You can change the number of elements in an array simply by changing the value of the last index of/in the array $#array. In fact, if you simply refer to a non existent element in an array perl extends the array as needed, creating... Read More

combination. /([0-255])(.)$11$11$1/; Read More

Type globs are another integral type in perl. A typeglob`s prefix derefrencer is *, which is also the wild card character because you can use typeglobs to create an alias for all types associated with a particular name. All kinds of... Read More

qw is a construct which quotes words delimited by spaces. use it when you have long list of words that are nto quoted or youjust do not want to type those quotes as youtype out a list of space delimited words. like @a = qw(1234) which is like @a=("1"... Read More

@ISA ->  each package has its own @ISA array. this array keep track of classes it is inheriting. ex: package child; @ISA=( parentclass); @EXPORT this array stores the subroutins to be exported from... Read More

The symbol that starts all scalar variables is called a prefix dereferencer. The different types of dereferencer are. (i) $-Scalar variables (ii) %-Hash variables (iii) @-arrays (iv) &-subroutines (v) Type globs-*myvar... Read More

There are a number of ways to dereference a reference. Using two dollar signs to dereference a scalar. $original = $$strref; Using @ sign to dereference an array. @list = @$arrayref; Similar for hashes Read More

Put -00 on your #! line, like this:         #!/usr/bin/perl -00 -w Read More

length() is a built-in prototyped as sub length($), and a scalar prototype silently changes aggregates into radically different forms. The scalar sense of a hash is false (0) if it’s empty, otherwise it’s a string... Read More

&myvariable is calling a sub-routine. & is used to identify a sub-routine. Read More

. Because y is a kind of quoting operator. The y/// operator is the sed-savvy synonym for tr///. That meAns y(3) would be like tr(), which would be looking for a second string, as in tr/a-z/A-Z/, tr(a-z)(A-Z), or tr[a-z][A-Z]. Read More

Perl keeps track of your variables, whether dynamic or otherwise, and doesn’t free things before you’re done using them. Read More

@solution = sort {lc $a comp lc$b } @arr Read More

perl -p -ibak -e ’s/search_str/replace_str/g’ filename Read More

Terms have the highest precedence in perl. Terms include variables, quotes, expressions in parenthesis etc. List operators have the same level of precedence as terms. Specifically, these operators have very strong left word precedence Read More

0 A defined (but false) 0 value is the proper indication of the end of file for read() and sysread(). Read More

use XYZ my $objref =XYZ -> new() OR, bless $objref, ’XYZ’ Read More

swap -l -> displays swap usage prstat -> examines all active processes on the system and reports statistics based on the selected output mode and sort order vmstat -> reports information about processes, memory,... Read More

Die prints out stderr message in the terminal before exiting the program while exit just terminate the program without giving any message. Die also can evaluate expressions before exiting. Read More

CGI and DBI. CGI(Common Gateway Interface) because we do not need to worry about the subtle features of form processing. Read More

In Perl it is an infix dereference operator. for array subscript, or a hash key, or a subroutine, then the ihs must be a reference. can also be used as method invocation Read More

@ISA -> each package has its own @ISA array. this array keep track of classes it is inheriting. ex: package child; @ISA=( parentclass); @EXPORT this array stores the subroutins to be exported from a module. @EXPORT_OK this array stores the... Read More

perl -e -d 1 PerlConsole Read More

${var} is the lexical variable $var, and ${"var"} is the dynamic variable $var. Note that because the second is a symbol table lookup, it is disallowed under `use strict "refs"’. The words global, local, package, symbol table, and dynamic all... Read More

To run the date command from a Perl program, and read the output of the command, all you need are a few lines of code like this: open(DATE, "date|"); $theDate = ; close(DATE); The open() function runs the external date command, then opens a file... Read More

open(IN, ") { chomp; $hash_table{$_} = 0; } close IN; print "$_ = $hash_table{$_} " foreach keys %hash_table; Read More

When your caller was in the middle for a while(m//g) loop The /g state on a global variable is not protected by running local on it. That’ll teach you to stop using locals. Too bad $_ can’t be the target of a my() -- yet. Read More

Use : 1. The method is used only for the modules(only to include .pm type file) 2. The included objects are varified at the time of compilation. 3. No Need to give file extension.   Require: 1. The method is used... Read More

you can use the following shell command in your perl script .  `cat filename|tail -10f ;`   This may not be accepted as well. But this can be done in numerous ways ! One way is here : ... Read More

require loads the code at run time. if the require file is not listed in the directory it produces an fatal error. Read More

It provides a GUI Read More

if the code inside a page gets too big, or if you want to use it elsewhere, you can cut it out, make it into a Java class, and invoke it from anywhere in your application (even not from a page). With Perl, you’re stuck inside the... Read More

Short for LAN on motherboard. The term refers to a chip or chipset capable of network connections that has been embedded directly on the motherboard of a desktop, workstation or server. Instead of requiring a separate network interface... Read More

prtdiag -v -> Shows mem, cpu, Power supply, add-on cards info, LEd status iostat -En -> Shows disk status.(look for hard error) /var/adm/messages -> Logs most commont failures and the entire system events ... Read More

Perl is a powerful free interpreter. Perl is portable, flexible and easy to learn. Read More

Here’s a simple technique to process each element in a hash: #!/usr/bin/perl -w %days = ( ’Sun’ =>’Sunday’, ’Mon’ => ’Monday’, ’Tue... Read More

perl -pi.bak -e ’s/ /,/g’ myfile.txt What is the easiest way to download the contents of a URL with Perl? Once you have the libwww-perl library, LWP.pm installed, the code is this: #!/usr/bin/perl use LWP:... Read More

Many. For example ’this is a string’ can be expressed in: "this is a string" qq/this is a string like double-quoted string/ qq^this is a string like double-quoted string^ q/this is a string/ q&... Read More

Use this function:         sub clear_the_screen {           print $ x 1_000_000;         } Read More

