Re: looping questions

In article <1191010028.753764.76290@xxxxxxxxxxxxxxxxxxxxxxxxxxxx>,
lerameur <lerameur@xxxxxxxxx> wrote:

: for my $hours ('00'..'23') {
: [...]
: $hours++;
: }

Your code is doing twice as much work as necessary to compute
the values of $hours:

1. Your for loop sets up a loop over '00' .. '23'
2. You increment $hours at the end of each iteration,
but the value is ignored.

You can remove the line with the increment.

: $file23 = glob("$timestamp2$hours*") ;

What if there's more than one match?

: if ($file23 == 1){
: system(`cp /input/fttr/traffic/$file23 /input/$Out_directory `);
: }

I don't see how the condition could ever be true because your
glob shouldn't match a file whose name is 1.

Perl's system operator wants a command to run, e.g.,

system("ls -l /etc/motd");

Backticks (``) also want a command. The value of a command
quoted with backticks is the output of running it. For example:

$ perl -e 'print `echo 1 + 2 | bc` * 4, "\n"'
12

You usually don't want to combine them as you've done because
that would run one command and then attempt to run its output
a second command, e.g.,

$ perl -e 'system `echo ls /`'

Consider the following improvements:

for my $hours ('00' .. '23') {
my $cmd = join " " => "cp",
"/input/fttr/traffic/$timestamp2$hours*",
"/input/$Out_directory";

system $cmd;
}

You could even condense your code to a single command:

my $base = "/input/fttr/traffic/$timestamp2";
system join " " => "cp",
map("$base$_*", '00' .. '23'),
"/input/$Out_directory";

Hope this helps,
Greg
--
Some cause happiness wherever they go; others whenever they go.
-- Oscar Wilde
.

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