Re: Newline error
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 -- To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED] http://learn.perl.org/ http://learn.perl.org/first-response
Re: Newline error
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(FL) {
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 ( FL ) { ... }
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
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Re: Newline error
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,$usage);
while(FL) {
($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
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,$usage);
while(FL) {
($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 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 -- To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED] http://learn.perl.org/ http://learn.perl.org/first-response
Re: Newline error
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 = FH) {
# 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
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,$usage);
while(FL) {
($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 [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(FL) {
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 ( FL ) { ... }
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 (Closed)
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,$usage);
while(FL) {
($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
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 = FH) {
# 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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