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Troll wrote:
> Now time for some stupid Qs: > > Let's say that the data I have is in a file called employees. > How can I call this file so that I can parse it? > > 1) Can I do: > @HRdata = `cat employees`; > while (<@HRdata>) { The above is considered bad practice, especially if the file is large. Why read the entire file into memory when you can read, process, and discard a line at a time..? To open and read a file: open (FIN, '<employess') || die "blah blah blah..."; while (<FIN>) { } > > > 2) With regard to the HEADING sections, the script has to be able to > recognise the different sections by the following rules: > # there's a blank line > before each heading > HEADING 1 # this is the name of the heading - > this is a string with a special character and a blank space as part of it > ColumnA ColumnB ColumnC # these are the column names - these are > strings which also can inlude a blank space if they have 2 or more words > ******* # a sort of an underlining > pattern > while (<FIN>) { if ( /^$/ ) { # this is a blank line, don't do anything } elsif ( /HEADING (\.+)/ ) { # this is a heading, with the heading name in $1 } elsif ( (($name, $sex, $status, $age) = /(\s+) (\s+) (\s+) (\d+)/) == 4 ) { # this line contains three words and a number, do whatever # (I'm not really sure if this will work. My Linux box is # down and I have no way of testing.) } } # end of while(<FIN>) > I guess this is to make sure that one does not include any silly heading > data as part of the arrays created and the parsing only takes place on > 'real' data. Can you pls advise? Or do you need more info? I'm more in > favour of creating separate 'if' loops due to my 'newbie' status. I'll get > lost otherwise... > "if loops"...? How does one make an if loop? > Thanks. > > > > "Troll" <> wrote in message > news:uRK4b.77094$... > >>Wow. I don't know how you get the time to respond to my queries in such >>detail. It is greatly appreciated. >>I just came back from work and it's like 2:30 am so I'll crash out soon > > and > >>have a closer read tomorrow [especially of the HEADINGS part]. >> >>With the push @array stuff I actually got to this today in my readings. I >>saw an example of appending an array onto another array with a push and I >>was wondering if we could just substitute a $variable for one of the > > arrays. > >>I'm glad you confirmed this.  >> >>I was also wondering if doing this at the beginning of the script: >> >>my (%names, %sexes, %depts, %m_statuses, %ages) # declaring things >>locally >> >>would be considered bad practice. I thought that one should declare things >>as my ( ) if one is using things within a loop so as not to impact > > anything > >>external to the loop. But if one uses variables/arrays both within and >>outside the loops, should we then still declare stuff as my ( )? >>Maybe I'm just confused about my ( )... >> >>Greg, if you could possibly keep an eye on this thread for the next few > > days > >>I would be very much in your debt. Your help has been invaluabe so far in >>allowing me to visualise quite a few things. >> >>Thanks very much. >> >> >>"Ga Mu" <> wrote in message >>news:uRJ4b.147542$ .net... >> >>>Troll wrote: >>> >>>>Thanks again ! >>>> >>>>1) >>>>Sorry for being too vague. With regard to the HEADINGS they separate >> >>blocks >> >>>>of data. But because the column names will be different [data is >> >>different] >> >>>>then I'm not quite sure I could use: >>>>$names{$heading}{$name}++; >>>> >>>>So I'm looking at creating separate my () definitions for each HEADING >> >>and >> >>>>just wanted to confirm how to jump out of one HEADING loop and start >> >>with >> >>>>the next. >>>> >>>>For example, under HEADING 1 we have these columns: >>>>Name, Sex, Dept, M_Status, Age >>>> >>>>and under HEADING 2we have: >>>>Address, Phone#, Mobile#, Salary >>>> >>>>So at the beginning of the script I would have >>>>my (%names, %sexes, %depts, %m_statuses, %ages) >>>>my (%addresses, %phones, %mobiles, %salaries) >>>>#then I have my while (<>) and parsing here >>>>#I have my output at the end >>>> >>>>Is that a little more clearer? >>> >>>Yes. Much clearer. There are a couple of different ways you could do >>>this. One is to use a single loop that reads through the file and uses >>>a state variable (e.g., $heading) to keep track of where you are in the >>>parsing process. The other is to have a separate loop for each