Display file contents based on line number

Write a Perl program to display contents of the file in sorted order(ascending) based on line numbers given via command-line arguments. Note that the line numbers can be in any order and throw an error if the line number is large.

Syntax: perl Filename.pl File_to_be_read.abc x y z Here, Filename.pl is the name of the file that contains the perl script File_to_be_read.abc is the name of the file which is to be read. This file can be of any type. Ex- text, script, etc. x y z are the line numbers which are to be printed.

Approach: Sort the line numbers excluding the first argument which is file name. Once sorted read whole content of the file into an array using single statement (my @file = <FNAME>). Now loop through the sorted line numbers and display the file content by passing line number as index to file array like (print "$file[$var-1]\n";). Example 1: Consider a file Hello.txt

Perl

#!/usr/bin/perl
use warnings;
use strict;
 
# Check if line numbers are given as an input
if (@ARGV < 2)
{
    die "usage: pick file_name line_no1 line_no2 ...";
}
 
open FNAME, $ARGV[0] or die "cannot open file";

# Exclude the first argument 
# for sorting line numbers
shift (@ARGV); 
my @line_numbers = sort { $a <=> $b } @ARGV; 
 
# Read whole file content into an array 
# and removes new line using chomp()
chomp (my @file = <FNAME>);
 
foreach my $var (@line_numbers) 
{
    if ($var> $#file)
    {
        print "Line number $var is too large\n";
        next;
    }
    print "$file[$var-1]\n";
}
close FNAME;

Output:

Example 2: Reading the same script file

Perl

#!/usr/bin/perl
use warnings;
use strict;
 
# Check if line numbers are given as an input
if (@ARGV < 2)
{
    die "usage: pick file_name line_no1 line_no2 ...";
}
 
open FNAME, $ARGV[0] or die "cannot open file";

# Exclude the first argument 
# for sorting line numbers
shift (@ARGV); 
my @line_numbers = sort { $a <=> $b } @ARGV; 
 
# Read whole file content into an array 
# and removes new line using chomp()
chomp (my @file = <FNAME>);
 
foreach my $var (@line_numbers) 
{
    if ($var> $#file)
    {
        print "Line number $var is too large\n";
        next;
    }
    print "$file[$var-1]\n";
}
close FNAME;

Output:

If the line number passed is not in the file:

Display file contents based on line number

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