1*0Sstevel@tonic-gate=head1 NAME 2*0Sstevel@tonic-gate 3*0Sstevel@tonic-gateperlfaq1 - General Questions About Perl ($Revision: 1.14 $, $Date: 2003/11/23 08:02:29 $) 4*0Sstevel@tonic-gate 5*0Sstevel@tonic-gate=head1 DESCRIPTION 6*0Sstevel@tonic-gate 7*0Sstevel@tonic-gateThis section of the FAQ answers very general, high-level questions 8*0Sstevel@tonic-gateabout Perl. 9*0Sstevel@tonic-gate 10*0Sstevel@tonic-gate=head2 What is Perl? 11*0Sstevel@tonic-gate 12*0Sstevel@tonic-gatePerl is a high-level programming language with an eclectic heritage 13*0Sstevel@tonic-gatewritten by Larry Wall and a cast of thousands. It derives from the 14*0Sstevel@tonic-gateubiquitous C programming language and to a lesser extent from sed, 15*0Sstevel@tonic-gateawk, the Unix shell, and at least a dozen other tools and languages. 16*0Sstevel@tonic-gatePerl's process, file, and text manipulation facilities make it 17*0Sstevel@tonic-gateparticularly well-suited for tasks involving quick prototyping, system 18*0Sstevel@tonic-gateutilities, software tools, system management tasks, database access, 19*0Sstevel@tonic-gategraphical programming, networking, and world wide web programming. 20*0Sstevel@tonic-gateThese strengths make it especially popular with system administrators 21*0Sstevel@tonic-gateand CGI script authors, but mathematicians, geneticists, journalists, 22*0Sstevel@tonic-gateand even managers also use Perl. Maybe you should, too. 23*0Sstevel@tonic-gate 24*0Sstevel@tonic-gate=head2 Who supports Perl? Who develops it? Why is it free? 25*0Sstevel@tonic-gate 26*0Sstevel@tonic-gateThe original culture of the pre-populist Internet and the deeply-held 27*0Sstevel@tonic-gatebeliefs of Perl's author, Larry Wall, gave rise to the free and open 28*0Sstevel@tonic-gatedistribution policy of perl. Perl is supported by its users. The 29*0Sstevel@tonic-gatecore, the standard Perl library, the optional modules, and the 30*0Sstevel@tonic-gatedocumentation you're reading now were all written by volunteers. See 31*0Sstevel@tonic-gatethe personal note at the end of the README file in the perl source 32*0Sstevel@tonic-gatedistribution for more details. See L<perlhist> (new as of 5.005) 33*0Sstevel@tonic-gatefor Perl's milestone releases. 34*0Sstevel@tonic-gate 35*0Sstevel@tonic-gateIn particular, the core development team (known as the Perl Porters) 36*0Sstevel@tonic-gateare a rag-tag band of highly altruistic individuals committed to 37*0Sstevel@tonic-gateproducing better software for free than you could hope to purchase for 38*0Sstevel@tonic-gatemoney. You may snoop on pending developments via the archives at 39*0Sstevel@tonic-gatehttp://www.xray.mpe.mpg.de/mailing-lists/perl5-porters/ 40*0Sstevel@tonic-gateand http://archive.develooper.com/perl5-porters@perl.org/ 41*0Sstevel@tonic-gateor the news gateway nntp://nntp.perl.org/perl.perl5.porters or 42*0Sstevel@tonic-gateits web interface at http://nntp.perl.org/group/perl.perl5.porters , 43*0Sstevel@tonic-gateor read the faq at http://simon-cozens.org/writings/p5p-faq , 44*0Sstevel@tonic-gateor you can subscribe to the mailing list by sending 45*0Sstevel@tonic-gateperl5-porters-request@perl.org a subscription request 46*0Sstevel@tonic-gate(an empty message with no subject is fine). 47*0Sstevel@tonic-gate 48*0Sstevel@tonic-gateWhile the GNU project includes Perl in its distributions, there's no 49*0Sstevel@tonic-gatesuch thing as "GNU Perl". Perl is not produced nor maintained by the 50*0Sstevel@tonic-gateFree Software Foundation. Perl's licensing terms are also more open 51*0Sstevel@tonic-gatethan GNU software's tend to be. 52*0Sstevel@tonic-gate 53*0Sstevel@tonic-gateYou can get commercial support of Perl if you wish, although for most 54*0Sstevel@tonic-gateusers the informal support will more than suffice. See the answer to 55*0Sstevel@tonic-gate"Where can I buy a commercial version of perl?" for more information. 