1perlfaq1(3)           User Contributed Perl Documentation          perlfaq1(3)
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NAME

6       perlfaq1 - General Questions About Perl
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VERSION

9       version 5.20191102
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DESCRIPTION

12       This section of the FAQ answers very general, high-level questions
13       about Perl.
14
15   What is Perl?
16       Perl is a high-level programming language with an eclectic heritage
17       written by Larry Wall and a cast of thousands.
18
19       Perl's process, file, and text manipulation facilities make it
20       particularly well-suited for tasks involving quick prototyping, system
21       utilities, software tools, system management tasks, database access,
22       graphical programming, networking, and web programming.
23
24       Perl derives from the ubiquitous C programming language and to a lesser
25       extent from sed, awk, the Unix shell, and many other tools and
26       languages.
27
28       These strengths make it especially popular with web developers and
29       system administrators. Mathematicians, geneticists, journalists,
30       managers and many other people also use Perl.
31
32   Who supports Perl? Who develops it? Why is it free?
33       The original culture of the pre-populist Internet and the deeply-held
34       beliefs of Perl's author, Larry Wall, gave rise to the free and open
35       distribution policy of Perl. Perl is supported by its users. The core,
36       the standard Perl library, the optional modules, and the documentation
37       you're reading now were all written by volunteers.
38
39       The core development team (known as the Perl Porters) are a group of
40       highly altruistic individuals committed to producing better software
41       for free than you could hope to purchase for money. You may snoop on
42       pending developments via the archives
43       <http://www.nntp.perl.org/group/perl.perl5.porters/> or you can
44       subscribe to the mailing list by sending
45       perl5-porters-subscribe@perl.org a subscription request (an empty
46       message with no subject is fine).
47
48       While the GNU project includes Perl in its distributions, there's no
49       such thing as "GNU Perl". Perl is not produced nor maintained by the
50       Free Software Foundation. Perl's licensing terms are also more open
51       than GNU software's tend to be.
52
53       You can get commercial support of Perl if you wish, although for most
54       users the informal support will more than suffice. See the answer to
55       "Where can I buy a commercial version of Perl?" for more information.
56
57   Which version of Perl should I use?
58       (contributed by brian d foy with updates from others)
59
60       There is often a matter of opinion and taste, and there isn't any one
61       answer that fits everyone. In general, you want to use either the
62       current stable release, or the stable release immediately prior to that
63       one.
64
65       Beyond that, you have to consider several things and decide which is
66       best for you.
67
68       ·   If things aren't broken, upgrading perl may break them (or at least
69           issue new warnings).
70
71       ·   The latest versions of perl have more bug fixes.
72
73       ·   The latest versions of perl may contain performance improvements
74           and features not present in older versions.  There have been many
75           changes in perl since perl5 was first introduced.
76
77       ·   The Perl community is geared toward supporting the most recent
78           releases, so you'll have an easier time finding help for those.
79
80       ·   Older versions of perl may have security vulnerabilities, some of
81           which are serious (see perlsec and search CVEs
82           <https://cve.mitre.org/cgi-bin/cvekey.cgi?keyword=Perl> for more
83           information).
84
85       ·   The latest versions are probably the least deployed and widely
86           tested, so you may want to wait a few months after their release
87           and see what problems others have if you are risk averse.
88
89       ·   The immediate, in addition to the current stable release, the
90           previous stable release is maintained.  See "MAINTENANCE AND
91           SUPPORT" in perlpolicy for more information.
92
93       ·   There are really two tracks of perl development: a maintenance
94           version and an experimental version. The maintenance versions are
95           stable, and have an even number as the minor release (i.e.
96           perl5.24.x, where 24 is the minor release). The experimental
97           versions may include features that don't make it into the stable
98           versions, and have an odd number as the minor release (i.e.
99           perl5.25.x, where 25 is the minor release).
100
101       ·   You can consult releases <http://dev.perl.org/perl5> to determine
102           the current stable release of Perl.
103
104   What are Perl 4, Perl 5, or Perl 6?
105       In short, Perl 4 is the parent to both Perl 5 and Perl 6. Perl 5 is the
106       older sibling, and though they are different languages, someone who
107       knows one will spot many similarities in the other.
108
109       The number after Perl (i.e. the 5 after Perl 5) is the major release of
110       the perl interpreter as well as the version of the language. Each major
111       version has significant differences that earlier versions cannot
112       support.
113
114       The current major release of Perl is Perl 5, first released in 1994. It
115       can run scripts from the previous major release, Perl 4 (March 1991),
116       but has significant differences.
