Shell Programming and Scripting

perl -p -i -e 's/Mary/Joe/' test.txt

#!/usr/bin/perl -w
use strict;
use warnings;

my $file = 'test.txt';
open my $content, ">", $file or die("Could not open file. $!");

$content =~ s/Mary/Joe/g;

print $content $file;
close $content;

perl -p -i -e 's/Mary/Joe/' test.txt

perl -p -i -e 's/Mary/Joe/' test.txt test2.txt test3.txt

#!/usr/bin/perl
# -w removed from shebag since it does the same that use warnings

use strict;
use warnings;

my $file = 'test.txt';
open (my $content, "<", $file) or die("Could not open file. $!");

# read the content one line at a time
while ( $line = <$content> ) {
    $line =~ s/Mary/Joe/g;
    print "$line";
}

close $content;

#!/usr/bin/perl
# -w removed from shebag since it does the same that use warnings

use strict;
use warnings;
my $line;
my $file = 'test.txt';
open (my $content, "<", $file) or die("Could not open file. $!");

# read the content one line at a time
while ( $line = <$content> ) {
    $line =~ s/Mary/Joe/g;
    print "$line";
}

close $content;

#!/usr/bin/perl

use diagnostics;
use strict;
use warnings;

our $content;

open ($content, "<", "test.txt");
$content =~ s/Mary/Joe/g;
open ($content, ">", "test.txt");

close $content;

#!/usr/bin/perl

use diagnostics;
use warnings;
use strict;
 
my $src = 'test.txt';
my $des = 'test.txt';
my $line;
 
# open source file for reading
open(SRC,'<',$src) or die $!;
 
# open destination file for writing
open(DES,'>',$des) or die $!;
 
while($line = <SRC>){
$line =~ s/Mary/Joe/g;
   print $line $des;    
}
 
# always close the filehandles
close(SRC);
close(DES);

#!/usr/bin/perl

use strict;
use warnings;


open my $content_in, '<', "test.txt" or die("Could not open file. $!");
open my $content_out, '>', "test.tmp.txt" or die("Could not open file. $!");

while ( my $line = <$content_in> ) {
    $line =~ s/Mary/Joe/g;
    print $content_out $line;
}
close $content_in;
close $content_out;

unlink "test.txt";
rename "test.tmp.txt", "test.txt";

#!/usr/bin/perl

use strict;
use warnings;

my $sources = 'test.txt';

@ARGV = ($sources);
$^I = '.bak';

while (<>) {
    s/Mary/Joe/g;
    print;
}

#!/usr/bin/perl

use diagnostics;
use warnings;
use strict;
 
@ARGV = ('test.txt', 'test2.txt');

$^I = '.bak';

while (<>) {
    s/Mary/Joe/g;
    print;
}

$^I = '';

@ARGV = ("test.txt", 'test2.txt');

$^I = '';