Spinner Function for Shell Scripts

[Devin Teske]

On Nov 19, 2010, at 7:12 AM, Christian Weisgerber wrote:

> Devin Teske <dteske at vicor.com> wrote:
> 
>>>> So, just as the subject-line says, ... here's an efficient and robust
>>>> spinner function compatible with many shells.
>>>>                       DONE=$( /bin/sh -c 'read -t 0 DONE; echo $DONE' )
>>> 
>>> Is this expected to be portable to other operating systems? The dash
>>> shell, used as /bin/bash in Ubuntu, does not acept the "-t" argument
>>> to the read builtin command. Using /bin/bash solves the problem.
>> 
>> I was shooting for bourne-shell,
> 
> FreeBSD's /bin/sh is *not* a Bourne shell.

I see that now from the sh(1) manual (had been assuming it was true to its roots from 4.4BSDLite -- ala FreeBSD-1.0). More akin to Korn shell while maintaining POSIX.2 spec.




> 
>> It's rather unfortunate that bourne-shell has what we need but is not
>> available on all operating systems since many OSes have started swapping
>> out bourne-shell for it's younger cousin.
> 
> A traditional Bourne shell, such as Solaris's, does not implement
> read -t at all.

Thanks!

I guess that means that this code is specific to FreeBSD. I guess that means I love FreeBSD even more than I did before. Unfortunately, that means that if I want to implement this spinner on any other platform, I'll have to resort to my previous impementations -- using backgrounding and/or temporary files on-disk.


> 
> -- 
> Christian "naddy" Weisgerber                          naddy at mips.inka.de
> 
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--
Cheers,
Devin Teske

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