RE: Multiple Parameters
Cool it works, thanks alot for your help. -Original Message- From: James Edward Gray II [mailto:[EMAIL PROTECTED] Sent: Monday, July 26, 2004 9:04 PM To: [EMAIL PROTECTED] Cc: Perl Beginners Subject: Re: Multiple Parameters On Jul 26, 2004, at 6:29 PM, [EMAIL PROTECTED] wrote: Thank you very much for your help, but i have one more question, is this the way that regex works or is it something in my code, every time i try to run the script to search for a comma and replace it with a new line character (\n) it just removes the commas but doesn't replace it with a new line character. What is it replacing them with? n's? I'm betting your shell is swallowing the \, turning \n into just n. If that's true, you have to get a \ past the shell first. On my Unix box, both \\n and '\n' work. Unfortunately, that doesn't solve your problem. Because then you'll replace ,s with a \ followed by an n. You want \n translated into a newline character, as it is in Perl's double quoted strings. We could search your string for a \ followed by an n and replace it with a newline character, but that opens a another can of worms: What if you really wanted to replace with a \ and an n? Given that, we can eval() your string to get Perl's string behavior. That'll do what you want in this case, but may complicate some other cases for you, say if you're making a CSV file and want to replace with . It's all tradeoffs. Here's a simple change to eval() your string: s/$search/qq($replace)/eeg; # update your search to this Hope that helps. James -- To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED] http://learn.perl.org/ http://learn.perl.org/first-response -- To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED] http://learn.perl.org/ http://learn.perl.org/first-response
Re: Multiple Parameters
(Let's keep our discussion on the list so all can help and learn.)
On Jul 25, 2004, at 8:09 PM, [EMAIL PROTECTED] wrote:
OK i still can't figure this out, i understand what you explained but i
still can't figure out why it doesn't want to write to the new file
and also
why it only removes the commas and doesn't replace it with the new line
character, i modified the code a little but now when i run it it gives
me
this weird message:
weird message
IO::File=GLOB(0x8132fe4)
You are printing an object. See below.
-new code
#!/usr/bin/perl
use IO::File;
use strict;
use warnings;
die Usage: script OLD_FILE, SEARCH, REPLACE, NEW_FILE\n
unless @ARGV == 4;
my($old_file, $search, $replace, $new_file) = @ARGV;
my $open_file = new IO::File;
my $fh = new IO::File $new_file;
You're not checking if this succeeds any more. What if it fails?
if ($open_file-open( $old_file)) {
while ($open_file){
s/$search/$replace/g;
print $fh;
Perl thinks you want to print $fh, not print TO $fh. We need to
clarify.
print $fh $_;
# or...
$fh-print();
}
$fh-close;
$open_file-close;
}
---
Just out of curiosity, why are we using the module for this? Don't get
me wrong, I love object oriented programming, but here the interface
seems to have bitten you a few times and you're not saving yourself any
work. Here's the mundane version:
#!/usr/bin/perl
use strict;
use warnings;
die Usage: $0 OLD_FILE, SEARCH, REPLACE, NEW_FILE\n
unless @ARGV == 4;
my($old_file, $search, $replace, $new_file) = @ARGV;
open IN, '', $old_file or die File error: $!;
open OUT, '', $new_file or die File error: $!;
while (IN) {
s/$search/$replace/g;
print OUT $_;
}
close IN;
close OUT;
__END__
Hope that helps.
James
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RE: Multiple Parameters
Thank you very much for your help, but i have one more question, is this the
way that regex works or is it something in my code, every time i try to run
the script to search for a comma and replace it with a new line character
(\n) it just removes the commas but doesn't replace it with a new line
character.
-Original Message-
From: James Edward Gray II [mailto:[EMAIL PROTECTED]
Sent: Monday, July 26, 2004 9:22 AM
To: [EMAIL PROTECTED]
Cc: Perl Beginners
Subject: Re: Multiple Parameters
(Let's keep our discussion on the list so all can help and learn.)
On Jul 25, 2004, at 8:09 PM, [EMAIL PROTECTED] wrote:
OK i still can't figure this out, i understand what you explained but i
still can't figure out why it doesn't want to write to the new file
and also
why it only removes the commas and doesn't replace it with the new line
character, i modified the code a little but now when i run it it gives
me
this weird message:
weird message
IO::File=GLOB(0x8132fe4)
You are printing an object. See below.