        %sorted = sort {$a <=> $b} %hash; Read More

You need to use a data structure that is more suited to your problem. 2-D Arrays, being rectangular, can be difficult to sort. If you instead use a triangular data structure, such as a heap, you need only hold it with the point downward,... Read More

You have to maintain a structure to store the line number and the size of the file at that time eg. 1-10bytes, 2-18bytes.. you have a counter to increase the number of lines to find out the number of lines in the file. once you are... Read More

The three different ways to empty an array are as follows 1) You can empty an array by setting its length to a negative number. 2) Another way of empting an array is to assign the null list (). 3) Try to... Read More

It has been said that all programs advance to the point of being able to automatically read mail. While not quite at that point (well, without having a module loaded), Perl does at least automatically send it. Read More

Use: 1. the method is used only for modules (only to include .pm type file) 2. the included object are verified at the time of compilation. 3. No Need to give file extentsion. Require: 1. The method is used for both libraries ( package ) and modules... Read More

’chop’ functiononly removes the last character completely ’from the scaler, where as ’chomp’ function only removes the last character if it is a newline. by default, chomp only removes what is currently defined as the ... Read More

it is a symbolic link to link one file name to a new name. so lets say we do it like file1-> file2, if we read file1, we end up reading file2 Read More

System calls "traditionally" returns 9 when successful and 1 when it fails. system (cmd) or die "Error in command" Read More

Q:  #create directory if not there if (! -s "$temp/engl_2/wf"){ System "mkdir -p $temp/engl_2/wf"; } if (! -s "$temp/backup_basedir"){ system "mkdir -p $temp/backup_basedir"; } ${pack_2} = -M "${temp}/engl_2/wf/${wf_package_name}.data"; $... Read More

 Pack Converts a list into a binary representation. Takes an array or list of values and packs it into a binary structure, returning the string containing the structure It takes a LIST of values and converts it into a string. The string... Read More

through push() and shift() function. push adds the element at the last of array and shift() removes from the beginning of an array. Read More

Grep is used with regular expression to check if a parituclar value exist in an array. it returns 0 it the value does not exists, 1 otherwise. Read More

You have to maintain a structure to store the line number and the size of the file at that time eg. 1-10bytes, 2-18bytes.. you have a counter to increase the number of lines to find out the number of lines in the file. once you are through the file,... Read More

Both of them are used to declare local variables. The variables declared with ’my’ can live only within the block and cannot gets its visibility inherited fucntions called within that block, but one defined as ’local’ canlive... Read More

You can use the XML::DOM navigation methods to navigate thorugh an XML::DOM node tree and use the getnodevalue to recover the data. DOM Parser is used when it is neede to do node operation. Instead we may use SAX parser if you require simple... Read More

it is a default variable which holds automatically, a list of arguements passed to the subroutine within parentheses. Read More

We use the DBI(Database Independent Interface) module to connect to any database. use DBI; $dh = DBI->connect("dbi:mysql:database=DBname","username","password"); $sth = $dh-> prepare("select name, symbol from table"); $sth->execute(); while(... Read More

-w option enables warning - strict pragma is used when you should declare variables before their use -T is taint mode. TAint mode makes a program more secure by keeping track of arguments which are passed from external source. Read More

perldoc command with -f option is the best. i also go to search.cpan.org for help Read More

it provides a GUI interface Read More

A hash is like an associative array, in that it is a collection of scalar data, with individual elements selected by some index value which essentially are scallars and called as keys. Each key corresponds to some value. Hashes are represented by %... Read More

special file handler to standard error in any package Read More

it defines a pattern for a search to match Read More

functionally, there is no difference between them. Read More

exec runs the given process, switches to its name and never returns while system forks off the given process, waits for its to complete and then return Read More

CPAN is comprehensive Perl Archive Network. its a repository contains thousands of Perl Modules, source and documentation, and all under GNU/GPL or smilar licence. you can go to www.cpan.org for more details. Some linux distribution provide a till... Read More

in Win32::ODBC, DataHash() function is used to get the data fetched thorugh the sql statement in a hash format. Read More

make up Read More

&myvariable is calling a sub-routine. & is used to indentify a subroutine Read More

use Win32::OLE Read More

Perl can have objects whose data cannot be accessed outside its class, but C++ cannot. Perl can use closures with unreachable private data as objects, and C++ doesn’t support closures. Furthermore, C++ does support pointer arithmetic via `int ... Read More

Data files are opened in Perl using the open() function. When you open a data file, all you have to do is specify (a) a file handle and (b) the name of the file you want to read from. As an example, suppose you need to read some data from a file... Read More

#!/usr/bin/perl -w opendir(DIR, "."); @files = readdir(DIR); closedir(DIR); foreach $file (@files) { print "$file "; } Read More

here is a snippet of code that just prints a listing of every file in teh current directory. that ends with the entension #!/usr/bin/perl -w opendir(DIR, "."); @files = grep(/.html$/,readdir(DIR)); closedir(DIR); foreach $file (@files) { print "$file... Read More

. Perl has a flexible concept of data types. Scalar meAns a single thing, like a number or string. So the Java concept of int, float, double and string equals to Perl’s scalar in concept and the numbers and strings are exchangeable. Scalar... Read More

You can’t do that. If it weren’t for HTML comments, improperly formatted HTML, and tags with interesting data like < SCRIPT >, you could do this. Alas, you cannot. It takes a lot more smarts, and quite frankly, a real parser Read More

Q.    I  want users send data by formmail but when they send nothing or call it from web site they will see error. codes in PHP like this: if (isset($HTTP_POST_VARS)){ .......... } else{ echo ("error lalalalal") } How it will look... Read More

prog1.cpp Read More

Because Perl patterns have backreferences. A regular expression by definition must be able to determine the next state in the finite automaton without requiring any extra memory to keep around previous state. A pattern /([ab]+)c1/ requires the state... Read More

Here’s a simple technique to process each element in a hash: #!/usr/bin/perl -w %days = ( ’Sun’ =>’Sunday’, ’Mon’ => ’Monday’, ’Tue’ => ’Tuesday’, ’Wed&rsquo... Read More

