Re: [Bitpim-devel] Startup script for BitPim on Macs

[Tom P. <mlp...@ea...>]

On Mar 15, 2004, at 2:16 PM, Steven Palm wrote:
>> In any case, I've attached a shell script that could be used to 
>> replace the current BitPim python startup script.  It uses a small 
>> shell function to extract the parent directory name from a filepath 
>> because the 'dirname' shell utility (like Python) is only there in 
>> MacOS X if the user installs the optional BSD package. Otherwise, 
>> it's just about line-for-line equivalent with the python version.
>
>  I'm not interested in removing the BSD subsystem from my computer to 
> test, but I see you state that `dirname` is not available unless you 
> install the BSD subsystem. You are using `sed`, however, so that one 
> *is* installed?

Yes, sed and awk are always installed on a minimal unix system.


> Given this kind of thinking, it's probably somewhat arbitrary what 
> commands Apple puts on your system as a CORE package versus the BSD 
> package, because I would land `sed` as a part of the BSD subsystem as 
> well, but it apparently is not.

It's understandable that this looks arbitrary to you, but it's not, 
really.  I was surprised that there was a 'dirname' utility at all, as 
soon as I saw it, because I know it's not standard.  That prompted me 
to check the Receipts directory to find which package it was installed 
with, and I found it was part of the BSD install.

(I have a perl script that lets you search your Receipts to see who 
installed what, if that sounds useful.  The Linux rpm system lets you 
ask questions like that easily, but I couldn't find anything for MacOS 
X that was comparable.  My perl script isn't really suitable for 
release, IMO, because it's kind of slow - it has to reread all of the 
receipts each time you run the script and that's an annoying delay.  It 
ought to cache that stuff somewhere, since it only rarely changes.)


> This makes it hard to be foolproof for future OS revisions as  well if 
> you write a shell script that depends on certain commands being there 
> (albeit minimal in this case.

Not really.  I've been dealing with cross-platform Unix issues for most 
of my career, and know how to write a portable Bourne shell script that 
you can expect to run pretty much anywhere.  (Not a terribly vital job 
skill nowadays, unfortunately.)  Sed and awk are always safe.  The main 
challenge is recognizing and avoiding shell features that are bash- or 
ksh-specific.  You might be surprised how much you can still do within 
these limitations.


Cheers,

Tom