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Date: Wed, 10 Aug 2005 21:23:33 -0400
From: Christopher Faylor <cgf-no-personal-reply-please AT cygwin DOT com>
To: cygwin AT cygwin DOT com
Subject: Re: Programatically finding value of "cygdrive" prefix
Message-ID: <20050811012333.GC10161@trixie.casa.cgf.cx>
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On Wed, Aug 10, 2005 at 02:47:52PM -0700, L Anderson wrote:
>Christopher Faylor wrote:
>>On Wed, Aug 10, 2005 at 02:36:16PM -0400, Christopher Faylor wrote:
>>
>>>On Wed, Aug 10, 2005 at 11:23:00AM -0700, Linda W wrote:
>>>
>>>>Is there a way to find out in a bash script the cygdrive prefix?
>>>>I thought something simple like
>>>> mount -p|tail -1|cut -f1
>>>>but that incorrectly assumed the fields were tab delimited.
>>>>Since there can be spaces in the cygdrive prefix, I can't
>>>>use space a delimiter, example:
>>>># mount -p
>>>>Prefix              Type         Flags
>>>>/cyg drive posix path  system       binmode
>>>>----
>>>
>>>There may be a simpler way to do it, but this seems to work:
>>>
>>>mount -p | sed -n '2s/\([^ ]\)  *[^ ][^ ]*  *[^ ][^ ]*$/\1/p'
>>
>>
>>This is shorter:
>>
>>mount -p | sed -nr '2s/([^ ]) +\S+ +\S+$/\1/p'
>>
>
>Neither of which work if there is a space in the cygdrive prefix; viz a viz:
>
> Prefix              Type         Flags
>/cyg drive posix path  system       binmode

Actually yes they will.  Did you actually try the above?  I did.

>However,
>
>mount -p | sed -nr '2s/([^ ].*) +\S+ +\S+/\1/p'
>
>does the trick.

Here's a little exercise for you.  Test your version like this:

  bash$ echo "/cygdrive  a b c      system    binmode" |  sed -nr '1s/([^ ].*) +\S+ +\S+/\1 <<<HERE/p'
  /cygdrive  a b c      <<<HERE

i.e., trailing spaces, which is what you'd expect from your use of '.*'.

Now try testing my last version:

  bash$ echo "/cygdrive  a b c      system    binmode" | sed -nr '1s/(\S) +\S+ +\S+$/\1<<<HERE/p'
  /cygdrive  a b c<<<HERE

So, the only difference between my version and your version is that
yours includes trailing spaces.  I wouldn't call that a benefit.

cgf

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