. print scalar reverse scalar Surprisingly enough, you have to put both the reverse and the into scalar context separately for this to work. Read More

Sending e-mail from a Perl/CGI program on a Unix computer system is usually pretty simple. Most Perl programs directly invoke the Unix sendmail program. We’ll go through a quick example here.Assuming that you’ve already have e-mail... Read More

False so long as f() returns false, after which it returns true until g() returns true, and then starts the cycle again. This is scalar not list context, so we have the bistable flip-flop range operator famous in parsing of mail messages, as in `... Read More

. Because you can inspect the argument count, return context, and object types all by yourself. In Perl, the number of arguments is trivially available to a function via the scalar sense of @_, the return context via wantarray(), and the types of the... Read More

$@array Read More

The undefined value in scalar context, and the empty list value () in list context. This way functions that wish to return failure can just use a simple return without worrying about the context in which they were called. Read More

The second would match Foo other than at the start of the record if $* were set. The deprecated $* flag does double duty, filling the roles of both /s and /m. By using /s, you suppress any settings of that spooky variable, and force your carets and... Read More

Yes. Perl can make a scalar or hash type reference by using backslash operator. For example $str = "here we go"; # a scalar variable $strref = $str; # a reference to a scalar @array = (1..10); # an array $arrayref = @array; # a reference to an array... Read More

5 length() is a built-in prototyped as sub length($), and a scalar prototype silently changes aggregates into radically different forms. The scalar sense of a hash is false (0) if it’s empty, otherwise it’s a string representing the... Read More

The second is disallowed under `use strict "refs"’. Dereferencing a string with *{"STR"} is disallowed under the refs stricture, although *{STR} would not be. This is similar in spirit to the way ${"STR"} is always the symbol table variable,... Read More

#!/usr/bin/perl -w @homeRunHitters = (’McGwire’, ’Sosa’, ’Maris’, ’Ruth’); foreach (@homeRunHitters) { print "$_ hit a lot of home runs in one year "; } Read More

Once you have the libwww-perl library, LWP.pm installed, the code is this: #!/usr/bin/perl use LWP::Simple; $url = get ’http://www.websitename.com/’; Read More

through . operator Read More

With Perl, command-line arguments are stored in the array named @ARGV. $ARGV[0] contains the first argument, $ARGV[1] contains the second argument, etc. $#ARGV is the subscript of the last element of the @ARGV array, so the number of arguments on the... Read More

What happens to objects lost in "unreachable" memory, such as the object returned by Ob->new() in `{ my $ap; $ap = [ Ob->new(), $ap ]; }’ ? Their destructors are called when that interpreter thread shuts down. When the interpreter exits,... Read More

$$ref; # returns a scalar $$ref[0]; # returns the first element of that array $ref- > [0]; # returns the first element of that array @$ref; # returns the contents of that array, or number of elements, in scalar context $&$ref; # returns the... Read More

To Answer this question, we first need a sample array. Let’s assume that you have an array that contains the name of baseball teams, like this: @teams = (’cubs’, ’reds’, ’yankees’, ’dodgers’); If... Read More

They are not identical. There are several differences between using single quotes and double quotes for strings. 1. The double-quoted string will perform variable interpolation on its contents. That is, any variable references inside the quotes will... Read More

Create a scope surrounding that sub that contains lexicals. Only lexical variables are truly private, and they will persist even when their block exits if something still cares about them. Thus: { my $i = 0; sub next_i { $i++ } sub last_i { --$i } }... Read More

because Perl’s basic data structure is all flat, references are the only way to build complex structures, which meAns references can be used in very tricky ways. This question is easy, though. In $array[3], "array" is the (symbolic) name of an... Read More

There is one simple and elegant solution for removing duplicates from a list in PERL @array = (2,4,3,3,4,6,2); my %seen = (); my @unique = grep { ! $seen{ $_ }++ } @array; print "@unique"; Read More

perl is a programming language based off of C, shell, Lisp and a few other things. It is mostly used for OS program, network operations and some website development (mostly cgi). Read More

#!/usr/bin/perl -w   use strict; my($test,$number) = ("",""); $test = "12344tyyyyy456"; $number = ($test =~ tr/[0-9]/[0-9]/); print "Number of digits in variable is :- $number "; exit; Read More

When would you use Perl for a project?   1. When you are developing an application for a real time system in which processing speed is of utmost importance   When to use Perl 1. For large text... Read More

$str=’Hello’; $cnt= ($str=~s/l/i/g); print $cnt; Read More

open FILEHANDLE, ">$FILENAME" Read More

Technically, there’s no difference between for and foreach other than some style issues.   One is an alias of another. You can do things like this foreach (my $i = 0; $i < 3; ++$i) { # normally this is... Read More

My Favourite module is CGI.pm Bcoz it can handle almost all the tasks like 1. parsing the form input 2. printiing the headers 3. can handle cookies and sessions and much more Read More

The variables declared with "my" can live only within the block it was defined and there is no visibility to inherited functions which were called within that block, but one defined with "local" they can live within the block... Read More

system calls *traditionally* returns 0 when successful and 1 when it fails. system ( cmd ) && die "Error - could run cmdn"; Read More

perl -p -i.bak -e ’s/search_str/replace_str/g’  filename... Read More

bless $objref,’XYZ’; Read More

 "eval" and "if ($@)" is the equivalent of a try/catch in the C programming world. My question is how to basically throw an error in one perl script that can be caught by another Consider the following example: ... Read More

You can able check the array contains a particular value is exist or not? For example see the below code. @array = (1,2,3,4,5,6,7,8,100,200,500); # array $result = grep(/600/, @array); # checking the value. print... Read More

Perl is easy, fast and its fun to code in perl. Perl is rich with various packages, N/w programming is very easy and there are lot more advantages to say. Read More

