• ronigami@lemmy.world
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    23 hours ago

    Example of how parameter expansion matters?

    Generally if you are pasting file paths there is a better way to do that. Use find with exec, or xargs, or a for loop. Or, get the list in Vim and escape (quote) every line at once. Unless you have double quotes in the filename too (which is actually a crazy thing) it shouldn’t be a big deal.

    • Sonotsugipaa@lemmy.dbzer0.com
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      23 hours ago

      Expansion matters because using parameters without quotes automatically splits words, and IIRC a quoted array parameter can still be split into its members — as opposed to Zsh, where word splitting doesn’t happen unprompted and quoted array parameters are flattened into a single string.

      Generally if I want to run $HOME/random executable with spaces.exe through Wine in a terminal I copy the path in Dolphin (CTRL+SHIFT+C, or CTRL+ALT+C idr) and paste it, within quotes if needed (the four extra key inputs are the annoying part).

      I find that much faster than manually typing find "$HOME" -name "random executable with spaces.exe" -type x -exec wine "{}" \;, or opening an editor to insert backslashes.

      • ronigami@lemmy.world
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        19 hours ago

        Why on earth not just type wine ~/random and then hit tab to autocomplete? Or you could do

        wine `echo random*`
        

        AFAIK, if $file is a filename with spaces, then some_util ${file} will not split the filename.

        • Sonotsugipaa@lemmy.dbzer0.com
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          11 hours ago

          If the path to the dir is longer than $HOME, say, $HOME/Tools/modding/hd2-audio-modder/wwise/v123456789_idr_but_its_a_long_one/random file name with spaces, it makes more sense.

          I’ll try using the braces syntax, if it does prevent word splitting I wasn’t aware of it, though it’s still slightly inconvenient (3 key inputs for each brace on my kb) and I’d probably still use quotes instead if I had to use Bash and had the file path in a variable for some reason.

          … though at this point I’m probably overthinking it, atm I don’t recall better examples of my distaste for Bash expansion shenanigans.


          Did some testing, here’s what I found.
          Beware, it devolves into a rant against Bash and has little to do with the original topic - I just needed to scream into the void a little.

          # Zsh
          function argn { echo $#; }
          
          var='spaced string'
          argn $var
          # Prints 1: makes sense, no word splitting here
          
          var=(array 'of strings')
          argn $var
          # Prints 2: makes sense, I'm using a 2-wide array where I would
          #           want 2 arguments (the second one happens to have
          #           a whitespace in it)
          
          # Bash
          function argn { echo $#; }
          
          var='spaced string'
          argn $var
          # Prints 2: non-array variable gets split in 2 with this simple reference;
          #           I hate it, but hey, it is what it is
          
          argn ${var}
          # Prints 2: no, braces do not prevent word splitting as I think you suggested
          
          var=(array 'of strings')
          argn $var
          # Prints 1: ... what?
          
          echo $var
          # Prints array: ... what?!?
          #               It implicitly takes the first element?
          #               At least it doesn't word-split said first element, right?
          
          var=('array of' strings)
          argn $var
          # Prints 2:
          


          Upon further investigation:

          # Bash
          mkdir /tmp/bashtest ; cd /tmp/bashtest
          touch 'file 1'
          touch 'file 2'
          
          stat file*
          # Prints the expected output of 'stat' called on both files;
          # no quotes or anything, globbing just expands into
          # 2 arguments without *word* splitting
          
          files=('file 1' 'file 2')
          stat $files
          # stat: cannot statx 'file'
          # stat: cannot statx '1'
          # WHY? WHY DOES GLOBBING ACT SENSIBLY WHEN ARRAYS DO NOT?
          

          I get that the Bash equivalent to Zsh’s $array is ${array[@]}, but making $array behave like it does in Bash has no advantage whatsoever.
          … IS WHAT I WOULD SAY IF THAT WERE TRUE! YOU ALSO HAVE TO QUOTE "${array[@]}" BECAUSE WE LOVE QUOTES HERE AT BASH HQ!

          # ... continued from before
          stat "prefix ${files[@]}"
          # stat: cannot statx 'prefix file 1'
          # (regular 'stat' output for 'file 2')
          

          While this behavior doesn’t make much sense to me, it also doesn’t make sense for me to write that “prefix” within the quotes in the first place, right?
          YES. BECAUSE SPLITTING IS NOT WHAT YOU EXPECT WHEN YOU PUT STUFF IN QUOTES.

          Sorry, I’ll stop.

          • ronigami@lemmy.world
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            11 hours ago

            My bad, I was thinking of zsh. And I think it’s configurable there too so may not behave that way according to your settings. But it is at least the default on Mac.

            • Sonotsugipaa@lemmy.dbzer0.com
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              11 hours ago

              I use Zsh too, though at this point is becoming detrimental to my (already limited) Bash skills because of features like the ${^array}{1,2,3} syntax which I use in some scripts of mine, which in turn I wouldn’t dare try to translate to Bash.