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System call fro Perl script

tester_V
Novice

Nov 18, 2017, 11:11 PM

Post #1 of 8 (6448 views)

System call fro Perl script	Can't Post

Quick question. How one can call execute Perl script from another Perl script.
The system call some how fails.

Laurent_R
Veteran / Moderator

Nov 19, 2017, 1:03 AM

Post #2 of 8 (6446 views)

Re: [tester_V] System call fro Perl script [In reply to]	Can't Post

Hi,

You have to show how you do it, because it works to call Perl from a Perl script with a system call.

As an example, I have here a Perl one-liner which calls the Schwartzian Transform script we discussed yesterday:

Code

$ perl -E 'say "foo"; system ("perl schwartz3.pl"); say "bar";' 
foo 
Rbck_flow_log.2017-10-01.1 
Rbck_flow_log.2017-10-01.2 
Rbck_flow_log.2017-10-01.3 
Rbck_flow_log.2017-10-01.4 
Rbck_flow_log.2017-10-01.10 
Rbck_flow_log.2017-10-01.12 
Rbck_flow_log.2017-10-01.13 
bar

Having said that, this may not be a very good idea and there may be a better way to do what you want. Please explain what you're trying to achieve.

(Since you're stuck with version 5.8 of Perl, you'll have to replace "-E" with "-e" and "say" with "print" and add line ends. If you're on Windows, you also need to change single quotes with double quotes and vice versa.)

tester_V
Novice

Nov 19, 2017, 1:41 AM

Post #3 of 8 (6443 views)

Re: [Laurent_R] System call fro Perl script [In reply to]	Can't Post

Hi Lauren,
I decided to try PM modules you guys suggested on a PC that has internet access and have to tell you those modules making life much easier.
Anyway, I installed <Sort::Naturally> module and a <Tie::File >and it is working amazingly well.
There is a little problem with the <Tie::File > part of the code,
It fails to execute (remove last line from a file) but if I ran it separately it is working fine. I thought maybe it is a good idea to make a separate script and just call it from the main script.
I’m using the same log files for processing.
Here is code that does not work.

Code

#!/usr/local/bin/perl 
 use strict   ; 
 use warnings ; 
 use File::Copy; 
  use Sort::Naturally ; 
 
 
       my $low         = "C:/Sixshot_logs/Flow.txt" ;          
       my $flow_sorted = "C:/Sixshot_logs/Flow-Sorted.txt" ;               
 
 
      open (my $flow_sorted_fh,'>',$flow_sorted) or die "Cannot open $flow_sorted $!"   ;       
 
      open (my $low_fh, '<', $low) or die $!;     
      my @file_list = <$low_fh>;            
 
      close $low_fh; 
  
      my @list = nsort (@file_list) ; 
     
      print $flow_sorted_fh "@list \n"     ;    
       
      close $low_fh ; 
      close $flow_sorted_fh    ; 
       
       use Tie::File ; 
       use Tie::Array;   # Have to use this use Tie::Arrey ## 
        
            my $cleand_Flow_f = "C:/Sixshot_logs/Flow-Sorted.txt" ;  
               tie my @lines_c, 'Tie::File', $cleand_Flow_f  or die "can't update $cleand_Flow_f: $!"; 
         delete $lines_c[-1]; 
 
      exit  ;

Laurent_R
Veteran / Moderator

Nov 19, 2017, 2:43 AM

Post #4 of 8 (6441 views)

Re: [tester_V] System call fro Perl script [In reply to]	Can't Post

Don't do it this way, this is much too complicated.

It is much easier and simpler to remove the last record from your @list array before writing it to the output file (or to write to the output file everything but the last item.

tester_V
Novice

Nov 19, 2017, 10:22 AM

Post #5 of 8 (6429 views)

Re: [Laurent_R] System call fro Perl script [In reply to]	Can't Post

And how to do that?
Googling this topic suggests very complicated code for that.
What you would suggest?

Thank you?

tester_V
Novice

Nov 19, 2017, 10:33 AM

Post #6 of 8 (6427 views)

Re: [tester_V] System call fro Perl script [In reply to]	Can't Post

I found it in Google, I "pop" the array list.
IT is working.
Here is the code:

my $filename = "C:/Sixshot_logs/Flow.txt" ;
my $fcopy = "C:/Sixshot_logs/Flow-Copy.txt" ;
my $flow_sorted = "C:/Sixshot_logs/Flow-Sorted.txt" ;
copy $filename, $fcopy or die "Cannot open $filename $!" ;

open (my $flow_sorted_fh,'>',$flow_sorted) or die "Cannot open $flow_sorted $!" ;

open (my $filename_fh, '<', $filename) or die $!;
my @file_list = <$filename_fh>;
my @list = nsort (@file_list) ;
print "@list \n" ;
pop @list;
print "@list \n" ;
print $flow_sorted_fh "@list \n" ;

close $flow_sorted_fh ;
close $filename_fh ;

Code

Laurent_R
Veteran / Moderator

Nov 19, 2017, 10:34 AM

Post #7 of 8 (6427 views)

Re: [Laurent_R] System call fro Perl script [In reply to]	Can't Post

Just one line of code to be added in order to remove the most recent item from the array:

Code

# ... 
my @list = nsort (@file_list);  
my $last_item = pop @list; # last item now removed from @list

or not printing the last item into the file:

Code

my @list = nsort (@file_list);  
print $flow_sorted_fh "@list[0..$#list-1] \n";

tester_V
Novice

Nov 19, 2017, 10:55 AM

Post #8 of 8 (6425 views)

Re: [Laurent_R] System call fro Perl script [In reply to]	Can't Post

Laurent, thank you for the code and a little education.
I appreciate it and I'm sure other appreciate it too.

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