56*0Sstevel@tonic-gate 57*0Sstevel@tonic-gate=head2 Which version of Perl should I use? 58*0Sstevel@tonic-gate 59*0Sstevel@tonic-gateYou should definitely use version 5. Version 4 is old, limited, and 60*0Sstevel@tonic-gateno longer maintained; its last patch (4.036) was in 1992, long ago and 61*0Sstevel@tonic-gatefar away. Sure, it's stable, but so is anything that's dead; in fact, 62*0Sstevel@tonic-gateperl4 had been called a dead, flea-bitten camel carcass. The most 63*0Sstevel@tonic-gaterecent production release is 5.8.2 (although 5.005_03 and 5.6.2 are 64*0Sstevel@tonic-gatestill supported). The most cutting-edge development release is 5.9. 65*0Sstevel@tonic-gateFurther references to the Perl language in this document refer to the 66*0Sstevel@tonic-gateproduction release unless otherwise specified. There may be one or 67*0Sstevel@tonic-gatemore official bug fixes by the time you read this, and also perhaps 68*0Sstevel@tonic-gatesome experimental versions on the way to the next release. 69*0Sstevel@tonic-gateAll releases prior to 5.004 were subject to buffer overruns, a grave 70*0Sstevel@tonic-gatesecurity issue. 71*0Sstevel@tonic-gate 72*0Sstevel@tonic-gate=head2 What are perl4 and perl5? 73*0Sstevel@tonic-gate 74*0Sstevel@tonic-gatePerl4 and perl5 are informal names for different versions of the Perl 75*0Sstevel@tonic-gateprogramming language. It's easier to say "perl5" than it is to say 76*0Sstevel@tonic-gate"the 5(.004) release of Perl", but some people have interpreted this 77*0Sstevel@tonic-gateto mean there's a language called "perl5", which isn't the case. 78*0Sstevel@tonic-gatePerl5 is merely the popular name for the fifth major release (October 1994), 79*0Sstevel@tonic-gatewhile perl4 was the fourth major release (March 1991). There was also a 80*0Sstevel@tonic-gateperl1 (in January 1988), a perl2 (June 1988), and a perl3 (October 1989). 81*0Sstevel@tonic-gate 82*0Sstevel@tonic-gateThe 5.0 release is, essentially, a ground-up rewrite of the original 83*0Sstevel@tonic-gateperl source code from releases 1 through 4. It has been modularized, 84*0Sstevel@tonic-gateobject-oriented, tweaked, trimmed, and optimized until it almost doesn't 85*0Sstevel@tonic-gatelook like the old code. However, the interface is mostly the same, and 86*0Sstevel@tonic-gatecompatibility with previous releases is very high. 87*0Sstevel@tonic-gateSee L<perltrap/"Perl4 to Perl5 Traps">. 88*0Sstevel@tonic-gate 89*0Sstevel@tonic-gateTo avoid the "what language is perl5?" confusion, some people prefer to 90*0Sstevel@tonic-gatesimply use "perl" to refer to the latest version of perl and avoid using 91*0Sstevel@tonic-gate"perl5" altogether. It's not really that big a deal, though. 92*0Sstevel@tonic-gate 93*0Sstevel@tonic-gateSee L<perlhist> for a history of Perl revisions. 94*0Sstevel@tonic-gate 95*0Sstevel@tonic-gate=head2 What is Ponie? 96*0Sstevel@tonic-gate 97*0Sstevel@tonic-gateAt The O'Reilly Open Source Software Convention in 2003, Artur 98*0Sstevel@tonic-gateBergman, Fotango, and The Perl Foundation announced a project to 99*0Sstevel@tonic-gaterun perl5 on the Parrot virtual machine named Ponie. Ponie stands for 100*0Sstevel@tonic-gatePerl On New Internal Engine. The Perl 5.10 language implementation 101*0Sstevel@tonic-gatewill be used for Ponie, and there will be no language level 102*0Sstevel@tonic-gatedifferences between perl5 and ponie. Ponie is not a complete rewrite 103*0Sstevel@tonic-gateof perl5. 104*0Sstevel@tonic-gate 105*0Sstevel@tonic-gateFor more details, see http://www.poniecode.org/ 106*0Sstevel@tonic-gate 107*0Sstevel@tonic-gate=head2 What is perl6? 108*0Sstevel@tonic-gate 109*0Sstevel@tonic-gateAt The Second O'Reilly Open Source Software Convention, Larry Wall 110*0Sstevel@tonic-gateannounced Perl6 development would begin in earnest. Perl6 was an oft 111*0Sstevel@tonic-gateused term for Chip Salzenberg's project to rewrite Perl in C++ named 112*0Sstevel@tonic-gateTopaz. However, Topaz provided valuable insights to the next version 113*0Sstevel@tonic-gateof Perl and its implementation, but was ultimately abandoned. 