Wow, Johns, thanks for the tips... I'm going to have to study that map
command very closely. Either way you've answered my question, thanks!
Only one thing to add-- you ask:
>> chomp $newtxt;
>> print $newtxt, "\n";
>
> Why remove "\n" in one line and then add it back on the next line?
I did this because I want to make sure I end with a "\n", but I don't want
an extra one if one is already there. I guess I could've also done a:
$newtxt =~ s/([^\n])$/$1\n/;
... but the above seemed clearer. Is that not a good reason?
- B
> Bryan Harris wrote:
>>
>> Is there a way to interpolate strings that the user enters?
>>
>> I'm writing a filter (pipe-cat = pat) that lets you add text to the front or
>> end of some piped data:
>>
>> echo "2" | pat "1" - "3\n"
>>
>> The "-" represents the piped data, so the above should print:
>>
>> % echo "2" | pat "1\n" - "3\n"
>> 1
>> 2
>> 3
>> %
>>
>> But here's what I get:
>>
>> % echo "2" | pat "1" - "3\n"
>> 1\n2
>> 3\n%
>>
>> How can I interpolate the "\n" that the user entered?
>
> $string =~ s/\\n/\n/g;
>
>
>> Here's my code (disclaimer: I'm still very much a novice at this stuff).
>>
>> #! /usr/bin/perl -w
>>
>> $newtxt = "";
>> while ($_ = shift) {
>> if ($_ eq "-") {
>> open(FILE, "-") || die("Couldn't read from STDIN: $!\n");
>> undef $/;
>> $newtxt .= <FILE>;
>> close(FILE);
>
> Since you are reading from STDIN and it is already open:
>
> if ( $_ eq '-' ) {
> local $/;
> $newtxt .= <STDIN>;
>
>
>> }
>> else { $newtxt .= $_; }
>> }
>> $/ = "\n";
>
> If you had used 'local $/;' above then you wouldn't have to set it here.
>
>
>> chomp $newtxt;
>> print $newtxt, "\n";
>
> Why remove "\n" in one line and then add it back on the next line?
>
>
>> exit(0);
>>
>> I'm also very much open to tips from the pros on this stuff.
>
> You could do it something like this:
>
> #!/usr/bin/perl
> use warnings;
> use strict;
>
> my %escapes = (
> '\\' => "\\",
> n => "\n",
> t => "\t",
> f => "\f",
> b => "\b",
> r => "\r",
> );
>
> my $newtxt = join '', map {
> s/\\([\\ntfbr])/$escapes{$1}/g;
> local $/;
> $_ eq '-' ? <STDIN> : $_
> } @ARGV;
>
> print $newtxt;
> exit 0;
>
> __END__
>
>
>
> John
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