117
118       Perl 6 is a reinvention of Perl, it is a language in the same lineage
119       but not compatible. The two are complementary, not mutually exclusive.
120       Perl 6 is not meant to replace Perl 5, and vice versa. See "What is
121       Perl 6?" below to find out more.
122
123       See perlhist for a history of Perl revisions.
124
125   What is Perl 6?
126       Perl 6 was originally described as the community's rewrite of Perl 5,
127       however as the language evolved, it became clear that it is a separate
128       language, but in the same language family as Perl 5.
129
130       Perl 6 is not intended primarily as a replacement for Perl 5, but as
131       its own thing - and libraries exist to allow you to call Perl 5 code
132       from Perl 6 programs and vice versa.
133
134       Contrary to popular belief, Perl 6 and Perl 5 peacefully coexist with
135       one another. Perl 6 has proven to be a fascinating source of ideas for
136       those using Perl 5 (the Moose object system is a well-known example).
137       There is overlap in the communities, and this overlap fosters the
138       tradition of sharing and borrowing that have been instrumental to
139       Perl's success.
140
141       If you want to learn more about Perl 6 read the Perl 6 developers page
142       at <http://www.perl6.org/> and get involved.
143
144       "We're really serious about reinventing everything that needs
145       reinventing."  --Larry Wall
146
147   How stable is Perl?
148       Production releases, which incorporate bug fixes and new functionality,
149       are widely tested before release. Since the 5.000 release, we have
150       averaged about one production release per year.
151
152       The Perl development team occasionally make changes to the internal
153       core of the language, but all possible efforts are made toward backward
154       compatibility.
155
156   How often are new versions of Perl released?
157       Recently, the plan has been to release a new version of Perl roughly
158       every April, but getting the release right is more important than
159       sticking rigidly to a calendar date, so the release date is somewhat
160       flexible.  The historical release dates can be viewed at
161       <http://www.cpan.org/src/README.html>.
162
163       Even numbered minor versions (5.14, 5.16, 5.18) are production
164       versions, and odd numbered minor versions (5.15, 5.17, 5.19) are
165       development versions. Unless you want to try out an experimental
166       feature, you probably never want to install a development version of
167       Perl.
168
169       The Perl development team are called Perl 5 Porters, and their
170       organization is described at <http://perldoc.perl.org/perlpolicy.html>.
171       The organizational rules really just boil down to one: Larry is always
172       right, even when he was wrong.
173
174   Is Perl difficult to learn?
175       No, Perl is easy to start learning <http://learn.perl.org/> --and easy
176       to keep learning. It looks like most programming languages you're
177       likely to have experience with, so if you've ever written a C program,
178       an awk script, a shell script, or even a BASIC program, you're already
179       partway there.
180
181       Most tasks only require a small subset of the Perl language. One of the
182       guiding mottos for Perl development is "there's more than one way to do
183       it" (TMTOWTDI, sometimes pronounced "tim toady"). Perl's learning curve
184       is therefore shallow (easy to learn) and long (there's a whole lot you
185       can do if you really want).
186
187       Finally, because Perl is frequently (but not always, and certainly not
188       by definition) an interpreted language, you can write your programs and
189       test them without an intermediate compilation step, allowing you to
190       experiment and test/debug quickly and easily. This ease of
191       experimentation flattens the learning curve even more.
192
193       Things that make Perl easier to learn: Unix experience, almost any kind
194       of programming experience, an understanding of regular expressions, and
195       the ability to understand other people's code. If there's something you
196       need to do, then it's probably already been done, and a working example
197       is usually available for free. Don't forget Perl modules, either.
198       They're discussed in Part 3 of this FAQ, along with CPAN
199       <http://www.cpan.org/>, which is discussed in Part 2.
200
201   How does Perl compare with other languages like Java, Python, REXX, Scheme,
202       or Tcl?
203       Perl can be used for almost any coding problem, even ones which require
204       integrating specialist C code for extra speed. As with any tool it can
205       be used well or badly. Perl has many strengths, and a few weaknesses,
206       precisely which areas are good and bad is often a personal choice.
207
208       When choosing a language you should also be influenced by the resources
209       <http://www.cpan.org/>, testing culture <http://www.cpantesters.org/>
210       and community <http://www.perl.org/community.html> which surrounds it.
211
212       For comparisons to a specific language it is often best to create a
213       small project in both languages and compare the results, make sure to
214       use all the resources <http://www.cpan.org/> of each language, as a
215       language is far more than just it's syntax.