114*0Sstevel@tonic-gate 115*0Sstevel@tonic-gateIf you want to learn more about Perl6, or have a desire to help in 116*0Sstevel@tonic-gatethe crusade to make Perl a better place then peruse the Perl6 developers 117*0Sstevel@tonic-gatepage at http://dev.perl.org/perl6/ and get involved. 118*0Sstevel@tonic-gate 119*0Sstevel@tonic-gatePerl6 is not scheduled for release yet, and Perl5 will still be supported 120*0Sstevel@tonic-gatefor quite awhile after its release. Do not wait for Perl6 to do whatever 121*0Sstevel@tonic-gateyou need to do. 122*0Sstevel@tonic-gate 123*0Sstevel@tonic-gate"We're really serious about reinventing everything that needs reinventing." 124*0Sstevel@tonic-gate--Larry Wall 125*0Sstevel@tonic-gate 126*0Sstevel@tonic-gate=head2 How stable is Perl? 127*0Sstevel@tonic-gate 128*0Sstevel@tonic-gateProduction releases, which incorporate bug fixes and new functionality, 129*0Sstevel@tonic-gateare widely tested before release. Since the 5.000 release, we have 130*0Sstevel@tonic-gateaveraged only about one production release per year. 131*0Sstevel@tonic-gate 132*0Sstevel@tonic-gateLarry and the Perl development team occasionally make changes to the 133*0Sstevel@tonic-gateinternal core of the language, but all possible efforts are made toward 134*0Sstevel@tonic-gatebackward compatibility. While not quite all perl4 scripts run flawlessly 135*0Sstevel@tonic-gateunder perl5, an update to perl should nearly never invalidate a program 136*0Sstevel@tonic-gatewritten for an earlier version of perl (barring accidental bug fixes 137*0Sstevel@tonic-gateand the rare new keyword). 138*0Sstevel@tonic-gate 139*0Sstevel@tonic-gate=head2 Is Perl difficult to learn? 140*0Sstevel@tonic-gate 141*0Sstevel@tonic-gateNo, Perl is easy to start learning--and easy to keep learning. It looks 142*0Sstevel@tonic-gatelike most programming languages you're likely to have experience 143*0Sstevel@tonic-gatewith, so if you've ever written a C program, an awk script, a shell 144*0Sstevel@tonic-gatescript, or even a BASIC program, you're already partway there. 145*0Sstevel@tonic-gate 146*0Sstevel@tonic-gateMost tasks only require a small subset of the Perl language. One of 147*0Sstevel@tonic-gatethe guiding mottos for Perl development is "there's more than one way 148*0Sstevel@tonic-gateto do it" (TMTOWTDI, sometimes pronounced "tim toady"). Perl's 149*0Sstevel@tonic-gatelearning curve is therefore shallow (easy to learn) and long (there's 150*0Sstevel@tonic-gatea whole lot you can do if you really want). 151*0Sstevel@tonic-gate 152*0Sstevel@tonic-gateFinally, because Perl is frequently (but not always, and certainly not by 153*0Sstevel@tonic-gatedefinition) an interpreted language, you can write your programs and test 154*0Sstevel@tonic-gatethem without an intermediate compilation step, allowing you to experiment 155*0Sstevel@tonic-gateand test/debug quickly and easily. This ease of experimentation flattens 156*0Sstevel@tonic-gatethe learning curve even more. 157*0Sstevel@tonic-gate 158*0Sstevel@tonic-gateThings that make Perl easier to learn: Unix experience, almost any kind 159*0Sstevel@tonic-gateof programming experience, an understanding of regular expressions, and 160*0Sstevel@tonic-gatethe ability to understand other people's code. If there's something you 161*0Sstevel@tonic-gateneed to do, then it's probably already been done, and a working example is 162*0Sstevel@tonic-gateusually available for free. Don't forget the new perl modules, either. 163*0Sstevel@tonic-gateThey're discussed in Part 3 of this FAQ, along with CPAN, which is 164*0Sstevel@tonic-gatediscussed in Part 2. 165*0Sstevel@tonic-gate 166*0Sstevel@tonic-gate=head2 How does Perl compare with other languages like Java, Python, REXX, Scheme, or Tcl? 167*0Sstevel@tonic-gate 168*0Sstevel@tonic-gateFavorably in some areas, unfavorably in others. Precisely which areas 169*0Sstevel@tonic-gateare good and bad is often a personal choice, so asking this question 170*0Sstevel@tonic-gateon Usenet runs a strong risk of starting an unproductive Holy War. 171*0Sstevel@tonic-gate 172*0Sstevel@tonic-gateProbably the best thing to do is try to write equivalent code to do a 173*0Sstevel@tonic-gateset of tasks. These languages have their own newsgroups in which you 174*0Sstevel@tonic-gatecan learn about (but hopefully not argue about) them. 175*0Sstevel@tonic-gate 176*0Sstevel@tonic-gateSome comparison documents can be found at http://language.perl.com/versus/ 177*0Sstevel@tonic-gateif you really can't stop yourself. 