You can use SAX if what you require is simple accesing of the xml structure. You can go for DOM if you need node handling capabilities like inserting a node, modifying a node, deleteing node and stuff like that. Read More

rmtree($dir) ;   Read More

The various command line arguments are -e executes the prog given as an argument-d start perl debugger on the file name specified as an argument-c compile the file given as an argumentThanks -T for taint mode for security... Read More

It is a default variable which hold automatically the list of arguments passed to subroutines within parentheses. Read More

It is an array that contains all the data that is passed to a function. Read More

actually it is used in automation testing....as a tester i am using per script for automation testing like running the tools etc. Read More

In perl we have DBI module to connect to any database. step1: we need to intialise the DBI module use DBI; step2 : connect to database using DBI module which reutrns database handle $dh = DBI->connect("dbi... Read More

die: outputs stderr then exit and also it can trap errors by evalexit: just exits or exit with EXPR Read More

perldoc -f print Read More

the quoting opeator for lists is qw.advantage of qw is you need not quote the strings in additional way as qw already does quoting. Read More

Whatever you want to write in shell script is possible in perl..the only diff is its easy to maintain and write perl scripts then shell.. lots of module etc are available for perl... u not need to rit everything frm scratch...also since... Read More

STDERRThe special filehandle for standard error in any package. Read More

CPAN ic Comprehencive Perl Archive Network. Its a repository contains thousands of Perl modules, source and documentation, and all under GNU/GPL or similar licence. you can go to www.cpan.org for more details. Some Linux distributions... Read More

In Win32::ODBC, DataHash() function is used to get the data fetched through the sql statement in a hash format. Read More

DBI Read More

In reality PERL interpreter is written in C. So what all advantages C have are also possesed by PERL.  Otherwise C is faster than PERL, because PERL is an interpreted language. Read More

 A subroutine is like a function ... called upon to excecute a task. Read More

Super refers to current package ancestor. Read More

The following names have special meaning to perl. I could have used alphabetic symbols for some of these, but I didn’t want to take the chance that someone would say reset "a-zA-Z" and wipe them all out. You’ll just have to... Read More

RPC:A call to a procedure in a different address space. In a traditional procedure call, the calling procedure and the called procedure are in the same address space on one machine. In a remote procedure call, the calling procedure... Read More

ndd command will hardcore the speed of the network interface card. Read More

OBP is called as Open Boot PROM. This OBP can be accessiable thru ok> prompt (Fourth monitor) Read More

You can get system diagonostics information thru prtdiag command. And you can execute this command by /usr/platform/’uname -m’/sbin/prtdiag -v|more Read More

Booting form CD-ROM can be done by the command ok >boot cdrom Read More

/etc/system is a kernal file of Solaris OS. Read More

fmthard will create partitions in a new disk as in a already created/designed disk. For example we can get output from prtvtoc command and give as a input to the new disk as follows. prtvtoc /dev/rmt/c0t0d0s0 > a | fmthard ... Read More

The Jumpstart feature is an automatic installation process available in the Solaris operating environment. It allows system administrators to categorize machines on their network and automatically install systems based on the category... Read More

 pkgmk -o -r / -d /tmp -f Prototype Read More

             Inner Join              Outer Join - Right Outer Join        ... Read More

allows you to tune, tweak, set and reset various parameters related to the TCP/IP stack while the system is running Read More

           create table xyz as ( select * from abc where 1=0) Read More

Answers 1.”where” is used to filter records returned by “Select” 2.”where” appears before group by clause 3.In “where” we cannot use aggrigate functions like where count(*)>2 etc 4.”having” appears... Read More

A database link is an object in the local database that allows you to access objects on a remote database or to mount a secondary database in read-only mode. CREATE [PUBLIC] DATABASE LINK dblink [CONNECT TO user IDENTIFIED BY... Read More

you can just do something like this: $path = $ENV{’PATH’}; As you may remember, "%ENV" is a special hash in Perl that contains the value of all your environment variables. Because %ENV is a hash, you can... Read More

Perl can have objects whose data cannot be accessed outside its class, but C++ cannot. Perl can use closures with unreachable private data as objects, and C++ doesn’t support closures. Furthermore, C++ does support pointer... Read More

Data files are opened in Perl using the open() function. When you open a data file, all you have to do is specify (a) a file handle and (b) the name of the file you want to read from. As an example, suppose you need to read some... Read More

Here’s code that just prints a listing of every file in the current directory: #!/usr/bin/perl -w opendir(DIR, "."); @files = readdir(DIR); closedir(DIR); foreach $file (@files) { print "$file... Read More

Here’s a snippet of code that just prints a listing of every file in the current directory that ends with the extension .html: #!/usr/bin/perl -w opendir(DIR, "."); @files = grep(/.html$/,readdir(DIR)); ... Read More

${var} is the lexical variable $var, and ${"var"} is the dynamic variable $var. Note that because the second is a symbol table lookup, it is disallowed under `use strict "refs"’. The words global, local, package, symbol table,... Read More

Perl keeps track of your variables, whether dynamic or otherwise, and doesn’t free things before you’re done using them. Read More

Perl is very forgiving of strange and sometimes wrong code, which can mean hours spent searching for bugs and weird results. Turning on warnings helps uncover common mistakes and strange places and save a lot of debugging time in... Read More

Many Perl developers use the -w option of the interpreter, especially during the development stages of an application. This warning option turns on many warning messages that can help you understand and debug your applications. To... Read More

Perl has a flexible concept of data types. Scalar means a single thing, like a number or string. So the Java concept of int, float, double and string equals to Perl’s scalar in concept and the numbers and strings are... Read More

Q: Assuming $_ contains HTML, which of the following substitutions will remove all tags in it?      1.s/<.*>//g;      2.s/<.*?>//gs;      3.s/... Read More

Q: What is the output of the following Perl program? 1 $p1 = "prog1.java"; 2 $p1 =~ s/(.*).java/$1.cpp/; 3 print "$p1 "; A: prog1.cpp Read More

