Q:
How to check if a package is installed in Perl
I'm trying to add to a web-page the code to check if a package is installed on the system.
So the code looks like this:
My question is, how do I install a package with a function?
A:
The script is_installed will always return undef if not installed because the $#ARGV is always -1.
The solution to this is to test that the index is greater than or equal to zero.
sub is_installed {
my $which = $#ARGV >= 0? $_[0] : undef;
print "do stuff with $which
";
}
I would also suggest to change the name of the function to is_installed as a package name is not a Perl name, it is a (globally) unique identifier. You can however call it is_installed or something else.
Packages are installed by means of Makefiles. In order to do this you have to add something like this to the Makefile:
install:
@if [ -f $@ ] ; then echo "Package $@ already installed"; \n else (cd $@ && make); fi
Verizon Wireless launches iPhone Music Promotion - tba
======
justlearning
They are probably going to be more successful than Apple from now onwards.
iPhone is simple, easy to use and of course, the functionality works on an
open basis (just unlike the AppStore which is walled).
~~~
jsz0
I wonder what percentage of new iPhone owners will actually
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