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Re: find help about 'read' built-in command
From: |
Mike Stroyan |
Subject: |
Re: find help about 'read' built-in command |
Date: |
Wed, 14 Nov 2007 00:04:37 -0700 |
User-agent: |
Mutt/1.5.15+20070412 (2007-04-11) |
On Wed, Nov 14, 2007 at 01:11:12PM +0800, 龙海涛 wrote:
> it works.
> 3x very much.
>
> On Tue, 2007-11-13 at 21:51 -0700, Bob Proulx wrote:
>
> > 龙海涛 wrote:
> > > i want to store the current working dir to a variable, i write
> >
> > The most common way to save the present working directory to a
> > variable would be to use the $(...) form.
> >
> > test=$(pwd)
> > echo $test
By the way, the variable "$PWD" has the same current directory value
as "$(pwd)" .
Assigning with
test=$PWD
can be quite a bit faster than using $(pwd) to execute the pwd builtin.
$ s=$SECONDS;for (( i=1;i<10000;i++ )) ;do d=$(/bin/pwd);done;echo
$(($SECONDS-$s))
23
$ s=$SECONDS;for (( i=1;i<10000;i++ )) ;do d=$(pwd);done;echo $(($SECONDS-$s))
8
$ s=$SECONDS;for (( i=1;i<10000;i++ )) ;do d=$PWD;done;echo $(($SECONDS-$s))
0
The speed difference probably doesn't matter for most situations.
--
Mike Stroyan <mike@stroyan.net>