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Stronger Shell

m.odul.us

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Re: Stronger Shell

#51

Post by vodik »

wereHamster wrote: post #4

> You must have spaces inside your test expressions (so [[-z $FOO]] won't work; [[ -z $FOO ]] is correct). That's because '[[' is a special bash extension which started out as a better '[' which is actually a binary (/usr/bin/[). And, well, you have to have a space between an executable and its first argument. (nowadays '[' and '[[' are builtins in most shells, but the external binary still exists).

The core difference is that:

- `[` is treated as a statement

- `[[` is treated as an expression

Which, for example, is why you can't use `>` in `[` based expressions. Bash thinks you want to redirect the output of `[` to somewhere else. This restriction is lifted for `[[` and makes for much more natural looking code.

Re: Stronger Shell

#52

Post by vodik »

omtose wrote: post #35
agentultra wrote: post #18

Earlier quoted context omitted.

I second fish. I've been using it as my primary shell for more than a few years now. The syntax is better than bash and familiar to those who've done programming in languages like Ruby or Python. The line editor is actually useful. It handles indentation and highlighting. It will display an appropriate help page if you mess up some command. It comes bundled with argument completion for most common Unix tools and is e…

With that example in particular, fish by default does not mess up file names containing spaces, as opposed to bash which treats them a separate files. I'm not sure why, but it's certainly useful.

What about files with newlines? evil smirk

Re: Stronger Shell

#53

Post by alpsgolden »

falcolas wrote: post #42
alpsgolden wrote: post #23

I've found that as soon as bash script goes to more than a couple lines, or as soon as it needs anything modestly complex, like "if" statements or functions, then it is almost always more efficient to write it in ipython. If you know python, then ipython is really superior way to do any ops and administration tasks. I've also found it easier to use for server setup than alternatives like ansible or puppet. I can just…

Perhaps it's just me, but flow control statements and functions in Bash have yet to scare me off. It's still faster, and readable, to write even moderately complex scripts in bash. This is doubly true if you have to chain together external scripts - the "easy" ways to do it in Python can have some very major limitations. I liken Bash scripting to Perl scripting. You can write safe, beautiful, and readable code in bot…

Part of this was that I became an expert in python before learning much bash, so it was just much easier to write in the language I already knew, and I found the bash syntax strange with a bunch of gotchas. I'm sure though, that if I did a ton of bash scripting I would not even notice the gotchas.

You are correct that the main weakness of ipython is that it doesn't have pipes, and that chaining is very limited. But usually this does not impact me. And if all your scripting is in python, then you just import functions and run them, rather than chaining scripts together.

Re: Stronger Shell

#54

Post by rnhmjoj »

realharo wrote: post #6

I personally can't stand bash for writing scripts (it's fine for typing one-liners into terminal though). This question and its top answer capture the insanity of bash quite nicely http://stackoverflow.com/questions/3601515/how-to-check-if-a... .

I completely agree: it's awful to do even simple things in a shell script. A shell should just be used as a shell: an interface for a human to the system in a terminal. The syntax for if-else, switch, loops, conditions is insane. I will never remember how to write a condition expression: just a missing space can break everything.

I quit using bash for scripting a few months ago. Now I use haskell with shell-conduit: http://chrisdone.com/posts/shell-conduit and bash only for very very simple things where haskell would be just overkill.

Re: Stronger Shell

#55

Post by trashcan »

useerup wrote: post #25
nimrody wrote: post #17

Earlier quoted context omitted.

Can you recommend a resource for learning powershell? (Assuming one has UNIX background) [it does generate annoyingly long error messages!]

Long error messages: Yes, they can be a little strange at first. If they annoy you (or you want errors to cause a little less scrolling) you can set the "error view": $ErrorView = "CategoryView" (unlike bash, whitespace is not significant) As for learning PowerShell, if you lean towards online training, Microsoft Virtual Acedemy has a really good series of courses, even featuring Jeffrey Snover - who is surprisingly…

Is Microsoft Virtual Academy worth the time? Every time I've tried to watch a video it's been 99% fluff. The video you linked to doesn't even open Powershell until 18 minutes in.

Re: Stronger Shell

#56

Post by EdiX »

david-given wrote: post #8
realharo wrote: post #6

I personally can't stand bash for writing scripts (it's fine for typing one-liners into terminal though). This question and its top answer capture the insanity of bash quite nicely http://stackoverflow.com/questions/3601515/how-to-check-if-a... .

Is there a better shell? By which I mean more flexible, more consistent, and simpler. (Anyone who says 'zsh' is disqualified.) I've briefly looked at rc, but while it's significantly simpler and more orthogonal than sh it's got it's own weirdnesses; but the 'Design Principles' section here is worth reading: http://plan9.bell-labs.com/sys/doc/rc.html Surely there must be a usable shell wrapped around an actual modern…

>Surely there must be a usable shell wrapped around an actual modern language?

AFAIK, the answer is no. I've spent a bit of time thinking about this problem and my conclusion is that the things that make a shell nice to use interactively are the same things that make it bad as a programming language. Rc may be as close as we will ever get to it.

Re: Stronger Shell

#57

Post by shadowfox »

felixgallo wrote: post #40
useerup wrote: post #13

Earlier quoted context omitted.

