[kw-pm] why is my $PWD uninitialized?

[Ryan Fox]

Have a look at Cwd. http://perldoc.perl.org/Cwd.html

On Mon, May 31, 2010 at 9:02 AM, Robert P. J. Day <rpjday at crashcourse.ca>wrote:

>
>  (aside:  i'm suddenly immersed in a bunch of perl code so while my
> perl is very rusty, i'm going to be asking some admittedly dumb
> questions over the next little while as i get back to speed.)
>
>  i'm rewriting a tutorial on the "udev" facility in linux, and it
> turns out that the source tarball has a "test" component that
> simulates plugging and unplugging various devices and checking the
> messages generated against what's expected.  very cool.
>
>  however, when i try to run the script on my ubuntu system:
>
> $ sudo test/udev-test.pl
> Use of uninitialized value $PWD in concatenation (.) or string at test/
> udev-test.pl line 1735.
>
> udev-test will run 142 tests:
>
> TEST 1: no rules
> device
> '/devices/pci0000:00/0000:00:1f.2/host0/target0:0:0/0:0:0:0/block/sda'
> expecting node/link 'sda'
> Use of uninitialized value $PWD in concatenation (.) or string at test/
> udev-test.pl line 1663.
> Use of uninitialized value $PWD in concatenation (.) or string at test/
> udev-test.pl line 1663.
> add:         error
> Can't exec "tree": No such file or directory at test/udev-test.pl line
> 1685.
>
> Use of uninitialized value $PWD in concatenation (.) or string at test/
> udev-test.pl line 1698.
> Use of uninitialized value $PWD in concatenation (.) or string at test/
> udev-test.pl line 1698.
> remove:      ok
> ... etc etc ...
>
>  the script udev-test.pl opens with:
>
> ...
> use warnings;
> use strict;
>
> my $PWD                 = $ENV{PWD};
> my $sysfs               = "test/sys/";
> ...
>
>  down at line 1735, there is:
>
> print CONF "udev_rules=\"$PWD\"\n";
>
>  while at line 1663:
>
>        if ((-e "$PWD/$udev_root$rules->{exp_name}") ||
>            (-l "$PWD/$udev_root$rules->{exp_name}")) {
>
> i'm baffled -- shouldn't that variable be initialized?  or am i just
> forgetting something hideously basic about my perl?
>
> rday
>
>
> --
>
> ========================================================================
> Robert P. J. Day                               Waterloo, Ontario, CANADA
>
>            Linux Consulting, Training and Kernel Pedantry.
>
> Web page:                                          http://crashcourse.ca
> Twitter:                                       http://twitter.com/rpjday
> ========================================================================
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