Because Perl patterns have backreferences. A regular expression by definition must be able to determine the next state in the finite automaton without requiring any extra memory to keep around previous state. A pattern /([ab]+)c1/ requires the... Read More

Suppose we have a class of five students. Their names are kim, al, rocky, chrisy, and jane. Here’s a test program that prints the contents of the grades hash, sorted by student name: #!/usr/bin... Read More

print scalar reverse scalar <FH> Surprisingly enough, you have to put both the reverse and the <FH> into scalar context separately for this to work. Read More

Because y is a kind of quoting operator. The y/// operator is the sed-savvy synonym for tr///. That means y(3) would be like tr(), which would be looking for a second string, as in tr/a-z/A-Z/, tr(a-z)(A-Z), or tr[a-z][A-Z]. Read More

False so long as f() returns false, after which it returns true until g() returns true, and then starts the cycle again. This is scalar not list context, so we have the bistable flip-flop range operator famous in parsing of... Read More

Because you can inspect the argument count, return context, and object types all by yourself. In Perl, the number of arguments is trivially available to a function via the scalar sense of @_, the return context via wantarray()... Read More

A defined (but false) 0 value is the proper indication of the end of file for read() and sysread(). Read More

Here’s a program that prints the contents of the grades hash, sorted numerically by the hash value: #!/usr/bin/perl -w # Help sort a hash by the hash ’value’, not the ’key’. ... Read More

open(IN, "<name_file") or die "Couldn’t open file for processing: $!"; while (<IN>) { chomp; $hash_table{$_} = 0; } close IN; print "$_ = $hash_table{$_} " foreach keys %hash_table; Read More

 $@array Read More

Yes. Perl can make a scalar or hash type reference by using backslash operator. For example $str = "here we go"; # a scalar variable $strref = $str; # a reference to a scalar @array = (1..10); # an array ... Read More

There are a number of ways to dereference a reference. Using two dollar signs to dereference a scalar. $original = $$strref; Using @ sign to dereference an array. @list = @$arrayref; Similar for hashes. Read More

The second is disallowed under `use strict "refs"’. Dereferencing a string with *{"STR"} is disallowed under the refs stricture, although *{STR} would not be. This is similar in spirit to the way ${"STR"} is always the... Read More

#!/usr/bin/perl -w @homeRunHitters = (’McGwire’, ’Sosa’, ’Maris’, ’Ruth’); foreach (@homeRunHitters) { print "$_ hit a lot of home runs in one year "; } Read More

Method #1 - using Perl’s dot operator: $name = ’checkbook’; $filename = "/tmp/" . $name . ".tmp"; Method #2 - using Perl’s join function $name = "checkbook"; $filename = join "", "/tmp/", $name,... Read More

With Perl, command-line arguments are stored in the array named @ARGV. $ARGV[0] contains the first argument, $ARGV[1] contains the second argument, etc. $#ARGV is the subscript of the last element of the @ARGV array, so... Read More

Their destructors are called when that interpreter thread shuts down. When the interpreter exits, it first does an exhaustive search looking for anything that it allocated. This allows Perl to be used in embedded and multithreaded... Read More

$$ref; # returns a scalar $$ref[0]; # returns the first element of that array $ref- > [0]; # returns the first element of that array @$ref; # returns the contents of that array, or number of elements, in scalar context... Read More

/[^W_d]/ We don’t have full POSIX regexps, so you can’t get at the isalpha() <ctype.h> macro save indirectly. You ask for one byte which is neither a non-alphanumunder, nor an under, nor a numeric. That... Read More

To answer this question, we first need a sample array. Let’s assume that you have an array that contains the name of baseball teams, like this: @teams = (’cubs’, ’reds’, ’yankees’, ... Read More

They are not identical. There are several differences between using single quotes and double quotes for strings. 1. The double-quoted string will perform variable interpolation on its contents. That is, any variable references... Read More

Scalar variables are what many programming languages refer to as simple variables. They hold a single data item, a number, a string, or a perl reference. Scalars are called scalars to differentiate them from constructs that can hold... Read More

A list is a construct that associates data elements together and you can specify a list by enclosing those elements in parenthesis and separating them with commas. They could themselves be arrays, hashes or even other lists. Lists do not... Read More

An ivalue is an item that can serve as the target of an assignment. The term I value originally meant a “left value”, which is to say a value that appears on the left. An ivalue usually represents a data space in memory and you can... Read More

Grep returns the number of lines the expression is true. Grep returns a sublist of a list for which a specific criterion is true. This function often involves pattern matching. It modifies the elements in the original list. Read More

You can change the number of elements in an array simply by changing the value of the last index of/in the array $#array. In fact, if you simply refer to a non existent element in an array perl extends the array as needed, creating new... Read More

The three different ways to empty an array are as follows 1) You can empty an array by setting its length to a negative number. 2) Another way of empting an array is to assign the null list (). 3) Try to clear an array by setting... Read More

An array slice is a section of an array that acts like a list, and you indicate what elements to put into the slice by using multiple array indexes in square brackets. By specifying the range operator you can also specify a slice. Read More

Splicing an array means adding elements from a list to that array, possibly replacing elements now in the array. In list context, the splice function returns the elements removed from the array. In scalar context, the splice function... Read More

There are four different types of perl operators they are (i) Unary operator like the not operator (ii) Binary operator like the addition operator (iii) Tertiary operator like the conditional operator (iv) List operator like the... Read More

The three forms of goto are as follows. They are (i) Goto label (ii) Goto name (iii) Goto expr The first form, goto LABEL, transfers execution to the statement labeled LABEL. The second form, goto EXPR, expects EXPR to evaluate... Read More

There are two different types of eval statements they are eval EXPR and eval BLOCK. Eval EXPR executes an expression and eval BLOCK executes BLOCK. Eval Block executes an entire block, BLOCK. First one is used when you want your code... Read More

The fundamental difference between my and local is that my creates a new variable, whereas local saves a copy of an existing variable. Read More

