MySandbox: PERL odds and sods

Dumping some of the PERL scripts that I had written from my home directory into this blog entry

Array:
array_count.pl

#!/usr/bin/perl -w

#
# This script simply gives the length of the array
#

@numbers = qw(one two three four);

$array_length = @numbers;

print "Array length = $array_length\n";

array_reversal.pl

#!/usr/bin/perl -w

#
# This script give an example of how an array is reversed in perl
#
@teams = qw(chelsea liverpool mancity arsenal);

foreach my $team (reverse @teams)
{
print ("$team \n");
}

Capture command line output:
mysqld_port.pl

#!/usr/bin/perl -w

#
# This script redirects the mysql infor from netstat into a file
#
open (MYHANDLE, "netstat -tulpn|");

open (OUTHANDLE, ">> mysql.out");

while(<MYHANDLE>) {
    if (/mysqld/) {
        print OUTHANDLE $_;
    }
}

close (OUTHANDLE);
close (MYHANDLE);

num_files.pl

#!/usr/bin/perl -w

#
# This scripts counts the number of files in the current directory
#

sub file_count {
    open (MYHANDLER,"ls -1 |");
    $count = 0;

    while (<MYHANDLER>) {
        $file = $_;
        chomp($file);
        if (-f $file) {
            $count = $count + 1;
        }
    }

    print "There are $count files in the directory\n";
}

file_count();

open_netstat.pl

#!/usr/bin/perl -w

#
# This script redirects the output of netstat into a file
#
open (MYHANDLE, "netstat -tupl|");

open (MYOUT, ">>mynetstat.txt");

while(<MYHANDLE>)
{
print MYOUT $_;
}

File IO:
check_logfiles.pl

#!/usr/bin/perl -w

#
# This script accepts log files as input and checks for the string 'connection
# accepted from'
#
while ($data = <>) {
        if ($data =~ /\bconnection accepted from\b/) {
                print "$data";
        }
}

get_nameserver.pl

#!/usr/bin/perl -w

#
# This function get the name server ip addresses from the resolv.conf file
#

sub get_nameserver {
    open(MYHANDLER, "/etc/resolv.conf") || die ("ERROR: unable to open file\n");

    while(<MYHANDLER>) {
        if(/nameserver\b/)
        {
            @ip_addr = split(/\s+/,$_);
            open(MYOUT,">>outfile");
            print OUT "$ip_addr[1]\n";
    }
   }
   close(MYHANDLER);
   close(MYOUT);
}

get_nameserver();

number_of_lines.pl

#!/usr/bin/perl -w

#
# This function asks the user to enter a file name
#
sub enter_filename {
    print "Enter a file name: ";
    $file_name = <STDIN>;
    chomp($file_name);
    return($file_name);
}

#
# This function counts the number of lines in the file
#
sub number_lines {
    $i = 0;
    $file_name = $_[0];
    if (-e $file_name) {
        open (MYHANDLER, $file_name) || die("ERROR: unable to open file";

        while (<MYHANDLER>)
        {
            $i=$i+1;
        }

        close(MYHANDLER);
        return($i);
    } else {
        print "File $file_name does not exist.\n";
    }
}

$user_file_name = enter_filename();
$number_of_lines = number_lines($user_file_name);

print "Number of lines in the file: $number_of_lines\n";

read_hosts.pl

#!/usr/bin/perl -w

$file_name = "/etc/hosts";

#
# This function returns host names and ip address from the /etc/hosts file
#

sub host_ipaddr {
    open(MYHANDLE,$file_name);

    while(<MYHANDLE>)
    {
        chomp;
        if (/^[0-9]/)
        {
            @fields = split(/\s+/,$_);
            print ("$fields[0] $fields[1]\n");
        }
    }
   close(MYHANDLE);
}

host_ipaddr($file_name);

read_passwd.pl

#!/usr/bin/perl -w

#
# This function reads the password file and outputs it onto the screen/stdout
#

sub read_passwd {
    open (FILEHANDLE, "/etc/passwd") || dir("ERROR: unable to open file\n");

    while ($name = <FILEHANDLE>)
    {
        chomp($name);
        print "$name \n";
    }

    close (FILEHANDLE);
}

read_passwd();

remove_blank.pl

#!/usr/bin/perl -w

#
# This script removed the blank lines from the file passed to it. The out
# gets displayed on the screen/stdout.
#

if (! defined $ARGV[0]) {
    usage();
} else {
    $my_file = "$ARGV[0]";
}

if (-e $my_file) {
    print ("File exists\n");
} else {
    print ("File does not exists.\n");
    exit 1;
}

open (MYHANDLER, $my_file) || dir("ERROR: unable to open file\n");

while(<MYHANDLER>) {
     if (/[^\s+]/) {
        print $_;
    }
}

close(MYHANDLER);

sub usage {
    print ("USAGE: .\/remove_blank.pl <file_name>\n");
    exit 1;
}

write_passwd.pl

#!/usr/bin/perl -w

#
# This function reads the password file and outputs it onto the file outfile.txt
#

sub write_passwd {
    open (FILEHANDLE, "/etc/passwd") || dir("ERROR: unable to open file\n");
    open (OUTFILE, ">outfile.txt") || dir("ERROR: unable to open file\n");

    while ($name = <FILEHANDLE>)
    {
        print OUTFILE $name;
    }

    close (FILEHANDLE);
    close (OUTFILE);
}

write_passwd();

