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Groups > comp.os.linux.misc > #35740

Re: correct quoting for variables in bash scripts?

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* Eli the Bearded <*@eli.users.panix.com>
| In your example neither is needed. Firstly there's nothing adjoining to
| confuse the variable name. Secondly, it is [[ not [.
>
| The one [ ] square bracket form of the test command needs empty string
| protection because variable expansion happens before thecommand is run. 
>
| The two [[ ]] square bracket form of the test command is explicitly a
| shell built-in, so it can recognize empty strings without help.

Interesting, didn't know that difference:

    $ unset bar
    $ [[ $bar = x ]] && echo yes
    $ type [[
    [[ is a shell keyword
    
    $ [ $bar = x ] && echo yes
    bash: [: =: unary operator expected
    $ type [
    [ is a shell builtin

Most probably the error thrown with "[" is to ensure compatibility with
/usr/bin/test?

R'

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correct quoting for variables in bash scripts? Barry Stir <scooter@mealteam6.mil> - 2022-10-17 19:28 +0800
  Re: correct quoting for variables in bash scripts? Aragorn <telcontar@duck.com> - 2022-10-17 14:10 +0200
  Re: correct quoting for variables in bash scripts? Ralf Fassel <ralfixx@gmx.de> - 2022-10-17 14:15 +0200
    Re: correct quoting for variables in bash scripts? Jerry Peters <jerry@example.invalid> - 2022-11-01 20:27 +0000
  Re: correct quoting for variables in bash scripts? "Carlos E. R." <robin_listas@es.invalid> - 2022-10-17 14:39 +0200
  Re: correct quoting for variables in bash scripts? Rich <rich@example.invalid> - 2022-10-17 14:02 +0000
  Re: correct quoting for variables in bash scripts? Henning Hucke <h_hucke+spam.news@newsmail.aeon.icebear.org> - 2022-10-17 13:54 +0000
  Re: correct quoting for variables in bash scripts? Eli the Bearded <*@eli.users.panix.com> - 2022-10-17 23:35 +0000
    Re: correct quoting for variables in bash scripts? Ralf Fassel <ralfixx@gmx.de> - 2022-10-18 11:31 +0200
      Re: correct quoting for variables in bash scripts? Rich <rich@example.invalid> - 2022-10-18 12:02 +0000
        Re: correct quoting for variables in bash scripts? Ralf Fassel <ralfixx@gmx.de> - 2022-10-18 15:01 +0200
          Re: correct quoting for variables in bash scripts? Lew Pitcher <lew.pitcher@digitalfreehold.ca> - 2022-10-18 14:17 +0000
            The difference between /bin/test and /bin/[ Lew Pitcher <lew.pitcher@digitalfreehold.ca> - 2022-10-18 14:58 +0000
              Re: The difference between /bin/test and /bin/[ Eli the Bearded <*@eli.users.panix.com> - 2022-10-21 04:41 +0000
            Re: correct quoting for variables in bash scripts? Ralf Fassel <ralfixx@gmx.de> - 2022-10-19 12:04 +0200

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