The return value of the subroutine is the value of the last expression evaluated or you can explicitly use a return statement to exit the subroutine specifying the return value. That return value is evaluated in the appropriate content... Read More

Note that notions of shoe size vary from country to country. See the perllocale man page for complete discussion. -e only returns a boolean value that says whether or not the directory wears a wide shoe. Read More

Have you considered using a mouthwash Read More

Just apply De Morgan’s identity:     A intersection B = complement ((complement A) union (complement B)) Read More

Look into the Net::* modules, available from CPAN. Read More

Because the name of the Deity must always be capitalized. Read More

Try using a whip. Read More

If you got `some weird error’ the problem is with your frobobnitz. Read More

Set it to a true value to create a directory with ice cream on top. Read More

Use this function:         sub creation_date {           use FileHandle;           my $filename = shift or die... Read More

Use this atoi function:         sub atoi {           my $t;           foreach my $d (split(//, shift())) { ... Read More

Use sprintf:                 $string = sprintf("%f", 123.45); Read More

The simplest method is:         if ($string == "$string") {           # It is a number         } Note the use of... Read More

Write a foreach loop to scan the elements one at a time, and stop when you get to the largest one. Read More

        %sorted = sort %hash; Read More

As usual in Perl, there’s More Than One Way to Do it. Use either of:       %sorted = sort values %hash;       %sorted = sort {$hash{$a} <=> $hash{$b}} %hash; The first one... Read More

        @sorted = sort reverse @array; Read More

Even better! New with version 5.005, Perl is Year-2013 compliant. This represents a 13-year improvement over other software that is merely year-2000 compliant. Read More

        s{.*}{Thu Oct  8 09:23:53 1998} Read More

You use /ee when you need to operate on a directory with an extra-wide shoe. Read More

Use this function:         sub tomorrow_date {           sleep 86_400;           return localtime(); ... Read More

fork() only works on Unix systems, so you should use split() for maximum portability. Read More

Sorry, but as you must surely be aware by now, the only animals supported by Perl are ruminants such as camels and llamas. However, Yacc support may be forthcoming with version 5.007. Read More

Only when they are actual quotations. For example, in         $quote = "To be, or not to be?  That is the question."; the quotes are required, but in        ... Read More

Because Perl isn’t C. Duh. Read More

        sub odd {             my $number = shift;             return !even ($number);  ... Read More

        sub even {             my $number = abs shift;             return 1 if $number == 0;... Read More

        $number->lasso(); Read More

                 sub decrypt {           my $c = shift;           my @c = (0) x 8;  ... Read More

In Perl, there’s always more than one way to do it. Try one of these techniques.         use more ’cpu’;         use less ’time’;  ... Read More

Variables take up memory, so if you don’t declare any variables, you should be safe. Another possibility is to use         pack(chop(chomp($0))); Read More

        perldoc perldoc Read More

Make sure that the first line of your script is #!/bin/sh. That magic comment tells the Perl interpreter to understand Bourne shell syntax. Read More

Use: 1. the method is used only for modules (only to include .pm type file) 2. the included object are verified at the time of compilation. 3. No Need to give file extentsion. Require: 1. The method is used for both libraries (... Read More

it is a symbolic link to link one file name to a new name. so lets say we do it like file1-> file2, if we read file1, we end up reading file2. Read More

Q: #create directory if not there if (! -s "$temp/engl_2/wf"){ System "mkdir -p $temp/engl_2/wf"; } if (! -s "$temp/backup_basedir"){ system "mkdir -p $temp/backup_basedir"; } ${pack_2} = -M "${temp}/engl_2/wf/${wf_package_name}... Read More

perl -p -ibak -e ’s/search_str/replace_str/g’ filename Read More

use XYZ my $objref =XYZ -> new() OR, bless $objref, ’XYZ’ Read More

Both of them are used to declare local variables. The variables declared with ’my’ can live only within the block and cannot gets its visibility inherited fucntions called within that block, but one defined as &rsquo... Read More

You can use the XML::DOM navigation methods to navigate thorugh an XML::DOM node tree and use the getnodevalue to recover the data. DOM Parser is used when it is neede to do node operation. Instead we may use SAX parser if you... Read More

There are two ways a Perl script can be run: a)from a command line, called one-liner, that means you type and execute immediately on the command line. You’ll need the -e option to start like "C: %gt perl -e ... Read More

${var} is the lexical variable $var, and ${"var"} is the dynamic variable $var. Note that because the second is a symbol table lookup, it is disallowed under `use strict "refs"’. The words global, local, package,... Read More

The symbol that starts all scalar variables is called a prefix dereferencer. The different types of dereferencer are. (i) $-Scalar variables (ii) %-Hash variables (iii) @-arrays (iv) &... Read More

An ivalue is an item that can serve as the target of an assignment. The term I value originally meant a “left value”, which is to say a value that appears on the left. An ivalue usually represents a data space in memory and you... Read More

An array slice is a section of an array that acts like a list, and you indicate what elements to put into the slice by using multiple array indexes in square brackets. By specifying the range operator you can also specify a slice. Read More

There are four different types of perl operators they are (i) Unary operator like the not operator (ii) Binary operator like the addition operator (iii) Tertiary operator like the conditional operator ... Read More

Terms have the highest precedence in perl. Terms include variables, quotes, expressions in parenthesis etc. List operators have the same level of precedence as terms. Specifically, these operators have very strong left word precedence... Read More

The C-Style operator, ll, performs a logical (or) operation and you can use it to tie logical clauses together, returning an overall value of true if either clause is true. This operator is called a short-circuit operator because if... Read More

The three forms of goto are as follows. They are (i) Goto label (ii) Goto name (iii) Goto expr The first form, goto LABEL, transfers execution to the statement labeled LABEL. The second form, goto... Read More

Of course you can add two arrays together by using push function. The push function adds a value or values to the end of an array. The push function pushes the values of list onto the end of the array. Length of an array can be... Read More

Of course you can add two arrays together by using push function. The push function adds a value or values to the end of an array. The push function pushes the values of list onto the end of the array. Length of an array can be... Read More

