John Dillon wrote:
>
> According to
> http://vipe.technion.ac.il/~shlomif/lecture/Perl/Newbies/lecture2/argv.html
> the following program will do ...whatever (make a backup of files) and it
> takes the file specified at the command line. I guessed from this that one
> has a .pl file with the following script, execute it at c: by typing its
> name and then the program stops and asks you what file you want to specify.
> But this does not happen. So how do you get the filename into the script?
You type in the file name after the program name:
C:\> program.pl filename
> use strict;
>
> my $filename = $ARGV[0];
The @ARGV array contains the contents of the command line after the
program name.
C:\> program.pl -f filename 2 3
# $0 contains 'program.pl' or 'c:\program.pl'
# #ARGV[0] contains '-f'
# #ARGV[1] contains 'filename'
# #ARGV[2] contains '2'
# #ARGV[3] contains '3'
> open I, "<".$filename;
> open O, ">".$filename.".bak";
You should _ALWAYS_ verify that the files opened correctly.
open I, "<$filename" or die "Cannot open $filename: $!";
open O, ">$filename.bak" or die "Cannot open $filename.bak: $!";
And, since you are on Windows, you may want to binmode the files:
binmode I;
binmode O;
> print O join("",<I>);
You don't need a join() in there.
print O <I>;
However that will read the entire file into memory before printing it
out. This is more memory efficient:
print O while <I>;
> close(I);
> close(O);
John
--
use Perl;
program
fulfillment
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