-new code
#!/usr/bin/perl
use IO::File;
use strict;
use warnings;
die Usage: script OLD_FILE, SEARCH, REPLACE, NEW_FILE\n
unless @ARGV == 4;
my($old_file, $search, $replace, $new_file) = @ARGV;
my $open_file = new IO::File;
my $fh = new IO::File $new_file;
You're not checking if this succeeds any more. What if it fails?
if ($open_file-open( $old_file)) {
while ($open_file){
s/$search/$replace/g;
print $fh;
Perl thinks you want to print $fh, not print TO $fh. We need to
clarify.
print $fh $_;
# or...
$fh-print();
}
$fh-close;
$open_file-close;
}
---
Just out of curiosity, why are we using the module for this? Don't get
me wrong, I love object oriented programming, but here the interface
seems to have bitten you a few times and you're not saving yourself any
work. Here's the mundane version:
#!/usr/bin/perl
use strict;
use warnings;
die Usage: $0 OLD_FILE, SEARCH, REPLACE, NEW_FILE\n
unless @ARGV == 4;
my($old_file, $search, $replace, $new_file) = @ARGV;
open IN, '', $old_file or die File error: $!;
open OUT, '', $new_file or die File error: $!;
while (IN) {
s/$search/$replace/g;
print OUT $_;
}
close IN;
close OUT;
__END__
Hope that helps.
James
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Re: Multiple Parameters
On Jul 26, 2004, at 6:29 PM, [EMAIL PROTECTED] wrote: Thank you very much for your help, but i have one more question, is this the way that regex works or is it something in my code, every time i try to run the script to search for a comma and replace it with a new line character (\n) it just removes the commas but doesn't replace it with a new line character. What is it replacing them with? n's? I'm betting your shell is swallowing the \, turning \n into just n. If that's true, you have to get a \ past the shell first. On my Unix box, both \\n and '\n' work. Unfortunately, that doesn't solve your problem. Because then you'll replace ,s with a \ followed by an n. You want \n translated into a newline character, as it is in Perl's double quoted strings. We could search your string for a \ followed by an n and replace it with a newline character, but that opens a another can of worms: What if you really wanted to replace with a \ and an n? Given that, we can eval() your string to get Perl's string behavior. That'll do what you want in this case, but may complicate some other cases for you, say if you're making a CSV file and want to replace with . It's all tradeoffs. Here's a simple change to eval() your string: s/$search/qq($replace)/eeg; # update your search to this Hope that helps. James -- To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED] http://learn.perl.org/ http://learn.perl.org/first-response
Re: Multiple Parameters
[EMAIL PROTECTED] wrote: Hello, I am trying to write a search and replace script that can accept multiple arguments, but i want the first argument to be the filename to read, the next one to be the string to search for, the next one to be the replacement string, and the last one to be the name of the new file it creates with the new changes, but i can't figure out how to seperate each argument, can some one tell me how to do something like this. Any help is very much VIA CLI: ./replace.pl /home/oldfile my dog spot your cat wiskers /home/newfile then in your script the are, in the the same order : $ARGV[0] $ARGV[1] $ARGV[2] $ARGV[3] There are modules to assist you with command line arguments as well at search.cpan.org (like using switches so that order doesn't matter, etc) HTH :) Lee.M - JupiterHost.Net appreciated. -- To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED] http://learn.perl.org/ http://learn.perl.org/first-response
RE: Multiple Parameters
Another question, so far i have this script:
#!/usr/bin/perl
use IO::File;
die Usage: script OLD_FILE, SEARCH, REPLACE, NEW_FILE\n
unless @ARGV == 4;
my($old_file, $search, $replace, $new_file) = @ARGV;
$fh = new IO::File $new_file;
if (defined $fh) {
while(){
s/$search/$replace/g;
print;
}
$fh-close;
}
But the first problem is that if i try to run the code like this:
perl script.pl old.txt , \n new.txt
it will remove all the commas but won't replace them with new line
characters it will just remove them.
Also when i try to run the script it gives me this error:
Can't open ,: No such file or directory at script.pl line 11, line 1.
Can't open \n: No such file or directory at script.pl line 11, line 1.
Can't open new.txt: No such file or directory at script.pl line 11, line
1.
Why am i getting these errors, and how can i fix this?
Thanks in advance.
-Original Message-
From: James Edward Gray II [mailto:[EMAIL PROTECTED]
Sent: Saturday, July 24, 2004 3:13 PM
To: [EMAIL PROTECTED]
Cc: [EMAIL PROTECTED]
Subject: Re: Multiple Parameters
On Jul 24, 2004, at 11:38 AM, [EMAIL PROTECTED] wrote:
I am trying to write a search and replace script that can accept
multiple
arguments, but i want the first argument to be the filename to read,
the
next one to be the string to search for, the next one to be the
replacement
string, and the last one to be the name of the new file it creates
with the
new changes, but i can't figure out how to seperate each argument, can
some
one tell me how to do something like this. Any help is very much
appreciated.
