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Comment by tkocmathla | Hacker News Reader

I love this, from a comment on the article:

  He had in his path a script called `\#` that he used to comment out pipe elements like `mycmd1 | \# mycmd2 | mycmd3`. This was how the script was written:
 
  ```
  #!/bin/sh
  cat
  ```

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A similar trick:

    #!/bin/sh
    $*

that's my `~/bin/noglob` file, so when I call a zsh script from bash that uses `noglob`, it doesn't blow up.

I think the script would be named as `#` so that it can be called via `\# mycmd` instead of `\\# mycmd`.

Yes! That one's going in my $PATH. Such a useful use of cat!

What does it provide over

mycmd1 #| mycmd2

Theirs "turns off" one element of a pipeline; yours turns off everything after a certain point.

This will output the stdout of mycmd1:

    mycmd1 #| mycmd2 | mycmd3

This will output the stdout of mycmd3:

    mycmd1 | \# mycmd2 | mycmd3

Can you explain to me why either of these is useful?

I've somehow gotten by never really needing to pipe any commands in the terminal, probably because I mostly do frontend dev and use the term for starting the server and running prodaccess

I can imagine a pipeline where intermediate stages have been inserted to have some side effect, like debug logging all data passing through.

Pipelines are usually built up step by step: we run some vague, general thing (e.g. a `find` command); the output looks sort of right, but needs to be narrowed down or processed further, so we press Up to get the previous command back, and add a pipe to the end. We run that, then add something else; and so on.

Now let's say the output looks wrong; e.g. we get nothing out. Weird, the previous command looked right, and it doesn't seem to be a problem with the filter we just put on the end. Maybe the filter we added part-way-through was discarding too much, so that the things we actually wanted weren't reaching the later stages; we didn't notice, because everything was being drowned-out by irrelevant stuff that that our latest filter has just gotten rid of.

Tricks like this `\#` let us turn off that earlier filter, without affecting anything else, so we can see if it was causing the problem as we suspect.

As for more general "why use CLI?", that's been debated for decades already; if you care to look it up :-)

no no, not asking why use CLI. If I was less lazy, I would use it more often

Ah duh, cheers

Wow I hate* that. I use bracket comments. They're cool cause they are bracket comments, so I use it in scripts to document pipelines. They are annoying cause they are bracket comments, in an interactive shell I have to type more and in TWO places. It's fun to reason-out how it works ;)

  $ echo foo | tr fo FO | sed 's/FOO/BAR/'
  BAR
  $ echo foo | ${IFS# tr fo FO | } sed 's/FOO/BAR/'
  foo

It's nice to have a way to both /* ... */ and // ... in shell scripts though:

  foo \
  | bar ${IFS Do the bar. Do it. } \
  | baz

* in the best possible way, like it's awful - I hate I didn't think of that

for multiline pipes, it's WAY better to format like

    foo   |
      bar |
      baz

You don't have to use backquotes, AND, it allows you to comment line by line, because there's no backslash messing with the parser.

I also use a last `|\ncat` so you can delete any line and you don't have to worry about the last line being a bit different than the rest

I created a list of similar tricks in https://github.com/kidd/scripting-field-guide in case anyone wants to take a look

You'll probably dislike this too:

  $ {
  >     echo foo \
  >     && echo bar \
  >     || echo baz ;
  > }
  foo
  bar
  <^P><^A>$<^F>IFS
  ${IFS#   echo foo   && echo bar   || echo baz ; }
  $ _

There's good and bad to both approaches. I like how I can use () and {} to bracket things and otherwise every line that end in \ is continued. I line-up on the left with the operator, you with indentation. When you use a # style comment, you have to look up and back and forward to see what the operator is you are continuing over to the next line:

  $ foo |
    bar | # ?Do? *the* $bar$ && [do] {it!}
    baz

Which only takes an extra neuron or so, but then history...

  <^P>
  $ foo |   bar | # ?Do? *the* $bar$ && [do] {it!}
  baz

aha! I see what you mean, it's indeed a nice option, yep.

Using brackets like this is something I never thought of, and it's probably why it's hard for me to process it, but I can see it provides nice annotation capabilities, and it's a more self-contained style.

Thx for sharing!

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