216
217   Can I do [task] in Perl?
218       Perl is flexible and extensible enough for you to use on virtually any
219       task, from one-line file-processing tasks to large, elaborate systems.
220
221       For many people, Perl serves as a great replacement for shell
222       scripting.  For others, it serves as a convenient, high-level
223       replacement for most of what they'd program in low-level languages like
224       C or C++. It's ultimately up to you (and possibly your management)
225       which tasks you'll use Perl for and which you won't.
226
227       If you have a library that provides an API, you can make any component
228       of it available as just another Perl function or variable using a Perl
229       extension written in C or C++ and dynamically linked into your main
230       perl interpreter. You can also go the other direction, and write your
231       main program in C or C++, and then link in some Perl code on the fly,
232       to create a powerful application. See perlembed.
233
234       That said, there will always be small, focused, special-purpose
235       languages dedicated to a specific problem domain that are simply more
236       convenient for certain kinds of problems. Perl tries to be all things
237       to all people, but nothing special to anyone. Examples of specialized
238       languages that come to mind include prolog and matlab.
239
240   When shouldn't I program in Perl?
241       One good reason is when you already have an existing application
242       written in another language that's all done (and done well), or you
243       have an application language specifically designed for a certain task
244       (e.g. prolog, make).
245
246       If you find that you need to speed up a specific part of a Perl
247       application (not something you often need) you may want to use C, but
248       you can access this from your Perl code with perlxs.
249
250   What's the difference between "perl" and "Perl"?
251       "Perl" is the name of the language. Only the "P" is capitalized.  The
252       name of the interpreter (the program which runs the Perl script) is
253       "perl" with a lowercase "p".
254
255       You may or may not choose to follow this usage. But never write "PERL",
256       because perl is not an acronym.
257
258   What is a JAPH?
259       (contributed by brian d foy)
260
261       JAPH stands for "Just another Perl hacker,", which Randal Schwartz used
262       to sign email and usenet messages starting in the late 1980s. He
263       previously used the phrase with many subjects ("Just another x
264       hacker,"), so to distinguish his JAPH, he started to write them as Perl
265       programs:
266
267           print "Just another Perl hacker,";
268
269       Other people picked up on this and started to write clever or
270       obfuscated programs to produce the same output, spinning things quickly
271       out of control while still providing hours of amusement for their
272       creators and readers.
273
274       CPAN has several JAPH programs at <http://www.cpan.org/misc/japh>.
275
276   How can I convince others to use Perl?
277       (contributed by brian d foy)
278
279       Appeal to their self interest! If Perl is new (and thus scary) to them,
280       find something that Perl can do to solve one of their problems. That
281       might mean that Perl either saves them something (time, headaches,
282       money) or gives them something (flexibility, power, testability).
283
284       In general, the benefit of a language is closely related to the skill
285       of the people using that language. If you or your team can be faster,
286       better, and stronger through Perl, you'll deliver more value. Remember,
287       people often respond better to what they get out of it. If you run into
288       resistance, figure out what those people get out of the other choice
289       and how Perl might satisfy that requirement.
290
291       You don't have to worry about finding or paying for Perl; it's freely
292       available and several popular operating systems come with Perl.
293       Community support in places such as Perlmonks (
294       <http://www.perlmonks.com> ) and the various Perl mailing lists (
295       <http://lists.perl.org> ) means that you can usually get quick answers
296       to your problems.
297
298       Finally, keep in mind that Perl might not be the right tool for every
299       job. You're a much better advocate if your claims are reasonable and
300       grounded in reality. Dogmatically advocating anything tends to make
301       people discount your message. Be honest about possible disadvantages to
302       your choice of Perl since any choice has trade-offs.
303
304       You might find these links useful:
305
306       ·   <http://www.perl.org/about.html>
307
308       ·   <http://perltraining.com.au/whyperl.html>
309
311       Copyright (c) 1997-2010 Tom Christiansen, Nathan Torkington, and other
312       authors as noted. All rights reserved.
313
314       This documentation is free; you can redistribute it and/or modify it
315       under the same terms as Perl itself.
316
317       Irrespective of its distribution, all code examples here are in the
318       public domain. You are permitted and encouraged to use this code and
319       any derivatives thereof in your own programs for fun or for profit as
320       you see fit. A simple comment in the code giving credit to the FAQ
321       would be courteous but is not required.
322
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325perl v5.30.0                      2019-11-04                       perlfaq1(3)
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