Re: Newline error

[joseph]

"Xavier Noria" <[EMAIL PROTECTED]> wrote in message 
news:[EMAIL PROTECTED]
> On Jun 6, 2006, at 14:16, John W. Krahn wrote:
>
>> Mr. Shawn H. Corey wrote:
>>>
>>> $output_file =~ s/\r//g;
>>> # chomp only removes linefeed characters \n
>>>
>>> # BTW, there is no such thing as a newline;
>>> # it is either a linefeed: \n ASCII LF 0x0A
>>> # or a carriage return: \r ASCII CR 0x0D
>>
>> "\n" is inherited from the C programming language and is the  newline 
>> escape
>> sequence.  On Unix and Unix-like systems the newline is equivalent  to 
>> the
>> ASCII line feed character but on other systems it could be one or more
>> different characters.
>
> To be more precise, "\n" in Perl is eq "\012" everywhere except in  Mac OS 
> pre-X, where it is eq "\015". In CRLF platforms like Win32  "\n" is 
> transparently converted to CRLF on writing and back on  reading by PerlIO 
> in text mode. Thus, in a regular line-oriented  script like
>
>   while (my $line = ) {
>   # work with $line
>   }
>
> $line ends with "\n" but does not contain a pair CRLF (assuming  native 
> conventions in the input). On the other direction, the string  "foo\n" has 
> length 4 in all systems. When you print that string into  a file in text 
> mode on Windows the bytes on disk have an extra  "\015", but that's 
> transparent to the programmer. That's the point of  using "\n" as 
> logical/portable newline in Perl.
>
> I have written an article about newlines in Perl not yet published.  All 
> those fine details are explained there.
>
> -- fxn
>
--expect me to read it..do give me a link once done, thanks. 



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Re: Newline error (Closed)

[joseph]

""Muma W."" <[EMAIL PROTECTED]> wrote in message 
news:[EMAIL PROTECTED]
> joseph wrote:
>> All,
>>
>> Just like to ask for correction on what's wrong with my script it gives 
>> spit out this error when i run it.
>>
>> Unsuccessful open on filename containing newline at disksize.pl line 8.
>> Can't open file No such file or directory
>>
>> But it runs without this error whenever i feed it up when an existing 
>> file output by df-h.
>> ex:## open(FL,"path/toactual/file") or die "blabalha";
>> Does this mean it can't trap the output of  `df-h`?
>>
>> Here's the script###
>>
>> #!/usr/bin/perl
>>
>> use strict;
>> use warnings;
>>
>> chomp(my $output_file = `df -h`);
>>
>
> Df can return multiple lines. I'd suspect that your string $output_file
> has several embedded newlines in it at this point. Chomp will only
> remove that last (not embedded) newline.
>
>> open(FL,"$output_file") or die "Can't open file $!\n";
>> my @list;
>> my %disk;
>> my($label,$size,$use,$avail,$percent,$mounted,$partition,$usage);
>> while() {
>>  ($label,$size,$use,$avail,$percent,$mounted) = split(/\s+/, $_);
>>  push @list,$mounted,$percent;
>
> You might not need the intermediate list:
> $disk{$mounted} = $percent;
>
>> }
>>
>> %disk =(@list);
>> delete $disk{"Mounted"};
>>
>>
>>
>> foreach (sort keys %disk) {
>>my $value = $disk{$_};
>>print "\t $_ => $value \n";
>> }
>>
>>
>>
>>
>
> I'd do it like this:
>
> use strict;
> use warnings;
> use Data::Dumper;
>
> my %disk;
> for (`df -h`) {
> next if ! m{/};
> my($label,$size,$use,$avail,$percent,$mounted,$partition,$usage) =
> split /\s+/, $_;
> $disk{$mounted} = $percent;
> }
> print Dumper(\%disk);
>
> __END__
>
> You'll notice that the backticks operator (``), in a list context,
> returns a list containing each line as a separate list element.
>
> Since you only seem to need two elements from the list returned by
> split(), you could change the two lines after the "m{/}" to this:
>
> my @list = split /\s+/, $_;
> $disk{$list[5]} = $list[4];
>
> HTH

Thank you, your way resemble with the first option John Krahn reply..i'm 
just late to close the thread due to timezone difference still i appreciate 
your effort.



