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For the Love of Pipes

blog.jessfraz.com

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Re: For the Love of Pipes

#151

Post by chrisfinazzo »

yaakushi wrote: post #85

I'm probably nitpicking, but if you're using cat to pipe a single file into the sdtin of another program, you most likely don't need the cat in the first place, you can just redirect the file to the process' stdin. Unless, of course, you're actually concatenating multiple files or maybe a file and stdin together. Disclaimer: I do cat-piping myself quite a bit out of habit, so I'm not trying to look down at the author…

I would be remiss if I did not point out that calling said program cat is a misnomer. Instead of 'string together in a series' (the actual dictionary definition, which coincidentally, pipes actually do) it quickly became 'print whatever I type to the screen.'

Of course, the example @arendtio uses is correct, because they obviously care about such things.

Re: For the Love of Pipes

#152

Post by chrisfinazzo »

richardwhiuk wrote: post #117
toxik wrote: post #106

Earlier quoted context omitted.

I think it's also a grammatical wart of shell syntax. Things going into a command are usually on the left, but piping in a file goes on the right.

is perfectly fine.

Of course, if any of your commands prompt for input, you'll be disappointed that's not always as easy as it appears on the surface.

Does anyone have a better way to do this kind of thing?

Re: For the Love of Pipes

#153

Post by longwave »

empath75 wrote: post #98
yaakushi wrote: post #85

I'm probably nitpicking, but if you're using cat to pipe a single file into the sdtin of another program, you most likely don't need the cat in the first place, you can just redirect the file to the process' stdin. Unless, of course, you're actually concatenating multiple files or maybe a file and stdin together. Disclaimer: I do cat-piping myself quite a bit out of habit, so I'm not trying to look down at the author…

People use cat to look at the file first, then hit up arrow, add a pipe, etc.

Yes, this. Quite often I start writing out complex pipelines using head/tail to test with a small dataset and then switch it out for cat when I am done to run it on the full thing. And it's often not worth refactoring these things later unless you are really trying to squeeze performance out of them.

Re: For the Love of Pipes

#154

Post by msla »

arendtio wrote: post #123
yaakushi wrote: post #85

I'm probably nitpicking, but if you're using cat to pipe a single file into the sdtin of another program, you most likely don't need the cat in the first place, you can just redirect the file to the process' stdin. Unless, of course, you're actually concatenating multiple files or maybe a file and stdin together. Disclaimer: I do cat-piping myself quite a bit out of habit, so I'm not trying to look down at the author…

In fact, I don't like people optimizing shell scripts for performance. I mean, shell scripts are slow by design and if you need something fast, you choose the wrong technology in the first place. Instead, shell script should be optimized for readability and portability and I think it is much easier to understand something like 'read | change >write' than 'change write'. So I like to write pipelines like this: cat foo…

I find something like this:

   grep '^x'
to be very readable, as the flow is still visually apparent based on punctuation.

Re: For the Love of Pipes

#155

Post by Sharlin »

chrisfinazzo wrote: post #151
yaakushi wrote: post #85

I'm probably nitpicking, but if you're using cat to pipe a single file into the sdtin of another program, you most likely don't need the cat in the first place, you can just redirect the file to the process' stdin. Unless, of course, you're actually concatenating multiple files or maybe a file and stdin together. Disclaimer: I do cat-piping myself quite a bit out of habit, so I'm not trying to look down at the author…

I would be remiss if I did not point out that calling said program cat is a misnomer. Instead of 'string together in a series' (the actual dictionary definition, which coincidentally, pipes actually do) it quickly became 'print whatever I type to the screen.' Of course, the example @arendtio uses is correct, because they obviously care about such things.

Having separate commands for outputting the content of a single file and several files would, however, be an orthogonality violation. YMMV whether having a more descriptive name for the most common use of cat would be worth the drawback.