heading. >>> Again, six of one, half a dozen of another. It's more a matter of >>>preference than anything else. >>> >>>An example of the first approach: >>> >>>my $heading = 'initial'; >>>my $fin_name = '/usr/local/blah/blah/blah'; >>>open FIN,$fin_name || die "Can't open $fin_name\n"; >>> >>>while (<FIN>) { >>> >>> # check for a new heading >>> # I am assuming single word heading names >>> if ( /HEADING (\S+)/ { >>> >>> $heading = $1; # set $heading equal to word extracted above >>> >>> # take appropriate action based on the heading we are under >>> >>> } elsif ( $heading eq 'NAMES' ) { >>> >>> ( $name, $sex, $dept, $m_status, $age ) = >>> /(\w+) (\w+) (\w+) (\w+) (\d+)/; >>> >>> # update counts, append to lists, etc... >>> >>> } elsif ( $heading eq 'ADDRESSES' ) { >>> >>> # I am assuming the address field is limited to 30 characters >>> # here: >>> ( $address,$phone, $mobile, $salary ) = >>> /(\.{30}) (\S+) (\S+) (\d+)/; >>> >>> # update counts, append to lists, etc... >>> >>> } >>> >>>} >>> >>> >>>And the second approach: >>> >>>my $heading = 'initial'; >>>my $fin_name = '/usr/local/blah/blah/blah'; >>>open FIN,$fin_name || die "Can't open $fin_name\n"; >>> >>># scan for first heading >>>while ( <FIN> && ! /HEADING NAMES/ ); >>> >>># parse the names, etc... >>>while ( <FIN> && ! /HEADING ADDRESSES/ ) { >>> >>> ( $name, $sex, $dept, $m_status, $age ) = >>> /(\w+) (\w+) (\w+) (\w+) (\d+)/; >>> >>> # update counts, append to lists, etc... >>> >>> >>># parse the addresses, etc... >>># for brevity , I am assuming only two headings >>>while ( <FIN> ) { >>> >>> ( $address,$phone, $mobile, $salary ) = >>> /(\.{30}) (\S+) (\S+) (\d+)/; >>> >>> # update counts, append to lists, etc... >>> >>>} >>> >>> >>>> >>>>2) >>>>With my last question regarding the printing of the names of single >> >>people, >> >>>>if we include a print statement in the parsing loop would that give us >>>>something like: >>>>Pete is single. >>>>John is single. >>>>while the parsing is still running? >>> >>>Yes. >>> >>> >>>>What I'm after is hopefully feeding that output into something else >>>>[@array?] which can then print a list of the names [line by line] at > > the > >>end >> >>>>of the script, something like: >>>>#this is the output structure >>>>Number of Petes = >>>>Number of Males = >>>>Singles are: >>>>Pete >>>>John >>>>Number of Salespeople = >>>> >>>> >>>>Does this make sense? >>>> >>> >>>Yes. It would be easy to create a list/array of, e.g., single people. >>>Prior to the loop, declare the array. Within the loop, test each person >>>for being single. If they are, push them onto the list: >>> >>># prior to your parsing loop, declare array @singles: >>> >>>my @singles; >>> >>># within your parsing loop, after parsing out name, status, etc.: >>> >>>if ( $m_status eq 'Single' ) push @singles,($name); >>> >>># after loop, to print the list of singles: >>> >>>print "Single persons:\n"; >>>foreach $single_person ( @singles ) print " $single_person\n"; >>> >>> >>>Greg >>> >> >> > > |
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Thanks again
Will I get these errors: Use of uninitialized value in print at ./netstat.pl line 16, <NET> line 1. Use of uninitialized value in print at ./netstat.pl line 17, <NET> line 1. Use of uninitialized value in print at ./netstat.pl line 18, <NET> line 1. ....etc if an undefined value is passed, for example, to $UDP4localaddress? Because if that's the case then all I need to do is to make sure that whatever I'm passing as part of the m()// is correctly split and defined as a string, digit, word etc, yes? "Ga Mu" <> wrote in message news:SM25b.251663$cF.79266@rwcrnsc53... > Troll wrote: > > Greg, > > I decided to give you a glimpse at the code itself so as to make it clearer. > > Just be aware that the variable/array names have changed but the general > > idea is the same. > > The hash errors refer to the variables in the increment section. > > > > #!