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Comment by guylhem | Hacker News Reader

It is not very easy because it is an unusual request.

But I still wonder if this is easier than ls -l | sed -e :a -e 's/\(.*[0-9]\)\([0-9]\{3\}\)/\1,\2/;ta' ??

The investigations would be interesting it they were more complete, i.e. if the actual result was a change in the locale which could be appliable to other tools printing numbers besides ls (in the author TODO).

I mean, will it work with bc?

At the moment it's not better than an shell script alias giving the output to sed, but it is more complex - you have to recompile a binary for every OS you use.

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When I use your sed transformation on one of my directories, I see entries like:

    drwxr-xr-x  1,653 dalke  admin       56,202 Mar  5  2,012 pubchem
    -rw-r--r--     1 dalke  staff       59,252 Nov 16  2,011 pubchem_10,000.fps.0.9.cluster

I don't want to see the year written "2,012", and the file name is 'pubchem_10000" not "pubchem_10,000".

It's a 10 seconds trick that did the job and did not require recompiling.

EDIT: seeing how it has been downvoted, IMHO hacking is all about time and effectiveness. if you believe fixing ls print formats is such a crucial problem that it requires more than seconds of your time, we have different values.

Feel free to support the argument by showing your skills and improving the example.

You are entirely missing the point of this whole thing.

It is exactly about showing how hard it is to get a trivial change right in every detail. Your 10 second hack is what is wrong with 10 second hacks in general and even with most real solutions that are not carefully thought out.

It's not only that the devil is in the details it is all details. And you need to get all of them right, not just the current subset of the problem that you happen to be working on.

While I think that is the point, I don't know if was the author's originally intended point. You see 'hacking it' would imply just getting it to work, I expected to see something, well hackish, like replace the format specifier with %s and then wrap the number in a function call to something which read an environment variable to figure out how to print the number. That would be a hack, what Greg is doing is engineering a change to ls(1) which allows for pretty printing the numbers. So to my way of thinking the title is wrong, it sets the expectation of a hack and leads to an engineering exercise.

I think that's reflective of how experience levels change your perspective on how to approach a problem.

Someone with command line experience that is mostly a user of system utilities would think passing the output of ls through a filter is the way to go whereas someone with C experience that already has insight in how Unix is architected would do something more along the lines of what the author is doing. That's pretty much how unix got built to begin with, and probably both parties would qualify their solution as a 'hack'.

It's all perspective.

"Hacker" has many meanings. A quick read of the Wikipedia entry for the term shows you that. RFC 1392 defines a hacker as "A person who delights in having an intimate understanding of the internal workings of a system, computers and computer networks in particular." The only way to tell which definition is in use is via context, and for this case the meaning is unambiguously aligned with the RFC 1392 definition.

(Note that this RFC comes from the days when 'hacker' was becoming a widespread term for someone who breaks into computer systems; the RFC attempts to distinguish between a 'hacker' and a 'cracker.')

this should fix that. ls -l | sed -e :a -e 's/\s\(.*[0-9]\)\([0-9]\{3\}\) /\1,\2 /;ta'

correction: sorry it will only fix the modifications to the filename - the year is still broken.

The following modifies only the file size:

  ls -l | perl -pe 'while(s/^((\S+\s+){4})(\d+)(\d{3})([^\d].*)?$/$1$3,$4$5/){}'

Yes. So long as you only want to modify ls -l. And don't care about column alignment. The original author wants output to look like:

    -rw-r--r--  1 root  wheel  16,596,907,252 24 Dec  2009 boskoop.disk0.bz2 
    -rw-r--r--  1 grog  wheel   4,173,914,809 20 Jul  2006 boskopp.tar.gz

With your perl one-liner on my directory I get mis-aligned columns:

    -rw-r--r--     1 dalke  staff  3,236,397,056 Sep 13  2011 pubchem.fps
    -rw-r--r--     1 dalke  staff   712,181,172 Sep 13  2011 pubchem.fps.gz

That's ugly. It should be:

    -rw-r--r--     1 dalke  staff  3,236,397,056 Sep 13  2011 pubchem.fps
    -rw-r--r--     1 dalke  staff    712,181,172 Sep 13  2011 pubchem.fps.gz

The easiest and naive way to fix that is to buffer the whole thing. Don't use this to do `ls-comma -lR ~`, but only on small directory hierarchies.

https://github.com/samsonjs/bin/blob/master/ls-comma

It's a disgusting hack and it works very well. I didn't find anything useful in the man page so I wrote this instead. Looks like there is something in the man page but I think my hack was probably faster.

Your solution is the better one, but that does not take anything away from memset's argument, though... This is not about the solution. This is about the problem of having all these yaks to shave just to add a comma to some program's output.

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