Re: find help about 'read' built-in command

[Mike Stroyan]

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>