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Comment by m463 | Hacker News Reader

In scripts, I usually do stuff like this

  command \
    --longopt1 \
    --longopt2 arg \
    argument

  command | \
    command 2 | \
    command 3 \
      --opt1 \
      --opt2 \
      arg

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It's nice but you cannot comment individual lines. For that you can go one step further and use arrays:

  cmd=(
    command
    -x -y
    --bar OPTARG
    ARG ARG
  )
  $cmd

This works in Zsh. In Bash that would be ${cmd[@]} I think. I use this with long qemu command lines where I often modify and comment out arguments during testing.

You can comment using a hack; check this out:

  command `# a comment` \
    --longopt1 `# another comment` \
    --longopt2 arg \
    argument

I didn't mean commenting arguments for documentation but commenting them out while you're writing and testing the script. I.e. this won't work:

  command `# a comment` \
    # --longopt1 \
    --longopt2 arg \
    argument

AFAIK there's no hack for this.

EDIT: Oh, `# a comment`. Didn't notice that. I'm going to explore it, thanks.

You should probably note that this hack spawns an additional shell process per comment :)

For bash, add quotes: "${cmd[@]}"

Otherwise, you'll get word splitting. E.g.,

  cmd=(
   test
   "!= !="
   !=
   ""
  )
  "${cmd[@]}" && echo Success
  ${cmd[@]} || echo Failure

If you have a very long command you can run ctrl x e (hold control press x, than e) and edit it in your $EDITOR.

I wish I had known this 20 years ago. Thanks!

You don't even need the \ if the | is the last character of the line.

Wow. I just realized I'm terrible for this. I usually format my programming pretty verbosely to make it future-readable but I'm terrible for not doing that in my scripts.

I'll add a comment or something explaining it but now I feel guilty and should probably go back and rewrite a few lines...

I mean—for long scripts I'll break them up but I haven't paid much mind to arguments/flags.

I do this if I have to look up the right flag to use. If it's something commonly seen like "grep -o" or "tar -xvzf" I assume whoever is maintaining the script (probably future me) will be more familiar with the abbreviations than the long versions.

Yeah good point. It did strike me, though, because I'd just written several scripts running JMeter commands and sort of breezed over how they're written even though I had to go and look up all the flags.

If I'm splitting across lines, I prefer to put the pipe _after_ the newline. Otherwise, I like the cut of your jib, and will likely do this with arguments in scripts from now on.

sometimes I do something like this:

  foo \
    --group1 \
    \
    --group 2 \
    --more-stuff 2 \
    | \
   bar \
    --bar-stuff

using a line with a single backlash or breaking out the pipe can make grouping stuff clear. well, I mean as clear as having to use backslashes which to me is a little inelegant. Personally python and its indenting strategy has grown on me especially since editor support makes it painless to use and visually excellent.

Downside: forgetting a \ will truncate the flags list, leading to unexpected behaviour followed by an error.

This is how I always do it do - I find it much more readable, and it leads to better diffs too.

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