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Re: Newline error

[joseph]

""John W. Krahn"" <[EMAIL PROTECTED]> wrote in message 
news:[EMAIL PROTECTED]
> joseph wrote:
>> All,
>
> Hello,
>
>> Just like to ask for correction on what's wrong with my script it gives 
>> spit
>> out this error when i run it.
>>
>> Unsuccessful open on filename containing newline at disksize.pl line 8.
>> Can't open file No such file or directory
>>
>> But it runs without this error whenever i feed it up when an existing 
>> file
>> output by df-h.
>> ex:## open(FL,"path/toactual/file") or die "blabalha";
>> Does this mean it can't trap the output of  `df-h`?
>>
>> Here's the script###
>>
>> #!/usr/bin/perl
>>
>> use strict;
>> use warnings;
>>
>> chomp(my $output_file = `df -h`);
>
> `df -h` does not return a file name, it returns the same output as if you 
> had
> run the command 'df -h' on the command line.
>
>
>> open(FL,"$output_file") or die "Can't open file $!\n";
>> my @list;
>> my %disk;
>> my($label,$size,$use,$avail,$percent,$mounted,$partition,$usage);
>> while() {
>
> There are two basic ways to do what you want:
>
> 1.  for ( `df -h` ) { ... }
>
> 2.  open FL, 'df -h |' or die "Cannot open df pipe: $!";
>while (  ) { ... }
>close FL or warn $! ? "Error closing df pipe: $!"
>: "Exit status $? from df";
>
>
>>  ($label,$size,$use,$avail,$percent,$mounted) = split(/\s+/, $_);
>
> You are only using two of the values so you can simplify that to:
>
>   my ( $percent, $mounted ) = ( split )[ -2, -1 ];
>
>
>>  push @list,$mounted,$percent;
>
> You don't need the array, you can assign directly to the hash:
>
>   $disk{ $mounted } = $percent unless $mounted eq 'Mounted';
>
>
>> }
>>
>> %disk =(@list);
>> delete $disk{"Mounted"};
>
>
>
> John
> -- 
> use Perl;
> program
> fulfillment

Noted, thanks.. for all the helpful feedback it makes my learning stage 
worthwhile. 



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Re: Newline error

[joseph]

""Mr. Shawn H. Corey"" <[EMAIL PROTECTED]> wrote in message 
news:[EMAIL PROTECTED]
> On Tue, 2006-06-06 at 18:59 +0800, joseph wrote:
>> All,
>>
>> Just like to ask for correction on what's wrong with my script it gives 
>> spit
>> out this error when i run it.
>>
>> Unsuccessful open on filename containing newline at disksize.pl line 8.
>> Can't open file No such file or directory
>>
>> But it runs without this error whenever i feed it up when an existing 
>> file
>> output by df-h.
>> ex:## open(FL,"path/toactual/file") or die "blabalha";
>> Does this mean it can't trap the output of  `df-h`?
>>
>> Here's the script###
>>
>> #!/usr/bin/perl
>>
>> use strict;
>> use warnings;
>>
>> chomp(my $output_file = `df -h`);
>
> $output_file =~ s/\r//g;
> # chomp only removes linefeed characters \n
>
> # BTW, there is no such thing as a newline;
> # it is either a linefeed: \n ASCII LF 0x0A
> # or a carriage return: \r ASCII CR 0x0D

I still have to dig on this topic, i assume  it works the same way like the 
sample on a book like this # chomp($file = `date`);

>
>>
>> open(FL,"$output_file") or die "Can't open file $!\n";
>
> ... or die "cannot open file '$output_file': $!\n";
> # print out the contents so you can see exactly what it contains.

Unsuccessful open on filename containing newline at disksize.pl line 8.
Can't open file: FilesystemSize  Used Avail Use% Mounted on
/dev/cciss/c0d0p7 1.9G  215M  1.6G  12% /
/dev/cciss/c0d0p8  12G  9.8G  1.4G  87% /backup
/dev/cciss/c0d0p1  96M   16M   76M  17% /boot
/dev/cciss/c0d0p2  38G   24G   12G  66% /home
none  1.9G 0  1.8G   0% /dev/shm No such file or 
directory

#It's present right?

Thanks for input.

>
>> my @list;
>> my %disk;
>> my($label,$size,$use,$avail,$percent,$mounted,$partition,$usage);
>> while() {
>>  ($label,$size,$use,$avail,$percent,$mounted) = split(/\s+/, $_);
>>  push @list,$mounted,$percent;
>> }
>>
>> %disk =(@list);
>> delete $disk{"Mounted"};
>>
>>
>>
>> foreach (sort keys %disk) {
>>my $value = $disk{$_};
>>print "\t $_ => $value \n";
>> }
>
>
>
> -- 
> __END__
>
> Just my 0.0002 million dollars worth,
>   --- Shawn
>
> "For the things we have to learn before we can do them, we learn by doing 
> them."
>  Aristotle
>
> * Perl tutorials at http://perlmonks.org/?node=Tutorials
> * A searchable perldoc is at http://perldoc.perl.org/
>
> 



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Re: Newline error

[Xavier Noria]

On Jun 6, 2006, at 14:16, John W. Krahn wrote:


Mr. Shawn H. Corey wrote:


$output_file =~ s/\r//g;
# chomp only removes linefeed characters \n

# BTW, there is no such thing as a newline;
# it is either a linefeed: \n ASCII LF 0x0A
# or a carriage return: \r ASCII CR 0x0D


"\n" is inherited from the C programming language and is the  
newline escape
sequence.  On Unix and Unix-like systems the newline is equivalent  
to the

ASCII line feed character but on other systems it could be one or more
different characters.