> Is there a better shell? By which I mean more flexible, more consistent, and simpler. Yes, PowerShell. And it may actually arrive at Linux/Unix soon, due to CoreCLR. The specification is already open, but until now not much progress has been made towards bringing it uncrippled to Linux/Unix PowerShell is extremely consistent. Examples: All commands are strictly on the verb-noun form where there are only 40 or so "a…

I had an opportunity to use PowerShell recently. The task was simple: on a bunch of freshly installed windows 8 boxes, kill a running graphical program of a certain name, copy over new executables, and restart that graphical program. The kind of thing you do essentially constantly on Unix boxes. I urge anyone at all with any interest in PowerShell to give it a shot. Spoiler: it's not possible without an epic level of…

> Anyone who thinks PowerShell is at all any good has, axiomatically, never seen any other shell besides cmd.exe before. You may think I'm exaggerating

Really. That feels like quite an uncharitable statement. The only reason someone could think something that you don't like is good because they just don't know any better?

Re: Stronger Shell

#58

Post by useerup »

felixgallo wrote: post #40
useerup wrote: post #13

Earlier quoted context omitted.

> Is there a better shell? By which I mean more flexible, more consistent, and simpler. Yes, PowerShell. And it may actually arrive at Linux/Unix soon, due to CoreCLR. The specification is already open, but until now not much progress has been made towards bringing it uncrippled to Linux/Unix PowerShell is extremely consistent. Examples: All commands are strictly on the verb-noun form where there are only 40 or so "a…

I had an opportunity to use PowerShell recently. The task was simple: on a bunch of freshly installed windows 8 boxes, kill a running graphical program of a certain name, copy over new executables, and restart that graphical program. The kind of thing you do essentially constantly on Unix boxes. I urge anyone at all with any interest in PowerShell to give it a shot. Spoiler: it's not possible without an epic level of…

Using the non-aliased verbose form of the cmdlets:

    $hosts = 'host1','host2','host3'
    $source = '\\host0\c$\source'
    $dest = 'c:\dest'
    $executable = 'C:\Program Files (x86)\Notepad++\notepad++.exe'

    Invoke-Command -Computer $hosts -ScriptBlock { 
        Get-Process | Where-Object Path -eq $using:executable | Stop-Process -Force
        Copy-Item -Path $using:source -Destination $using:dest
    }
Explanation:

Line 1-4: Set up variables to make the script more explanatory. Line 1 defines an array (the "," operator)

Line 6: Invoke-Command takes an array of (remote) hosts (the -Computer parameter) to execute the script block (the -ScriptBlock parameter).

Lines 7-9: The script to execute at each host simultaneously (the Invoke-Command executes the scripts in parallel at each host)

Line 7: Get the process list (Get-Process), pipe through the filter (Where-Object) which selects only the process(es) executing the desired executable, pipe those processes to the Stop-Process cmdlet which will forcably stop the process.

Line 8: Copy files from the desired source at an UNC path to the local machine at the destination

Now, the above script was the canonical way, using the long form. For casual scription, I could have written just this:

    $hosts = 'host1','host2','host3'
    $executable = 'C:\Program Files (x86)\Notepad++\notepad++.exe'
    icm $hosts { ps | ? Path -eq $using:executable | kill -f; cp \\host0\c$\source c:\dest }

Re: Stronger Shell

#59

Post by useerup »

felixgallo wrote: post #40
useerup wrote: post #13

Earlier quoted context omitted.

> Is there a better shell? By which I mean more flexible, more consistent, and simpler. Yes, PowerShell. And it may actually arrive at Linux/Unix soon, due to CoreCLR. The specification is already open, but until now not much progress has been made towards bringing it uncrippled to Linux/Unix PowerShell is extremely consistent. Examples: All commands are strictly on the verb-noun form where there are only 40 or so "a…

I had an opportunity to use PowerShell recently. The task was simple: on a bunch of freshly installed windows 8 boxes, kill a running graphical program of a certain name, copy over new executables, and restart that graphical program. The kind of thing you do essentially constantly on Unix boxes. I urge anyone at all with any interest in PowerShell to give it a shot. Spoiler: it's not possible without an epic level of…

> you will uncover that PS uses the same parameter to mean very different things for different commands

Example needed.

The claim is surprising, given that there exists a PowerShell Command Line Standard which includes a list of parameter names and their semantics: https://technet.microsoft.com/en-us/library/ee156811.aspx#EM...

Re: Stronger Shell

#60

Post by toothbrush »

klibertp wrote: post #16
toothbrush wrote: post #12

Earlier quoted context omitted.

> Anyone who says 'zsh' is disqualified. I'm curious as to why you say that? This is a naive question, i have no skin in the game.

Zsh is largely compatible with bash's quirks, and then layers lots of weird things of its own on top of that. ZSH is a great, very powerful shell which I use and enjoy, but it's not any of: "simple", "consistent", "fast" or "lightweight".

OK. Fair enough. I use zsh (only scratching the surface) because years ago it turned out that the completion "seemed" to me to be much more powerful (e.g., fuzzy matching, substring matching, etc.), but i haven't invested time to become a wizard. Do you (or anyone else here) endorse a shell which is worth becoming a wizard in? I'm thinking perhaps eshell or simply zsh-in-M-x-shell is perhaps a good starting point, but somehow that's always felt awkward to me, notably because completion seemed to be weaker than simply xterm+zsh.
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