Re: For the Love of Pipes

#156

Post by Asooka »

icebraining wrote: post #8

For an alternative view, don't forget to read the section on Pipes of The Unix-Haters Handbook : http://web.mit.edu/~simsong/www/ugh.pdf (page 198)

The section on find after pipes has also not aged well. I can see why GNU and later GNU/Linux replaced most of the old Unices (I mean imagine having a find that doesn't follow symlinks!). If I may, a bit of code golf on the problem of "print all .el files without a matching .elc"

  find . -name '*.el' | while read el; do [ -f "${el}c" ] || echo $el; done
Of course this uses the dreaded pipes and doesn't support the extremely common filenames with a newline in them, so let's do it without them

  find . -name '*.el' -exec bash -c 'el=$0; elc="${el}c"; [ -f "$elc" ] || echo "$el"' '{}' ';'

Re: For the Love of Pipes

#157

Post by chrisfinazzo »

DavidWoof wrote: post #90
OliverJones wrote: post #64

Earlier quoted context omitted.

MacOs is layered on a UNIX-like OS. You can use pipes in your command windows.

This comment makes me feel really old. MacOs wasn't always layered on unix, and the unix-haters' handbook predates the switch to the unix-based MacOs X.

Of course not, but the switch to BSD fixed a bunch of the underpinnings in the OS and was a sane base to work off of.

Not to put too fine a point on it, but they found religion. Unlike Classic (and early versions of Windows for that matter), there was more to be gained by ceding some control to the broader community. Microsoft has gotten better (PowerShell - adapting UNIX tools to Windows, and later WSL, where they went all in)

Still, for Apple it meant they had to serve two masters for a while - old school Classic enthusiasts and UNIX nerds. Reading the back catalog of John Siracusa's (one of my personal nerd heroes) old macOS reviews gives you some sense of just how weird this transition was.

Re: For the Love of Pipes

#158

Post by chrisfinazzo »

Sharlin wrote: post #155
chrisfinazzo wrote: post #151

Earlier quoted context omitted.

I would be remiss if I did not point out that calling said program cat is a misnomer. Instead of 'string together in a series' (the actual dictionary definition, which coincidentally, pipes actually do) it quickly became 'print whatever I type to the screen.' Of course, the example @arendtio uses is correct, because they obviously care about such things.

Having separate commands for outputting the content of a single file and several files would, however, be an orthogonality violation. YMMV whether having a more descriptive name for the most common use of cat would be worth the drawback.

It would fit in the broader methodology of 'single purpose tools that do their job well' or 'small pieces, loosely joined', but yes, probably too annoying to bother with.

Re: For the Love of Pipes

#159

Post by alias_neo »

nvarsj wrote: post #131
alias_neo wrote: post #2

Anyone else disappointed that this wasn't some in-depth, Docker related pipe usage post? For those of us that know who Jess is, the post is a little lacking. I went there to read about some cool things she's doing with pipe, but was disappointed at a post that contained nothing.

I think you're being downvoted because of: "Please don't post shallow dismissals, especially of other people's work. A good critical comment teaches us something." Having said that, it does seem like the author's posts seem to get upvoted no matter what by a contingent of readers. I also found TFA to be quite basic, and it couldn't have taken very much effort to write (I'm assuming the author is already well familiar…

It's unfortunate. I generally tend not to comment on things I want to criticise. I love Jess's work but saw zero value come from the time spent reading that.

I think my point was more valid, in this case, given that this isn't some random person trying to contribute something, I'd have been less critical in that case and not commented, but this is Jess Frazelle. Those of us that know the name know she's an extremely skilled engineer, and _that_ is why I was disappointed at the post.

Re: For the Love of Pipes

#160

Post by jfhufl »

benj111 wrote: post #10

Why isn't the pipe a construct that has caught on in 'proper' languages?

Hmmm, well that's why I like Ruby and other languages with functional approaches. Method chaining and blocks are very similar to pipes to me.

    cat /etc/passwd | grep root | awk -F: '{print $3}'

    ruby -e 'puts File.read("/etc/passwd").lines.select { |line| line.match(/root/) }.first.split(":")[2]'
A little more verbose, but the idea is the same.

https://alvinalexander.com/scala/fp-book/how-functional-prog...

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