/usr/bin/perl -w > > > > open(NET, "netstat|") || die ("Cannot run netstat: $!"); > > > > my(%UDP4localaddresses, %UDP4remoteaddresses, %UDP4states); > > > > $UDP4localaddress = '0'; > > $UDP4remoteaddress = '0'; > > $UDP4state = '0'; > > > > Why are you doing this (above)? This is initializing three variables to > zero. These three variables have nothing to do with the three variables > of the same name in the while loop. > > > $UDP4localaddresses = '0'; > > $UDP4remoteaddresses = '0'; > > $UDP4states = '0'; > > > > Why are you doing this (above)? This is initializing three scalars to > zero. These three scalars have the same name, but have nothing else to > do with the hashes of the same name. > > > $UDP4localaddresses{$UDP4localaddress} = '0'; > > $UDP4remoteaddresses{$UDP4remoteaddress} = '0'; > > $UDP4states = ($UDP4state} = '0'; > > > > Instances of hash keys are automatically initialized to zero. That is > what makes them perfect for counting occurences of unknown words, > numbers, etc. And even if you had to initialize them, you are > initilizing $UDP4localaddresses{0} to zero. > > > while (<NET>) { > > my($UDP4localaddress, $UDP4remoteaddress, $UDP4state)= > > /(\s+) (\s+) (\s+)$/; > > > > #increments start here > > $UDP4localaddresses{$UDP4localaddress}++; > > $UDP4remoteaddresses{$UDP4remoteaddress}++; > > $UDP4states = ($UDP4state}++; > > If the increments above are failing, it is probably because your m// is > failing and one or more of the keys (variable inside the {}) are > undefined. Try putting a print statement before the increments and > print each of the variables you are extracting, then play with the > regular expression until you get values for ALL of them. > > > } > > > > #here comes the output > > > > > > Can you pls criticise my futile attempt to get this going? As one can see, > > I'm not that clear on initializations... > > > > > |
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Troll wrote:
> Thanks again > > Will I get these errors: > Use of uninitialized value in print at ./netstat.pl line 16, <NET> line 1. > Use of uninitialized value in print at ./netstat.pl line 17, <NET> line 1. > Use of uninitialized value in print at ./netstat.pl line 18, <NET> line 1. > ...etc > > if an undefined value is passed, for example, to $UDP4localaddress? > Because if that's the case then all I need to do is to make sure that > whatever I'm passing as part of the m()// is correctly split and defined as > a string, digit, word etc, yes? > Exactly. Experiment with your re in the m// until you get values. |
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Troll wrote:
> Thanks again. No reading files into memory from now on [unless necessary] > > The data will actually be read from stdin in the form of > $ netstat | netstat.pl > or > $ netstat.pl < netstat > > Will something like this suffice? > #!/usr/bin/perl -w > while (<STDIN>) { STDIN is the default file handle, so all you need is: while (<>) { } >>"if loops"...? How does one make an if loop? > > What I meant here is that I'll create 4 separate 'if' sections [with their > own elsif branches], one for each HEADING section [there are 4 of them]. > So I think I meant 'if' statements...is that better or I am still confusing > my terminology? Makes more sense... |
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Looks like I had some typos there but after correcting them it's still a no
go  /^(\w+) (\s+)/; was changed to /^(\w+)(\s+)(\S+)(\s+)(\S+)/; # looking for word(s), 1 or more spaces, non-space(s), space(s), non-space(s) Still get the same output tho: #output section TCP = 6 # all is correct here Use of uninitialized value in concatenation (.) or string at... # error time - this refers to the 2nd print statement RecvQ = # this is blank What am I missing? "Troll" <> wrote in message news:%En5b.80452$... > OK, I had some luck getting the first value incremented but no more. > > Version which works: > ***************** > if (/tcp/) { > my($Proto)= > /^(\w+)/; > $Protos{$Proto}++; > } > print "TCP = $Protos{'tcp'}\n"; > > #output section > TCP = 6 # all is correct here > > > Version which does not work: > ********************** > if (/tcp/) { > my($Proto, $RecvQ)= > /^(\w+) (\s+)/; > $Protos{$Proto}++; > $RecvQs{$RecvQ)++; > } > print "TCP = $Protos{'tcp'}\n"; > print "RecvQ = $RecvQs{'0'}\n"; > > #output section > TCP = 6 # all is correct here > Use of uninitialized value in concatenation (.) or string at... # error > time - this refers to the 2nd print statement > RecvQ = # this is blank > > I have tried reading the second parameter as a (\s+) and as a (\d+) with no > luck. If you run netstat you will probably see that all items in the RecvQ > column are 0. > What have I done wrong now? > > Can a number of whitespaces be represented by: > /^(\w+) (\s+)/; # this is a word followed by some spaces followed by a > string > or is the above only ONE whitespace? > > |
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