Well, command line arguments come into the program by way of the array
@ARGV. So first we should be sure you got the right number of
arguments:
die Usage: script OLD_FILE, SEARCH, REPLACE, NEW_FILE\n
unless @ARGV == 4;
Then we can use it:
my($old_file, $search, $replace, $new_file) = @ARGV;
Finally, just FYI, you can do what you describe with a one-liner:
perl -pi.bak -e 's/search/replace/g' old_file
Hope that helps.
James
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Re: Multiple Parameters
On Jul 25, 2004, at 12:55 PM, [EMAIL PROTECTED] wrote:
Another question, so far i have this script:
#!/usr/bin/perl
use strict;
use warnings;
The above two lines ask Perl to hold you to the laws of good
programming. In return, you'll get better error messages and warnings
about things that might not be what you intended. That's a good deal
anytime, but critical in early Perl learning.
Because it forces you to write cleaner code, it also helps us read your
code, which again, can only help you.
The biggest change these rules will hold you too is declaring your
variables before you use them. In Perl, that generally looks like
this:
my $some_scalar;# declare a scalar
my $some_scalar = 'initial value'; # declare a scalar and initialize it
with a string
You only have to change one line below to get the code to pass
strict. Can you see which one?
use IO::File;
die Usage: script OLD_FILE, SEARCH, REPLACE, NEW_FILE\n
unless @ARGV == 4;
my($old_file, $search, $replace, $new_file) = @ARGV;
$fh = new IO::File $new_file;
if (defined $fh) {
while(){
The above line isn't doing what you want. It walks through @ARGV,
opening those files, and reading from them line-by-line.
We didn't empty @ARGV with our test above, so first it will open
$old_file, which is what you want. When it finishes going through
that, it will try to open your $search pattern, as a file. As you can
see, problems start here and you get the warning messages you
mentioned.
The fix is to read from only what we intend. Instead of opening just
one file, open two, one for reading and one for writing. Then,
assuming you open the old file in $old, you just need to modify your
while loop to:
while ($old) {
s/$search/$replace/g;
print;
You don't want to print to the screen, you want to print to the new
file. Hint: You need and $fh in the above line somewhere.
Hopefully these tips will get you going. If they don't cry help again
and I'll give more specific answers. Good luck.
James
}
$fh-close;
}
But the first problem is that if i try to run the code like this:
perl script.pl old.txt , \n new.txt
it will remove all the commas but won't replace them with new line
characters it will just remove them.
Also when i try to run the script it gives me this error:
Can't open ,: No such file or directory at script.pl line 11, line
1.
Can't open \n: No such file or directory at script.pl line 11, line
1.
Can't open new.txt: No such file or directory at script.pl line 11,
line
1.
Why am i getting these errors, and how can i fix this?
Thanks in advance.
-Original Message-
From: James Edward Gray II [mailto:[EMAIL PROTECTED]
Sent: Saturday, July 24, 2004 3:13 PM
To: [EMAIL PROTECTED]
Cc: [EMAIL PROTECTED]
Subject: Re: Multiple Parameters
On Jul 24, 2004, at 11:38 AM, [EMAIL PROTECTED]
wrote:
I am trying to write a search and replace script that can accept
multiple
arguments, but i want the first argument to be the filename to read,
the
next one to be the string to search for, the next one to be the
replacement
string, and the last one to be the name of the new file it creates
with the
new changes, but i can't figure out how to seperate each argument, can
some
one tell me how to do something like this. Any help is very much
appreciated.
Well, command line arguments come into the program by way of the array
@ARGV. So first we should be sure you got the right number of
arguments:
die Usage: script OLD_FILE, SEARCH, REPLACE, NEW_FILE\n
unless @ARGV == 4;
Then we can use it:
my($old_file, $search, $replace, $new_file) = @ARGV;
Finally, just FYI, you can do what you describe with a one-liner:
perl -pi.bak -e 's/search/replace/g' old_file
Hope that helps.
James
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For additional commands, e-mail: [EMAIL PROTECTED]
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Re: Multiple Parameters
On Jul 24, 2004, at 11:38 AM, [EMAIL PROTECTED] wrote: I am trying to write a search and replace script that can accept multiple arguments, but i want the first argument to be the filename to read, the next one to be the string to search for, the next one to be the replacement string, and the last one to be the name of the new file it creates with the new changes, but i can't figure out how to seperate each argument, can some one tell me how to do something like this. Any help is very much appreciated. Well, command line arguments come into the program by way of the array @ARGV. So first we should be sure you got the right number of arguments: die Usage: script OLD_FILE, SEARCH, REPLACE, NEW_FILE\n unless @ARGV == 4; Then we can use it: my($old_file, $search, $replace, $new_file) = @ARGV; Finally, just FYI, you can do what you describe with a one-liner: perl -pi.bak -e 's/search/replace/g' old_file Hope that helps. James -- To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED] http://learn.perl.org/ http://learn.perl.org/first-response
