Manfred Lotz wrote:
Mr. Shawn H. Corey wrote:
On Sun, 2008-10-05 at 16:54 +0200, Manfred Lotz wrote:
my $DRYRUN="--dry-run";
my $cmd = q(rsync $DRYRUN -avh \
-exclude bla1 \
-exclude bla2 \
src tgtdir
};
system($cmd);
my $Dry_Run = '--dry-run';
my $Command_Template = q{rsync %s -avh
-exclude bla1 \
-exclude bla2 \
src tgtdir
};
my $command = sprintf $Command_Template, $Dry_Run;
my $status = system( $command );
die "system( $command ) failed\n" if $status;
Variables in all caps usually constants or special Perl variables.
I like to have it more generic, i.e. I like to have all variables
substituted which are defined.
I tried this (Here all variables with pattern /$[\w]+/ will be
substituted if they are known):
#! /usr/bin/perl -w
use strict;
my $file_pat = "*.sh";
my $l = q(ls $file_pat |
while read f; do
file $f
done
);
Why shell out to run 'ls' when you can get the file names directly in perl?
my @files = <*.sh>;
mcmd($l);
my $dir = "/var";
my $test = q(find $dir -type d -maxdepth 1);
Why shell out to run 'find' when you can get the directory names
directly in perl?
my @var_dirs = grep -d, </var/*>;
mcmd($test);
sub getvar {
my $A = shift;
my $B = eval "$A";
perldoc -q quoting
if ( defined $B ) {
return $B;
} else {
return $A;
}
}
sub mcmd {
my $A = shift;
$A =~ s/\$[\w]+/getvar "$&"/ge;
That is usually (better) written as:
$A =~ s/(\$\w+)/ getvar $1 /ge;
printf "Issuing command: %s\n",$A;
That is usually (better) written as:
print "Issuing command: $A\n";
system($A);
}
This seems to work. In this example $f will not be touched because it is
not defined.
Because I am a real Perl newbie I'd like to know if the code is "ok",
i.e. not too un-idiomatic.
John
--
Perl isn't a toolbox, but a small machine shop where you
can special-order certain sorts of tools at low cost and
in short order. -- Larry Wall
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