Perl Tutorials

1. Steps to Install perl-Apache-DBI in linux

By: Emiley J : 2012-09-07

Description: If you get this error while installing perl-Apache-DBI, Loaded plugins: fastestmirror, priorities, security, update-motd Loading mirror speeds from cached hostfile * amzn-main: packages.us-east-1.amazonaws.com * amzn-updates: packages.us-east-1.amazonaws.com Setting up Install Process No package perl-Apache-DBI available. Error: Nothing to do, then you follow these steps to resolve it.


2. Extract filename from full path using perl

By: Sam Chen : 2012-07-13

Description: This is a simple trick but comes in handy when you need to extract just the filename from the full path.


3. Flush history file on disk (unique hosts reach flush limit of 20000) - Awstats

By: Emiley J : 2011-10-01

Description: When you run awstats.pl on your server on a log file that is quite big, you will see this Flush history file on disk (unique hosts reach flush limit of 20000) message on the window. Be assured that this is not an error. This is just a message for you to inform that more than 20000 hosts were found on the log file and flushed and the program is still running to process the rest of the log file.


4. What is Perl?

By: Boopathy : 2011-02-05

Description: Perl is a high-level, general-purpose, interpreted, dynamic programming language. Perl was originally developed by Larry Wall in 1987 as a general-purpose Unix scripting language to make report processing easier. Since then, it has undergone many changes and revisions and become widely popular amongst programmers. Larry Wall continues to oversee development of the core language, and its upcoming version, Perl 6. Perl borrows features from other programming languages including C, shell scripting (sh), AWK, and sed. The language provides powerful text processing facilities without the arbitrary data length limits of many contemporary Unix tools, facilitating easy manipulation of text files. Perl gained widespread popularity in the late 1990s as a CGI scripting language, in part due to its parsing abilities.


5. History of Perl?

By: Boopathy : 2011-02-05

Description: Larry Wall began work on Perl in 1987, while working as a programmer at Unisys, and released version 1.0 to the comp.sources.misc newsgroup on December 18, 1987. The language expanded rapidly over the next few years.


6. Why was it named Perl?

By: Boopathy : 2011-02-05

Description: Perl was originally named "Pearl", after the Parable of the Pearl from the Gospel of Matthew. Larry Wall wanted to give the language a short name with positive connotations; he claims that he considered (and rejected) every three- and four-letter word in the dictionary. He also considered naming it after his wife Gloria. Wall discovered the existing PEARL programming language before Perl's official release and changed the spelling of the name.


7. Major features of Perl

By: Boopathy : 2011-02-05

Description: All versions of Perl do automatic data-typing and automatic memory-management. The interpreter knows the type and storage requirements of every data object in the program; it allocates and frees storage for them as necessary using reference counting (so it cannot deallocate circular data structures without manual intervention). Legal type-conversions — for example, conversions from number to string — are done automatically at run time; illegal type conversions are fatal errors.


8. The design of Perl

By: Boopathy : 2011-02-05

Description: The design of Perl can be understood as a response to three broad trends in the computer industry: falling hardware costs, rising labor costs, and improvements in compiler technology. Many earlier computer languages, such as Fortran and C, aimed to make efficient use of expensive computer hardware. In contrast, Perl is designed to make efficient use of expensive computer-programmers.


9. Perl Applications

By: Boopathy : 2011-02-05

Description: Ever since the early days of the Web, programmers have used Perl to write CGI scripts. Perl is known as one of "the three Ps" (along with Python and PHP), the most popular dynamic languages for writing Web applications. It is also an integral component of the popular LAMP solution stack for web development. Large projects written in Perl include cPanel, Slash, Bugzilla, RT, TWiki, and Movable Type. Many high-traffic websites use Perl extensively. Examples include Amazon.com, bbc.co.uk, Priceline.com, Craigslist, IMDb, LiveJournal, Slashdot and Ticketmaster.


10. Implementation of Perl

By: Boopathy : 2011-02-05

Description: Perl is implemented as a core interpreter, written in C, together with a large collection of modules, written in Perl and C. as of 2010, the stable version (5.12.3) is 14.2 MB when packaged in a tar file and gzip compressed. The interpreter is 150,000 lines of C code and compiles to a 1 MB executable on typical machine architectures. Alternatively, the interpreter can be compiled to a link library and embedded in other programs. There are nearly 500 modules in the distribution, comprising 200,000 lines of Perl and an additional 350,000 lines of C code. (Much of the C code in the modules consists of character-encoding tables.)