Shell Programming and Scripting

CVR( 9) =   0.385E+05,  ! VEHICLE        
CVR(10) =   0.246E+05,  ! SAUCE
CVR(11) =   0.162E+03,  ! VEHICLE

#!/usr/local/bin/perl
use strict;
use warnings;
 
my $header = "Unnom_";
 
my @va = [111 222 333 444 555 666 777 888];
my @ma = [1 2 3 4 5 5a 6 7 8];
 
my $v;
my $m;
 
foreach $v (@va) {
  foreach $m (@ma) {
 
(need to get this value from file1 ex. 0.246E+05);
$extractedvalue =  (get number from /data/$m/$v/Nom_$v_$m_PUNCH)
 
system ("sed '2,10d' $m/$v/Nom_$v.ol.$m.input > $m/$v/$header$v.ol.$m.input"); #this creates a new file that has the first 2 lines of the $m/$v/Nom_$v.ol.$m.input file
 
# maybe a better way to do it would be to add this line to the added text (below) and remove the system sed command
P$WHAT PATH = '/data/$v.ol.$m.input', $
 
 
(need to add the following lines of text to the bottom of $m/$v/$header$v.ol.$m.input);
cat "
OBJECT    = A, B,   C, D, 1E+3,\n
CV(10) =  { PRM(5) = -1.0,}, \n
CVR(10)=   $extractedvalue,\n
$
"
>> $m/$v/$header$v.ol.$m.input #will this create this file if it doesn't exist? Can I create them above if the sed command is deleted?"
}
}

 
$ perl -lane 'if ($_=~/SAUCE/){$F[2]=~s/,//;print $F[2]}' inputfile
0.246E+05

Blah blah random text
 
random $text that has $$variables in it but I need to just be text
 
the above line should literally read "$text" and "$variables"
 
other $random text that i $need to evaluate variables
 
the above line should convert $random and $need to their respective values example 5 and 51
 
The variable $extracted_number - this number needs to be 0.246E+05

$
$
$ # Show the content of the file "file1". We'll make use of the fact that "CVR(10)" and "SAUCE"
$ # appear only once in the file.
$
$ cat file1
CVR( 9) =   0.385E+05,  ! VEHICLE
CVR(10) =   0.246E+05,  ! SAUCE
CVR(11) =   0.162E+03,  ! VEHICLE
$
$
$ # Show the Perl program
$
$ cat -n file1.pl
     1  #!perl -w
     2  use strict;
     3
     4  my $random = 5;
     5  my $need = 51;
     6  my $extracted_number;
     7  my $file = "file1";
     8
     9  # read the value of $extracted_number from "file1"
    10  open (FH, "<", $file) or die "Can't open $file for reading: $!";
    11  while (<FH>) {
    12    if (/^CVR\(10\)\s*=\s*(.*?),.*?SAUCE$/) {
    13      $extracted_number = $1;
    14      last;
    15    }
    16  }
    17  close (FH) or die "Can't close $file: $!";
    18
    19  # We have read the value of $extracted_number now; it will be used
    20  # while printing the string below
    21  my $str = <<"EOF";
    22  Blah blah random text
    23  random \$text that has \$\$variables in it but I need to just be text
    24  the above line should literally read "\$text" and "\$variables"
    25  other $random text that i $need to evaluate variables
    26  the above line should convert \$random and \$need to their respective values example 5 and 51
    27  The variable $extracted_number - this number needs to be 0.246E+05
    28  EOF
    29
    30  print $str;
$
$
$ # Execute the Perl program
$
$ perl file1.pl
Blah blah random text
random $text that has $$variables in it but I need to just be text
the above line should literally read "$text" and "$variables"
other 5 text that i 51 to evaluate variables
the above line should convert $random and $need to their respective values example 5 and 51
The variable 0.246E+05 - this number needs to be 0.246E+05
$
$
$

/^CVR\(10\)\s*=\s*(.*?),.*?SAUCE$/ =>
 
See if the current line matches the regular expression that:
 
^        : has at the beginning
CVF      : the characters "C", "V", "R", followed by
\(       : an open-parenthesis character (the escape character is necessary because we want Perl to consider its literal value)
10       : followed by the characters "1", "0", followed by
\)       : a close-parenthesis character (escaping is necessary because we want Perl to consider its literal value)
\s*      : followed by 0 or more occurrences of whitespace characters
=        : followed by the "=" character
\s*      : followed by 0 or more occurrences of whitespace characters
(.*?),   : followed by the shortest continuous sequence of characters that ends with
        the comma character (","); group and capture this shortest continuous
        sequence of characters in a variable called "$1". This "grouping and
        capturing" is achieved by the parentheses; note that they are not
        escaped here, because we want Perl to consider their special (and not literal) values here
.*?S     : followed by shortest continuous sequence of characters that is followed by the character "S"
AUCE     : followed by the characters "A", "U", "C", "E"
$        : thereby reaching the end of the line

(1)  The most well-known book on regexes is this one:
Mastering Regular Expressions, 3rd Ed by Jeffrey Friedl - 
Chapter 3: Overview of Regular Expressions Features and Flavors, Section "Lazy Quantifiers"
Chapter 4: The Mechanics of Expression Processing - entire chapter provides detailed information of backtracking, greediness and laziness
 
(2)  Jan Goyvaerts, the author of "Regular Expressions Cookbook", has a website on regular expressions, and he explains greediness/laziness over there:
http://www.regular-expressions.info/repeat.html
 
(3)  The online Perl documentation has a really good tutorial on regexes. The section "Matching Repetitions" explains this concept:
http://perldoc.perl.org/perlretut.html#Matching-repetitions