• FUNCTION:
  sub fName {
  my $arg1 = $_[0];
  my $arg2 = $_[1];
  my $alist = @_;
  my ($s, @a) = @_;
  $arg3 = …
  function_code…
  };
  &fName (87.65, 1082, @myA, $myS, “My String”, ‘c’, <OTHER PARAMETERS>);
  (NOTE: May omit ‘&’ from function call)

• ARRAY: my @a = ( ‘a’, ‘b’, ‘c’);
  print $a[1];

   

  displays a on the screen.

• HASH: my %h = ( ‘a’, ‘1′, ‘b’, ‘2′, ‘c’, ‘3′);
  OR
  my %h = ( a => ‘1′, b => ‘2′, c => ‘3′ );
  print $h{‘a’};

  displays 1 on the screen.

Pre-increment: –$v; ++$v;

• ! $v
  EX: if ( ! $x ) { print “Not $x”; }
• my $r = ~1001;
• my $mp = \@a;  // Create memory reference.
• + has no semantic effect.
• my $r = –$v;

• printf “%s”, $1 if $v =~ /Hello/;
• printf “%s”, $1 if $v !~ /Hello/;

• my $r = $v1 * $v2;
• my $r = $v1/ $v2;
• my $r = $v1 % $v2;
• ‘Beer’ x 3;  ‘BeerBeerBeer’

• my $r = $v1 + $v2;
• my $r = $v1 – $v2;
• my $strr = $str1 . $str2;

• my $r = $v1 << 3; # Shift 3 bits to LEFT
• my $r = $v1 >> 3; # Shift 3 bits to RIGHT

• if ( -r /path/file.xyz ) {
  print “File exists\n”;
  }
• if ( -d /path/file.syz ) {
  print “Directory exists\n”;
  }

• if ( $v1 <= $v2 ) {
  print “v1 is less then or equal to v2\n”;
  }
• if ($v1 ge $v2 ) {
  print “v1 is greater then or equal to v2\n”;
  }

• if ( $v1 == $v2 ) {
  print “v1 equals v2\n”;
  }
• if ( $str1 <=> $str2 ) {
  print “str1 and str2 contain exact same value.\n”;
  }
• <=> returns -1, 0, 1

• my $r = $v1 & $v2;
• my $r = 514 & 370;

• my $r = $v1 | $v2;
• my $r = $v1 ^ $v2;

• if ( $v1 && $v2 ) {
  ….
  }

• if ( $v1 || $v2 ) {
  …
  }

• foreach (1..100) {
  print;
  }

• ( $str1 <=> $str2 ) ? $v1 += 1 : $v1 += 2;

• my $r %= $v1;
• my $r -= $v1;

• “$va ||= 5″ reads if $va is FALSE (Is either: 0, undef, “”, ” ) assign 5 into $va.

• Used in hashes predominantly.
• %h = ( “a” => “1″,
  “b” => “2″,
  “c” => “3″,
  “d” => “4″
  );

• if ( not $var1 ) {
  print “var1not TRUE. IE var1 is FALSE.\n”;
  }

• if ( $v1 < $v2 and $v3 < $v4 ) {
  print “Ok, executing self destruct seq.\n”;
  }

• if ( $v1 < $v2 xor $v3 < $v4 ) {
  print “Ok, formatting your hard drive…\n”;
  }

• if ( ….. ) {
  print “Dont’ just sit there…do something!\n”;
  }

$mf = \$v;
print $$v;

my @a = ( 'a', 'b', 'c' );
my @ma = ( [ ‘a’, ‘b’, ‘c’ ], [ ‘d’, ‘e’, ‘f’ ], [ ‘g’, ‘h’, ‘i’ ] );
print $#ma;  # Print last index of array.  +1 = row count.
print $#[0]; # Print number of columns in first row.

# Array of Hashes
my @aoh = (
{k1 => ‘v1′, k2 => ‘v2′, d => ‘v3′},
{k1 => ‘v4′, k2 => ‘v5′, d => ‘v6′},
{k1 => ‘v7′, k2 => ‘v8′, d => ‘v9′},
);

# Assign value to a member
$aoh[0]{’k1′} = “v10″;

%h = (’user’ => ‘peanut’, ‘pass’ => ‘elephant’);

# Hash of Arrays
%hoa = (
k1 => [ “v1”, “v2” ],
k2 => [ “v3”, “v4”, “v5” ],
k3 => [ “v6”, “v7”, “v8” ],
);

# Assign value to a member
$hoa{k1}[0] = “v9″;

print “IF\n”;
} elsif ( …CONDITION… ) {

print “ELSIF\n”;

} else {

print “ELSE\n”;

}

print “UNLESS\n”;

} elsif ( …CONDITION… ) {

print “ELSIF\n”;

} else {

print “ELSE\n”;

print “Doing something..!”;

}

OR

do {

} while ( …EXPRESSION… );

print “Doing something..!”;

}

OR

do {

} until ( …EXPRESSION… );

}

for ( my $i = 0, my $j = 5, my $k = 9; $i < 100; $i++ ) {
print “You will see me 100 times.\n”;
…do something with $j…
…do something with $k…
}

}

EX: foreach $str(’abc’, ‘def’, ‘ghi’, ‘jkl’) { print $str”\n”; }

EX: foreach (1..10) { print $_”\n”; }  # Uses perl assumed default variable $_ if no explicit variable is specified.

EX: foreach $s1(@numbers) { print $s1″\n”; }  # NOTE: Anthing doe to $s1 effects the corresponding value in @numbers array however @numbers is not modified outside the scope of foreach.

EX: foreach (@lucky) { if (….) { print “You’re lucky!\n”; }

.

.

redo LABEL unless $1 == $2;

}

LABEL: {
$v1 > 5 && do {
print “v1 > 5\n”;
last LABEL;
};
$v1 > 4 && do {
print “v1 > 4\n”;
last LABEL;
};
$v1 > 3 && do {
print “v1 > 3\n”;
last LABEL;
}
}

.

.

.

TAG:

goto LABEL
.
.
.
.
LABEL:

This is good for testing code.  (IE when you want to skip over some code in your script so you can test a newly created module.)

# NOTE: The next statement normally causes control to go back to the top of the while loop, the while (…) statement.  In this case, because continue is used, next passes control to the continue block.

print if /string match/i;

# Declare files as binary (Use after ‘open’)
binmode ( FILEH_IN ); # R (binary read)
binmode ( FILEH_OUT );  # W (binary write)

# Used after ‘binmode‘ is called on file handle
while ( read(FILEH_IN, $buffer, 1024) ) {  # R (binary)
#… read 1024 bytes from FILEH_IN and store in $buffer…
}

# Redirect STDOUT to a file instead of terminal
open(BACKUP, “>&STDOUT“);
open(STDOUT, “>$FILE.xyz”);
.
.
open(STDOUT, “>&BACKUP“);

flock(FILEH, $lockType);  # See next table below for file lock types.
flock(FILEH, 2);  # Lock file
flock(FILEH, 8);  # Unlock file

seek(FILEH, BYTE_OFFSET, FPOS); # Move read pointer in file to FPOS position:

’seek’ FPOS (seek start location

tell (FILEH);  # Return current byte position in file
tell; # Return current byte positio of last file read.

eof (FILEH); # Check if EOF reached
eof;
print if /stringfound/ .. eof() # Print all lines between ’stringfound’ and EOF to FILEH.  ‘..’ is range operator.