Hacker News Reader

Comment by mm321 | Hacker News Reader

I think the unix design philosophy is great in theory, but in practice you get a lot of parts that have to be combined, this combination then gets tricky, so you will want a utility that just covers all the edges.

Lets see, I often use ls -tr

* the good thing about this is that it is very fast to type

* the bad part is that you have to memorize the incantation.

You could probably do it by a pipe (ls | sort <now it gets complicated here>)

* good: the good part is that every program does its job

* bad: also two programs have a larger footprint than one

* good: you can have it as an alias to make it short again

* bad: aliases can't be used in bash scripts, unless you explicitly source the file that defines the alias

* good/bad: you just shifted complexity from ls to sort

....

View on HN

> ls | sort <now it gets complicated here>

In Powershell, from memory:

  ls | sort -property time

https://msdn.microsoft.com/en-us/powershell/reference/5.1/mi...

"man ls" in bash showed me what I need, doing the same in powershell gave me some nonsense about Get-ChildItem.

In PowerShell, ls is an alias for Get-ChildItem.

That doesn't really help me though does it? "get-help Get-ChildItem" isn't any better. "get-help Get-ChildItem -examples" is a bit better, "get-help Get-ChildItem -detailed" is what I'm after, why on earth doesn't "man ls" map to that? It's the same story with sort.

Know how am I supposed to know what type ls returns and what properties are available? For that matter, how am I supposed to know what type of object I'm dealing with? Time isn't displayed by the command and is different to LastWriteTime, how do I discover that it's a property?

So far in this ultra simple example powershell is looking over complicated and under featured.

>Time isn't displayed by the command and is different to LastWriteTime, how do I discover that it's a property?

The command you're looking for is Get-Member or gm. In this case 'ls | gm' will give you what you want. In much the same way that you were told to type 'man', rather than type all combinations of three letter words, you'll have to either pickup a book or read an article to learn a system. As a novice you can't expect to be proficient on day 1 now can you?

Ok, I did "ls | gm" and it still doesn't list the time property and there is no documentation on what the properties mean (to be fair, they are self explanatory in this case). It also appears that it can return multiple types, which could add some complication.

You're right that bash/unix requires some learning, but in my experience it requires less upfront learning and it plateaus fairly quickly, when I try and do something twice as complex it will only by 1.1 times as complicated. Powershell on the other hand doesn't seem to plateau, something twice as complex tends to be twice as complicated (or more).

> Ok, I did "ls | gm" and it still doesn't list the time property

    LastAccessTime            Property       datetime LastAccessTime {get;set;}
    LastAccessTimeUtc         Property       datetime LastAccessTimeUtc {get;set;}
    LastWriteTime             Property       datetime LastWriteTime {get;set;}
    LastWriteTimeUtc          Property       datetime LastWriteTimeUtc {get;set;}

There is no Time property. Your initial command 'ls | sort -property time' simply sorts by nothing, i.e. effectively the same as using sort { $null }. I think that's what they were so confused by.

Yep, hence:

> In powershell from memory:

in that comment - I was on an iPad, and didn't have access to Powershell.

But it worked, it didn't complain about no time property like I'd expect.

It's a scripting language, essentially. Reading properties that don't exist most of the time just gives you $null. That being said, while there is Set-StrictMode, it only helps in this case for directly accessing properties of objects. Indirectly via Sort-Object still doesn't raise an error, annoyingly.

Its not for me to say what will or wont be easy for you to pickup, given your prior experience with bash. IMHO Powershell has gone so far beyond bash that its not even fair to compare them. PS has combined all the objected oriented APIs inside windows (WMI, .NET etc) and you don't have to constantly convert to and from strings, which is brittle to begin with. PS can simply pass around in-memory objects, making it far more efficient. Powershell also has real types and this helps reduce scripting errors. There are lots of nice things in powershell, so for e.g. even if you didn't know the properties, you can autocomplete after typing "ls | sort -property" and can choose one. AFAIK you can't do this on a shell that doesn't use objects. You'll find that the design of the command names is mostly consistent with verb-noun format. I'm not even a sysadmin, I do embedded systems programming, but I still appreciate some of the niceties in PS. For e.g.

Reading HN :

    irm https://news.ycombinator.com/rss

Stop all my VMs :

    get-vm | stop-vm

Stop all processes consuming more than 1GB:

    ps | ?{$_.WS -gt 1GB} | kill

Find all empty folders:

    ls -r | ?{-not($_|ls)}

All the PDFs that I downloaded this month:

    ls -r *.pdf | ?{$_.CreationTime -gt "4/1/2017"}

> how do I discover that it's a property?

There's a bunch of properties displayed by default, but if you want to see all of them:

  ls | select *

Since ls (gci, get-childitem) can list Environemnt variables, Registry entries, etc (which is awesome) these all have different properties.

  ls Env: | select *

However I do see your point: the docs could be better about explaining that.

What you read might not work on another UNIX. BSD has its own semantics making writing cross platform UNIX scripts (depending on how far you stray from POSIX) a pain. Though I admit, its not fair to compare it to a single vendor system like NT. :)

Wouldn't the man pages for bsd be updated to reflect any changes? I'm not sure if PowerShell will fare much better when it comes to program inconsistencies.

Never used powershell, is it really that hard to create an alias in powershell? http://stackoverflow.com/questions/24914589/how-to-create-pe...

Aliases in PowerShell only alias the command itself and can not supply any parameters or other processing. This makes certain things nice, in that Get-Help works straightforward with aliases, and tab completion for arguments as well, but it complicates the case where you want to supply default arguments or do other things. You can run Get-Content Function:help to see how it can be done. Essentially it consists of:

- Writing a function

- Redirecting to the correct help topic

- Replicating all parameters and parameter sets so that tab completion works

Of course, if help and completion are irrelevant to you (wouldn't work correctly out of the box for bash either, I guess), then it just consists of writing a wrapper function instead of setting an alias.

Like bash (where aliases are also limited) most people list make functions.

Hence, as your parent comment said, you've shifted complexity into sort.

Reply on news.ycombinator.com