How can i find a specific line in a file using Perl?

Question

I am new to Perl. I want to find a string in some file and then i want the whole line which contains the string.

Answer 1

if ( !open(LOGFILE, "<myfile.log") ) 
{
print "ERROR: failed to open myfile.log\n";}
else {   
while (<LOGFILE>){
if ($_ =~ /pattern/)
    {    print "found\n";
         break;
     }
}   
close (LOGFILE);
}

Answer 2

1. Open the file

2. Loop, while there are lines to read from the file

   2.1 Using regular expressions, check if the line matches the pattern: if ($line =~ /pattern/).

   2.2 If yes, print the string

3. Close the file.

Answer 3

perl -ne 'print if m/whatever/' file