Loops:
print_num.pl

#!/usr/bin/perl -w

print "Enter a number: ";
$my_num = <STDIN>;
chomp($my_num);

print_number($my_num);

sub print_number {
    $prtnum = $_[0];
    print "$prtnum\n";

    for ($i=$prtnum-1; $i >=0 ; $i--) {

        print_number($i);

    }
}

Match:
grep_user.pl

#!/usr/bin/perl -w

while (<>)
{
if (/oracle/)
{
print $_;
}
}

number_range.pl

#!/usr/bin/perl -w

sub user_interface {
    print "Enter a number between 1 to 9: ";
    $my_number = <STDIN>;
    chomp ($my_number);
    return $my_number;
}

sub print_number {
    my $my_number = $_[0];
    if (($my_number >= 1) && ($my_number <= 9))
    {
        print "The number entered is: $my_number\n";
    } else {
        print "The number $my_number is out of range.\n";
    }
}

$num_entered = user_interface();
print_number($num_entered);

single_digit.pl

#!/usr/bin/perl -w

$_ = 32;

if (/[0123456789]/)
{
print "Match: $_ \n";
}

Split:
greatest_number.pl

#!/usr/bin/perl -w

sub user_interface {
    print "Enter some numbers: ";
    $numbers = <STDIN>;
    chomp($numbers);
    return $numbers;
}

sub greatest_number {
    @number_array = split(/\s+/,$_[0]);
    $x = $number_array[0];

    foreach $i (@number_array) {
        if ($i > $x) {
            $x = $i;
        }
    }

    print "The greatest number is $x\n";
}

$num_entered = user_interface();
greatest_number($num_entered);

split_ipaddr.pl

#!/usr/bin/perl -w

$ip_addr = "129.40.71.195";

@addr = split(/\./,$ip_addr);

foreach $num (@addr) {
print "$num\n";
}

split.pl

#!/usr/bin/perl -w

#
# This script finds if user oracle exists in the /etc/passwd file
#
open (MYHANDLER,"/etc/passwd");

while (<MYHANDLER>)
{
    @fields = split(/:/,$_);
    $_ = $fields[0];
    if (/oracle/)
    {
        print "User oracle exists.\n";
        print "$_\n";
    }
}

String:
reverse.pl

#!/usr/bin/perl -w

$mystring = "hello";
$mylength = length($mystring);

@fields = split(//,$mystring);

for ($i=$mylength-1; $i>=0; $i--)
{
print $fields[$i];
}
print "\n";

strcmp.pl

#!/usr/bin/perl -w

sub user_interface {
    print "Enter the first string: ";
    $strs = <STDIN>;
    chomp($strs);
    return ($strs);
}

sub string_compare {
    print "string_compare function $_[0]\n";
    @strings = split(/\s+/,$_[0]);
    print "The strings after splitting: $strings[0] $strings[1]\n";

    $len_one = length($strings[0]);
    $len_two = length($strings[1]);

    if($len_one != $len_two)
    {
        print "The length of the strings is different\n";
    } else {
        print "The length of the strings is same\n";

        @first_array = split(//,$strings[0]);
        @second_array = split(//,$strings[1]);

        for ($i=0; $i < $len_one; $i++) {
            if ($first_array[$i] ne $second_array[$i]) {
                print "The words are different\n";
                exit 1;
            }
        }
        print "The words are the same\n";
    }
}

$my_strings = user_interface();
print "The strings to be compared are $my_strings\n";
string_compare($my_strings);
exit;

strcpy.pl

#!/usr/bin/perl -w

$orig_string = $ARGV[0];
print ("Original: $orig_string \n");
$final_string = $orig_string;

print ("Result: $final_string \n");

[root@isvx3 string_manipulation]# cat strcpy.pl
#!/usr/bin/perl -w

$orig_string = $ARGV[0];
print ("Original: $orig_string \n");
$final_string = $orig_string;

print ("Result: $final_string \n");

stringlen.pl

#!/usr/bin/perl -w

$myword = "silly me";

$mylen = length($myword);

print "Length = $mylen";

string_reversal.pl

#!/usr/bin/perl -w

$myword = "silly me";

$mylen = length($myword);

print "Length = $mylen";

upper_lower.pl

#!/usr/bin/perl -w

print "Enter a world: ";
$myword = <STDIN>;
chomp($myword);

$myword =~ s/\W.*//;

print "The word entered is: $myword \n";

user_exists.pl

#!/usr/bin/perl -w

$file = $ARGV[0];
if (-e $file) {

open(MYHANDLER, $file);

while(<MYHANDLER>)
{
    chomp;
    if (/\bHadoop\b/)
    {
        print "$_ \n";
    }
}
close(MYHANDLER);
} else {
    print "File $file does not exist\n";
}

wordcountmap.pl

#!/usr/bin/perl -w

while (<STDIN>) {
    chomp;
    @words = split(/\s+/,$_);
    foreach $w (@words) {
        print "$w\n";
    }
}

MySandbox

Monday, March 10, 2014

PERL odds and sods

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