Shift array function shifts off the first value of the array and returns it, thereby shortening the array by one element and moving everything from one place to the left. If you don’t specify an array to shift, shift uses @ ARGV... Read More

There are two different types of eval statements they are eval EXPR and eval BLOCK. Eval EXPR executes an expression and eval BLOCK executes BLOCK. Eval Block executes an entire block, BLOCK. First one is used when you want your code... Read More

The fundamental difference between my and local is that my creates a new variable, whereas local saves a copy of an existing variable. Read More

The return value of the subroutine is the value of the last expression evaluated or you can explicitly use a return statement to exit the subroutine specifying the return value. That return value is evaluated in the appropriate... Read More

you can just do something like this: $path = $ENV{’PATH’}; As you may remember, "%ENV" is a special hash in Perl that contains the value of all your environment variables. ... Read More

Perl can have objects whose data cannot be accessed outside its class, but C++ cannot. Perl can use closures with unreachable private data as objects, and C++ doesn’t support closures. Furthermore, C++ does support... Read More

Perl handles two types of data they are (i) Scalar Variables and (ii) Lists Scalar variables hold a single data item whereas lists hold multiple data items. Read More

Many. For example ’this is a string’ can be expressed in: "this is a string" qq/this is a string like double-quoted string/ qq^this is a string like double-quoted string^ q/this is a... Read More

Scalar variables are what many programming languages refer to as simple variables. They hold a single data item, a number, a string, or a perl reference. Scalars are called scalars to differentiate them from constructs that can hold... Read More

Data files are opened in Perl using the open() function. When you open a data file, all you have to do is specify (a) a file handle and (b) the name of the file you want to read from. As an example, suppose you need to read some... Read More

Here’s code that just prints a listing of every file in the current directory: #!/usr/bin/perl -w opendir(DIR, "."); @files = readdir(DIR); closedir(DIR); foreach $file (@files) ... Read More

print scalar reverse scalar Surprisingly enough, you have to put both the reverse and the into scalar context separately for this to work. Read More

Here’s a snippet of code that just prints a listing of every file in the current directory that ends with the extension .html: #!/usr/bin/perl -w opendir(DIR, "."); @files = grep(/.html$/,readdir... Read More

Grep returns the number of lines the expression is true. Grep returns a sublist of a list for which a specific criterion is true. This function often involves pattern matching. It modifies the elements in the original list. Read More

Type globs are another integral type in perl. A typeglob`s prefix derefrencer is *, which is also the wild card character because you can use typeglobs to create an alias for all types associated with a particular name. All kinds of... Read More

Yes. Perl can make a scalar or hash type reference by using backslash operator. For example $str = "here we go"; # a scalar variable $strref = $str; # a reference to a scalar @array = (1..10); #... Read More

There are a number of ways to dereference a reference. Using two dollar signs to dereference a scalar. $original = $$strref; Using @ sign to dereference an array. @list = @$arrayref; ... Read More

Perl is very forgiving of strange and sometimes wrong code, which can mean hours spent searching for bugs and weird results. Turning on warnings helps uncover common mistakes and strange places and save a lot of debugging time in the... Read More

there is a ’ref’ function that lets you know Read More

. rmtree($dir); OR, you can use CPAN module File::Remove Though it sounds like deleting file but it can be used also for deleting directories. &File::Removes::remove (1,$feed-dir,$item_dir); Read More

e for Execute, -c to compile, -d to call the debugger on the file specified, -T for traint mode for security/input checking -W for show all warning mode (or -w to show less warning) Read More

whatever you can do in shell script can be done in Perl.however 1. Perl gives you an extended advantages of having enormous library. 2. you do not need to write everything from scartch Read More

it tries to match the longest string possible. Read More

. you can just do something like this: $ENV{’PATH’} = ’...’; As you may remember, "%ENV" is a special hash in Perl that contains the value of all your environment variables. Because %ENV is a hash, you can set environment... Read More

There are two ways a Perl script can be run: --from a command line, called one-liner, that meAns you type and execute immediately on the command line. You’ll need the -e option to start like "C: %gt perl -e "print "Hello";". One-liner doesn... Read More

Perl keeps track of your variables, whether dynamic or otherwise, and doesn’t free things before you’re done using them Read More

Sends mail to root and exits. It has been said that all programs advance to the point of being able to automatically read mail. While not quite at that point (well, without having a module loaded), Perl does at least automatically send it. Read More

Suppose we have a class of five students.Their names are kim, al, rocky, chrisy, and jane. Here’s a test program that prints the contents of the grades hash, sorted by student name: #!/usr/bin/perl -w %grades = ( kim => 96, al => 63,... Read More

$cur->new()->{LINK} The indirect object syntax only has a single token lookahead. That meAns if new() is a method, it only grabs the very next token, not the entire following expression. This is why `new $obj[23] arg’ does’t work,... Read More

Here’s a program that prints the contents of the grades hash, sorted numerically by the hash value: #!/usr/bin/perl -w # Help sort a hash by the hash ’value’, not the ’key’. to highest). sub hashValueAscendingNum { ... Read More

perl -pi.bak -e ’s/ /,/g’ myfile. Read More

/[^W_d]/ We don’t have full POSIX regexps, so you can’t get at the isalpha() macro save indirectly. You ask for one byte which is neither a non-alphanumunder, nor an under, nor a numeric. That leaves just the alphas, which is what you... Read More

Many. For example ’this is a string’ can be expressed in: "this is a string" qq/this is a string like double-quoted string/ qq^this is a string like double-quoted string^ q/this is a string/ q&this is a string& q(this is a string)... Read More

chop is used remove last character,chomp function removes only line endings. Read More

Hash is an associative array where data is stored in "key"->"value" pairs.   Eg : fruits is a hash having their names and price%fruits = ("Apple", "60", "Banana", "20", "Peers", "40") Read More

we will get a no.of  modules from CPAN , there so many module for database interface, database drivers. to do the mathematical operations ,text processing . each module is to handle a small tasks .   There are... Read More

