Perl Script: searchone.pl

  Here's a simple Perl script named searchone.pl that searches a given data file for a specified pattern. This script takes two command-line arguments: the search pattern and the file name. It will read the file and print out lines that match the search pattern, similar to the behavior of the grep command. Perl Script: searchone.pl #!/usr/bin/perl use strict; use warnings; # Check if the correct number of arguments are provided if (@ARGV != 2) { die "Usage: $0 search-pattern search-file\n"; } my ($pattern, $file) = @ARGV; # Check if the file exists and is readable unless (-e $file && -r $file) { die "File '$file' does not exist or cannot be read.\n"; } # Open the file for reading open my $fh, '<', $file or die "Cannot open file '$file': $!\n"; # Search for the pattern in each line of the file while (my $line = <$fh>) { if ($line =~ /$pattern/) { print $line; # Print the matching line } } # Close the file handle close $fh; How to Use the Script 1. Save the Script: Copy the above code into a text file and save it as searchone.pl. 2. Make it Executable: You need to give execute permissions to your script. You can do this by running: chmod +x searchone.pl 3. Run the Script: You can run the script from the command line by providing a search pattern and a file name. For example: ./searchone.pl pop /etc/services ./searchone.pl imap /etc/services Explanation of the Script - The script starts by checking if exactly two arguments are provided. If not, it prints a usage message and exits. - It assigns the command-line arguments to $pattern and $file. - The script checks if the specified file exists and is readable. If not, it exits with an error message. - It opens the file for reading and uses a while loop to read through each line of the file. - Inside the loop, it checks if the line matches the given pattern using a regular expression. If it does, it prints the line. - Finally, it closes the file handle. Testing the Script To ensure that your script behaves like grep, you can test it against known patterns and files. For example, compare the output of your script with: grep 'pop' /etc/services grep 'imap' /etc/services Make sure to check both matching and non-matching patterns to validate that your script is functioning correctly. By following these instructions, you will have a fully functional Perl script that emulates a basic version of grep for searching patterns in files.      

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