This procedure replaces all occurrences of 1 string with another in all
the arguments provided on the command line:

perl -pi -e 's/OLDSTRING/NEWSTRING/g' FILELIST

I am trying to write a script "substring.pl" that will do this, but can
be reused. Substring.pl should accept at least 4 arguments:

$OLDSTRING, $NEWSTRING, FILELIST (at least 2 files)

Questions:
1) How can I specify "display USAGE unless at least 4
arguments are given?
2) How can I run the substitution 's///g' counting from the third
argument onwards? I'd like the user to be able to call the script with a
fileLIST.

-------------------------------------------------------------------

Thanks in advance to all who reply. Could you please reply to this message

-------------------------------------------------------------------

The Script I have as of now:-

#!/usr/local/bin/perl

        print "*** Substituting string(s) in ", $#ARGV - 1, " files
***\n\n";
        }

    $OLDSTRING = $ARGV[0];
    $NEWSTRING = $ARGV[1];

    {
       $filename = $ARGV[$i];
       s/$OLDSTRING/$NEWSTRING/g

# I need help here ---^

    }

sub usage
{
        print "\nUSAGE: This script will replace all occurrences of 1 string with
another in all the files given on the command line...\n";
        print "EXAMPLE: substring OLDSTRING NEWSTRING FileList... \n\n";

        Bye,

 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
     Mukund Rao         !     http://www.*-*-*.com/ ~mrao
  Computer Science      !      Trinity College * BOX 700416
...............................................................
 Receptionist to physician: "The patient is in the middle of a
 magazine article and will see you soon, Doctor." --Readers Digest

Follow-up... The FileList can actually contain _one_ or more filenames; I
mistakenly specified "at least two..." in my request.

Thanks in advance to all who reply. Could you please reply to this message

        Bye,

 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
     Mukund Rao         !    http://shakti.trincoll.edu/~mrao
  Computer Science      !      Trinity College * BOX 700416
...............................................................
 Man to co-worker: "Of course it's not your day, Ernie! With five
 billion people on earth, do you realize what the chances are
 against it being 'your' day?" --Readers Digest

[mailed and posted]

This is untested, but hopefully it'll give you the general idea.

# you said at least 4 were required
&usage unless $ARGV[3];

print "Substiting $NEWSTRING for $OLDSTRING in $file\n";
        s/$OLDSTRING/$NEWSTRING/g;

On Wed, 5 Jun 1996, Mukund Rao wrote something resembling:

The rest is left as an exercise. :-)  Hint: See the perlrun(1) man page,
among others. Hope this helps!

-- Tom Phoenix            http://www.teleport.com/~rootbeer/