-w enables the  warnings mode in perl   -T is enables the  Taint mode it performs some checks how your program is using the data passed to it Turn on strict mode to make Perl check for common mistakes. ... Read More

reference the method of a module. Read More

Pack Converts a list into a binary representation Takes an array or list of values and packs it into a binary structure, returning the string containing the structure Takes a LIST of values and converts it into a... Read More

Stack is LIFO (Last in First out), In perl that could be inplemented using the push() and shift() functions. push() adds the element at the last of array and shift() removes from the beginning of an array. Read More

Holds the name of the default heading format for the default file handle. Normally, it is equal to the file handle’s name with _TOP appended to it. Read More

Perl regular expressions normally match the longest string possible. that is what is called as "greedy match" Read More

init 5 will shutdown and Power-off the server. init 0 will bring the server to the ok> prompt (Fourth monitor) Read More

boot net - install Read More

boot cdrom Read More

The fmthard command updates the VTOC (Volume Table of Contents) on hard disks and, on systems, adds boot information,to the Solaris fdisk partition. One or more of the options,-s datafile, -d data, or -n volume_name must be used to... Read More

Sun Validation Test Suite -> tests and validates Sun hardware by verifying the configuration and functionality of hardware controllers, devices Read More

Drop Table - will remove the existance of the table from the database along with its data and structure and all the constraints. The table will be no longer available. Truncate Table - will remove all the rows (only the rows) from... Read More

There are two ways a Perl script can be run: --from a command line, called one-liner, that means you type and execute immediately on the command line. You’ll need the -e option to start like "C: %gt perl -e "print "Hello... Read More

Sends mail to root and exits. It has been said that all programs advance to the point of being able to automatically read mail. While not quite at that point (well, without having a module loaded), Perl does at least... Read More

Sending e-mail from a Perl/CGI program on a Unix computer system is usually pretty simple. Most Perl programs directly invoke the Unix sendmail program. We’ll go through a quick example here. Assuming that you’ve... Read More

Example 1: To run the date command from a Perl program, and read the output of the command, all you need are a few lines of code like this: open(DATE, "date|"); $theDate = <DATE>; close(DATE); The open(... Read More

$cur->new()->{LINK} The indirect object syntax only has a single token lookahead. That means if new() is a method, it only grabs the very next token, not the entire following expression. This is why `new $obj[23] arg... Read More

The undefined value in scalar context, and the empty list value () in list context. This way functions that wish to return failure can just use a simple return without worrying about the context in which they were called. Read More

The second would match Foo other than at the start of the record if $* were set. The deprecated $* flag does double duty, filling the roles of both /s and /m. By using /s, you suppress any settings of that spooky variable, and... Read More

When your caller was in the middle for a while(m//g) loop The /g state on a global variable is not protected by running local on it. That’ll teach you to stop using locals. Too bad $_ can’t be the target of a my()... Read More

/[^W_d]/ We don’t have full POSIX regexps, so you can’t get at the isalpha() <ctype.h> macro save indirectly. You ask for one byte which is neither a non-alphanumunder, nor an under, nor a numeric.... Read More

Create a scope surrounding that sub that contains lexicals. Only lexical variables are truly private, and they will persist even when their block exits if something still cares about them. Thus: { my $i = 0; sub next_i { ... Read More

Perl handles two types of data they are (i) Scalar Variables and (ii) Lists Scalar variables hold a single data item whereas lists hold multiple data items. Read More

Of course you can add two arrays together by using push function. The push function adds a value or values to the end of an array. The push function pushes the values of list onto the end of the array. Length of an array can be increased... Read More

Shift array function shifts off the first value of the array and returns it, thereby shortening the array by one element and moving everything from one place to the left. If you don’t specify an array to shift, shift uses @ ARGV,... Read More

The C-Style operator, ll, performs a logical (or) operation and you can use it to tie logical clauses together, returning an overall value of true if either clause is true. This operator is called a short-circuit operator because if the... Read More

Use         $string x .5; Read More

tr/// is faster on multiprocessor machines because it can be vectorized, so that each x is removed by a different processor. s///, however, must always be performed sequentially. Read More

Use         length(’$variable’); to find out how long a variable is. Read More

Just as C programmers use .cpp as an extension for their object oriented C programs, many perl programmers use .ppp for their object oriented Perl programs. Read More

Use the sleep function, like this:   use POSIX ":sys_wait_h";   { local($SIG{CHLD}=sub{wait};     my $start = time;     if (fork) { sleep } else { 1 while (time - $start < 5); exit }   } Read More

Watch your $@*$!% mouth, buddy! Read More

The simplest way is to do         close STDERR; Read More

If you’re using gcc, version 2.7 or better, you can use the translate-to-perl mode.         gcc -P -E foo.c > foo.pl (gcc is smart enough to figure out that you want to convert to &rsquo... Read More

Single quoted strings act like q(); double quoted strings act like qq().   Read More

Ans: there is a ’ref’ function that lets you know Read More

’chop’ functiononly removes the last character completely ’from the scaler, where as ’chomp’ function only removes the last character if it is a newline. by default, chomp only removes what is currently... Read More

> @solution = sort {lc $a comp lc$b } @arr. Read More

System calls "traditionally" returns 9 when successful and 1 when it fails. system (cmd) or die "Error in command"; Read More

through push() and shift() function. push adds the element at the last of array and shift() removes from the beginning of an array. Read More

Splicing an array means adding elements from a list to that array, possibly replacing elements now in the array. In list context, the splice function returns the elements removed from the array. In scalar context, the splice function... Read More

A list is a construct that associates data elements together and you can specify a list by enclosing those elements in parenthesis and separating them with commas. They could themselves be arrays, hashes or even other lists. Lists do... Read More

Perl has a flexible concept of data types. Scalar means a single thing, like a number or string. So the Java concept of int, float, double and string equals to Perl’s scalar in concept and the numbers and strings are... Read More