To be more precise, "\n" in Perl is eq "\012" everywhere except in  
Mac OS pre-X, where it is eq "\015". In CRLF platforms like Win32  
"\n" is transparently converted to CRLF on writing and back on  
reading by PerlIO in text mode. Thus, in a regular line-oriented  
script like


  while (my $line = ) {
  # work with $line
  }

$line ends with "\n" but does not contain a pair CRLF (assuming  
native conventions in the input). On the other direction, the string  
"foo\n" has length 4 in all systems. When you print that string into  
a file in text mode on Windows the bytes on disk have an extra  
"\015", but that's transparent to the programmer. That's the point of  
using "\n" as logical/portable newline in Perl.


I have written an article about newlines in Perl not yet published.  
All those fine details are explained there.


-- fxn


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Re: Newline error

[John W. Krahn]

Mr. Shawn H. Corey wrote:
> 
> $output_file =~ s/\r//g;
> # chomp only removes linefeed characters \n
> 
> # BTW, there is no such thing as a newline;
> # it is either a linefeed: \n ASCII LF 0x0A
> # or a carriage return: \r ASCII CR 0x0D

"\n" is inherited from the C programming language and is the newline escape
sequence.  On Unix and Unix-like systems the newline is equivalent to the
ASCII line feed character but on other systems it could be one or more
different characters.

http://en.wikipedia.org/wiki/Newline


John
-- 
use Perl;
program
fulfillment

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Re: Newline error

[Muma W.]

joseph wrote:

All,

Just like to ask for correction on what's wrong with my script it gives spit 
out this error when i run it.


Unsuccessful open on filename containing newline at disksize.pl line 8.
Can't open file No such file or directory

But it runs without this error whenever i feed it up when an existing file 
output by df-h.

ex:## open(FL,"path/toactual/file") or die "blabalha";
Does this mean it can't trap the output of  `df-h`?

Here's the script###

#!/usr/bin/perl

use strict;
use warnings;

chomp(my $output_file = `df -h`);



Df can return multiple lines. I'd suspect that your string $output_file
has several embedded newlines in it at this point. Chomp will only
remove that last (not embedded) newline.


open(FL,"$output_file") or die "Can't open file $!\n";
my @list;
my %disk;
my($label,$size,$use,$avail,$percent,$mounted,$partition,$usage);
while() {
 ($label,$size,$use,$avail,$percent,$mounted) = split(/\s+/, $_);
 push @list,$mounted,$percent;


You might not need the intermediate list:
$disk{$mounted} = $percent;


}

%disk =(@list);
delete $disk{"Mounted"};



foreach (sort keys %disk) {
   my $value = $disk{$_};
   print "\t $_ => $value \n";
}






I'd do it like this:

use strict;
use warnings;
use Data::Dumper;

my %disk;
for (`df -h`) {
next if ! m{/};
my($label,$size,$use,$avail,$percent,$mounted,$partition,$usage) =
split /\s+/, $_;
$disk{$mounted} = $percent;
}
print Dumper(\%disk);

__END__

You'll notice that the backticks operator (``), in a list context,
returns a list containing each line as a separate list element.

Since you only seem to need two elements from the list returned by
split(), you could change the two lines after the "m{/}" to this:

my @list = split /\s+/, $_;
$disk{$list[5]} = $list[4];

HTH




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Re: Newline error

[Mr. Shawn H. Corey]

On Tue, 2006-06-06 at 18:59 +0800, joseph wrote:
> All,
> 
> Just like to ask for correction on what's wrong with my script it gives spit 
> out this error when i run it.
> 
> Unsuccessful open on filename containing newline at disksize.pl line 8.
> Can't open file No such file or directory
> 
> But it runs without this error whenever i feed it up when an existing file 
> output by df-h.
> ex:## open(FL,"path/toactual/file") or die "blabalha";
> Does this mean it can't trap the output of  `df-h`?
> 
> Here's the script###
> 
> #!/usr/bin/perl
> 
> use strict;
> use warnings;
> 
> chomp(my $output_file = `df -h`);

$output_file =~ s/\r//g;
# chomp only removes linefeed characters \n

# BTW, there is no such thing as a newline;
# it is either a linefeed: \n ASCII LF 0x0A
# or a carriage return: \r ASCII CR 0x0D

> 
> open(FL,"$output_file") or die "Can't open file $!\n";

... or die "cannot open file '$output_file': $!\n";
# print out the contents so you can see exactly what it contains.

