Pass argument through command line and popup if the user has not given the input

Question

The code below creates a file and accepts an input argument through the command line.

I want to do two things:

If the user forgot to enter the input on the command line, the system should give some sort of alert or message. Assume if I forgot to give an input argument, then the system should not proceed with the script execution.
Assume if the system tries to create the already existing file, at present we are managing with showing a message like "File already exists", but instead I want to ask something like "File already exists, are you sure you want to override? yes/no". If he answers yes, then simply override the existing one, else the system should ask for another input from the user.

#!/usr/local/bin/perl
#print "content-type: text/html \n\n";  #HTTP HEADER

$numArgs = $#ARGV + 1;
foreach $argnum (0 .. $#ARGV) {
   $GET_ALL_USER_INPUTS = "$ARGV[$argnum]\n";
}
@INPUT_ARR = split(/,/, $GET_ALL_USER_INPUTS);
$filename = "DD_WRITE_${INPUT_ARR[0]}.txt";
$GET_ARR_SIZE = scalar @INPUT_ARR;
$CLIENT_NAME = "T-sys";

$DD_CONTENT =  "Design Document  ${INPUT_ARR[0]} - ${CLIENT_NAME} :-\n";
$DD_CONTENT .= "--------------------------------------";
#get the  no length and generate dotted lines
for($i=0;$i<=length(${INPUT_ARR[0]});$i++){
    $DD_CONTENT .= "-";
}
$DD_CONTENT .= "--------------\n";
$DD_CONTENT .= "Database Details\n";

if (-e "${filename}") {
    print "File exists!";
    exit;
}
else {
    open(FILE, ">", "$filename") or die "Cannot open $filename - $!";
    print FILE "${DD_CONTENT}\n";
    close (FILE);
}

As this reads now, you have a desire, not a question. Please improve and tell us what specifically you have problems with. — daxim, Mar 10 '11 at 17:06
Thing is how to make alert while trying the already existing file creating, need to ask confirmation in the command line itself — Bharanikumar, Mar 10 '11 at 17:23

daxim · Answer 1 · 2011-03-10T18:50:43.177

2

I understand the question to be "How do I prompt a user?" because you do not know how to do that. I skip part 1 of the problem description because you already do know about exit.

First, you should replace your command-line argument handling with Getopt::Long. As it is written now, it is needlessly convoluted.

Getting input from a user at run-time is easy with ExtUtils::MakeMaker which already comes with the Perl distribution.

use ExtUtils::MakeMaker qw(prompt);
my $user_answer = prompt 'Okay to overwrite? ';
if ('y' eq $user_answer) { …

I see that you have commented out a piece of code about HTTP. If you intend to run this program under a CGI environment, prompting will not work as you would expect. On the Web, you need a different technology and control flow altogether.

edited Mar 10 '11 at 18:50

answered Mar 10 '11 at 17:58

daxim

39,270
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i installed the IO::Prompt, but its not working, getting Error like Can't locate IO::Prompt in @INC.... Error – Bharanikumar Mar 10 '11 at 18:18
Then you actually did not install it. See http://stackoverflow.com/questions/65865/whats-the-easiest-way-to-install-a-missing-perl-module – daxim Mar 10 '11 at 18:20
IO::Prompt does not work on Windows, see http://cpanratings.perl.org/dist/IO-Prompt#2957. I will edit the answer. – daxim Mar 10 '11 at 18:42

score 0 · Answer 2 · answered Mar 10 '11 at 17:51

0

The existence of a command line argument can be determined pretty easily:

if (exists $ARGV[0]) { do_stuff_with_args } else { die "No arguments!"; }

answered Mar 10 '11 at 17:51

caw

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or... `if (!(exists $ARGV[0])) { die "No arguments"; }` at the top of the script... – caw Mar 10 '11 at 17:52

Pass argument through command line and popup if the user has not given the input

2 Answers2

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