Reading from/writing to files with variables substitutions

Qukz has asked for the wisdom of the Perl Monks concerning the following question:

Hello.

I have some boilerplate text files with some variables I'd like to substitute. I'd then like to create new files with the appropriate substitutions based on those; for example (one of the boilerplate text files):

Hello $FIRST_NAME. 

I'm writing on behalf of $COMPANY...
[download]

How would I go about using those files to create new files with the substituted values, so the new file would then be

Hello James. 

I'm writing on behalf of SoftLayer...
[download]

The following works

my $outfile = "new.txt";

open (OUTFILE, ">> $outfile") || die "Can't open $outfile\n";

print OUTFILE "\n";
print OUTFILE "Hello $FIRST_NAME.\n";
print OUTFILE "\n";
print OUTFILE "I'm writing on behalf of $COMPANY...";
[download]

But I can't figure out how to do the above while keeping the boilerplate text files seperate from the script itself and still printing the substituted variables rather than the literal names of the variables.

Any help would be greatly appreciated.

Comment on Reading from/writing to files with variables substitutions Select or Download Code

Replies are listed 'Best First'.
Re: Reading from/writing to files with variables substitutions by aitap (Curate) on Mar 28, 2013 at 07:36 UTC
So, you have a template and you want to process it? Template::Toolkit should be useful, if you don't mind changing your template syntax from `$substitution` to `[% substitution %]`. Sorry if my advice was wrong.	[reply] [d/l] [select]
Re: Reading from/writing to files with variables substitutions by Anonymous Monk on Mar 28, 2013 at 07:34 UTC
use a hash, see String::Interpolate/ String::Interpolate::RE , String::Defer, Interpolation, Template,Text::Xslate... Re^2: Write to existing file with character insert, perlrequick	[reply]
Re: Reading from/writing to files with variables substitutions by 2teez (Vicar) on Mar 28, 2013 at 08:29 UTC
Hi Oukz, Really, aitap's wisdom for me is the way to go, however, if I may suggest using `here-document` like so: `use warnings; use strict; my $first_name = "James"; my $company = "SoftLayer"; my $letter = << "COMPANY_LETTER"; Hello $first_name. I'm writing on behalf of $company .... COMPANY_LETTER my $outfile = "new.txt"; open my $fh, '>', $outfile or die "Can't open file: $!"; print $fh $letter; close $fh or die "can't close file: $!";` [download] If you tell me, I'll forget. If you show me, I'll remember. if you involve me, I'll understand. --- Author unknown to me	[reply] [d/l]
Re: Reading from/writing to files with variables substitutions by BillKSmith (Monsignor) on Mar 28, 2013 at 15:24 UTC
Use a hash and a regex with the /e option. `#!perl -p use strict; use warnings; #Usage: perl script.pl boiler.txt >outfile.txt BEGIN{ use vars qw( %hash $pattern ); %hash = ( FIRST_NAME => 'James', COMPANY => 'SoftLayer', ); $pattern = join '\|', keys %hash; } s/\$($pattern)/$hash{$1}/ge;` [download] Bill	[reply] [d/l]
Re: Reading from/writing to files with variables substitutions by perlaintdead (Scribe) on Mar 28, 2013 at 23:58 UTC
suggestion: it's best if you use 3 arg opens like: `open(FILE, ">>", "filename.txt");` [download]	[reply] [d/l]