> my @list;
> my %disk;
> my($label,$size,$use,$avail,$percent,$mounted,$partition,$usage);
> while() {
>  ($label,$size,$use,$avail,$percent,$mounted) = split(/\s+/, $_);
>  push @list,$mounted,$percent;
> }
> 
> %disk =(@list);
> delete $disk{"Mounted"};
> 
> 
> 
> foreach (sort keys %disk) {
>my $value = $disk{$_};
>print "\t $_ => $value \n";
> }



-- 
__END__

Just my 0.0002 million dollars worth,
   --- Shawn

"For the things we have to learn before we can do them, we learn by doing them."
  Aristotle

* Perl tutorials at http://perlmonks.org/?node=Tutorials
* A searchable perldoc is at http://perldoc.perl.org/



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Re: Newline error

[John W. Krahn]

joseph wrote:
> All,

Hello,

> Just like to ask for correction on what's wrong with my script it gives spit 
> out this error when i run it.
> 
> Unsuccessful open on filename containing newline at disksize.pl line 8.
> Can't open file No such file or directory
> 
> But it runs without this error whenever i feed it up when an existing file 
> output by df-h.
> ex:## open(FL,"path/toactual/file") or die "blabalha";
> Does this mean it can't trap the output of  `df-h`?
> 
> Here's the script###
> 
> #!/usr/bin/perl
> 
> use strict;
> use warnings;
> 
> chomp(my $output_file = `df -h`);

`df -h` does not return a file name, it returns the same output as if you had
run the command 'df -h' on the command line.


> open(FL,"$output_file") or die "Can't open file $!\n";
> my @list;
> my %disk;
> my($label,$size,$use,$avail,$percent,$mounted,$partition,$usage);
> while() {

There are two basic ways to do what you want:

1.  for ( `df -h` ) { ... }

2.  open FL, 'df -h |' or die "Cannot open df pipe: $!";
while (  ) { ... }
close FL or warn $! ? "Error closing df pipe: $!"
: "Exit status $? from df";


>  ($label,$size,$use,$avail,$percent,$mounted) = split(/\s+/, $_);

You are only using two of the values so you can simplify that to:

   my ( $percent, $mounted ) = ( split )[ -2, -1 ];


>  push @list,$mounted,$percent;

You don't need the array, you can assign directly to the hash:

   $disk{ $mounted } = $percent unless $mounted eq 'Mounted';


> }
> 
> %disk =(@list);
> delete $disk{"Mounted"};



John
-- 
use Perl;
program
fulfillment

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Re: Newline error

[Xavier Noria]

On Jun 6, 2006, at 12:59, joseph wrote:

All,

Just like to ask for correction on what's wrong with my script it  
gives spit

out this error when i run it.

Unsuccessful open on filename containing newline at disksize.pl  
line 8.

Can't open file No such file or directory

But it runs without this error whenever i feed it up when an  
existing file

output by df-h.
ex:## open(FL,"path/toactual/file") or die "blabalha";
Does this mean it can't trap the output of  `df-h`?


Dealing with system commands (ls, ps, df, etc.) that way is usually  
much tricky than it looks. Normally one goes to CPAN and checks  
whether someone has done it right already. In that case one installs  
the module and writes an easy and robust script in 5 minutes.


For this particular problem delegate to Sys::Filesystem.

-- fxn




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Newline error

[joseph]

All,

Just like to ask for correction on what's wrong with my script it gives spit 
out this error when i run it.

Unsuccessful open on filename containing newline at disksize.pl line 8.
Can't open file No such file or directory

But it runs without this error whenever i feed it up when an existing file 
output by df-h.
ex:## open(FL,"path/toactual/file") or die "blabalha";
Does this mean it can't trap the output of  `df-h`?

Here's the script###

#!/usr/bin/perl

use strict;
use warnings;

chomp(my $output_file = `df -h`);

open(FL,"$output_file") or die "Can't open file $!\n";
my @list;
my %disk;
my($label,$size,$use,$avail,$percent,$mounted,$partition,$usage);
while() {
 ($label,$size,$use,$avail,$percent,$mounted) = split(/\s+/, $_);
 push @list,$mounted,$percent;
}

%disk =(@list);
delete $disk{"Mounted"};



foreach (sort keys %disk) {
   my $value = $disk{$_};
   print "\t $_ => $value \n";
}




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