. Without them I get "arg1,arg2,abc def" as output. – Adaephon Oct 7 '14 at 7:27
  • @Adaephon same here (v 5.0.6); anyone understand why? – Sean Mackesey Oct 7 '14 at 8:07
  • What does setopt return? – jimmij Oct 7 '14 at 12:25
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  • unsetopt braceccl and it should work without quotes as well. – jimmij Oct 7 '14 at 16:33

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