178*0Sstevel@tonic-gate 179*0Sstevel@tonic-gate=head2 Can I do [task] in Perl? 180*0Sstevel@tonic-gate 181*0Sstevel@tonic-gatePerl is flexible and extensible enough for you to use on virtually any 182*0Sstevel@tonic-gatetask, from one-line file-processing tasks to large, elaborate systems. 183*0Sstevel@tonic-gateFor many people, Perl serves as a great replacement for shell scripting. 184*0Sstevel@tonic-gateFor others, it serves as a convenient, high-level replacement for most of 185*0Sstevel@tonic-gatewhat they'd program in low-level languages like C or C++. It's ultimately 186*0Sstevel@tonic-gateup to you (and possibly your management) which tasks you'll use Perl 187*0Sstevel@tonic-gatefor and which you won't. 188*0Sstevel@tonic-gate 189*0Sstevel@tonic-gateIf you have a library that provides an API, you can make any component 190*0Sstevel@tonic-gateof it available as just another Perl function or variable using a Perl 191*0Sstevel@tonic-gateextension written in C or C++ and dynamically linked into your main 192*0Sstevel@tonic-gateperl interpreter. You can also go the other direction, and write your 193*0Sstevel@tonic-gatemain program in C or C++, and then link in some Perl code on the fly, 194*0Sstevel@tonic-gateto create a powerful application. See L<perlembed>. 195*0Sstevel@tonic-gate 196*0Sstevel@tonic-gateThat said, there will always be small, focused, special-purpose 197*0Sstevel@tonic-gatelanguages dedicated to a specific problem domain that are simply more 198*0Sstevel@tonic-gateconvenient for certain kinds of problems. Perl tries to be all things 199*0Sstevel@tonic-gateto all people, but nothing special to anyone. Examples of specialized 200*0Sstevel@tonic-gatelanguages that come to mind include prolog and matlab. 201*0Sstevel@tonic-gate 202*0Sstevel@tonic-gate=head2 When shouldn't I program in Perl? 203*0Sstevel@tonic-gate 204*0Sstevel@tonic-gateWhen your manager forbids it--but do consider replacing them :-). 205*0Sstevel@tonic-gate 206*0Sstevel@tonic-gateActually, one good reason is when you already have an existing 207*0Sstevel@tonic-gateapplication written in another language that's all done (and done 208*0Sstevel@tonic-gatewell), or you have an application language specifically designed for a 209*0Sstevel@tonic-gatecertain task (e.g. prolog, make). 210*0Sstevel@tonic-gate 211*0Sstevel@tonic-gateFor various reasons, Perl is probably not well-suited for real-time 212*0Sstevel@tonic-gateembedded systems, low-level operating systems development work like 213*0Sstevel@tonic-gatedevice drivers or context-switching code, complex multi-threaded 214*0Sstevel@tonic-gateshared-memory applications, or extremely large applications. You'll 215*0Sstevel@tonic-gatenotice that perl is not itself written in Perl. 216*0Sstevel@tonic-gate 217*0Sstevel@tonic-gateThe new, native-code compiler for Perl may eventually reduce the 218*0Sstevel@tonic-gatelimitations given in the previous statement to some degree, but understand 219*0Sstevel@tonic-gatethat Perl remains fundamentally a dynamically typed language, not 220*0Sstevel@tonic-gatea statically typed one. You certainly won't be chastised if you don't 221*0Sstevel@tonic-gatetrust nuclear-plant or brain-surgery monitoring code to it. And Larry 222*0Sstevel@tonic-gatewill sleep easier, too--Wall Street programs not withstanding. :-) 223*0Sstevel@tonic-gate 224*0Sstevel@tonic-gate=head2 What's the difference between "perl" and "Perl"? 225*0Sstevel@tonic-gate 226*0Sstevel@tonic-gateOne bit. Oh, you weren't talking ASCII? :-) Larry now uses "Perl" to 227*0Sstevel@tonic-gatesignify the language proper and "perl" the implementation of it, 228*0Sstevel@tonic-gatei.e. the current interpreter. Hence Tom's quip that "Nothing but perl 229*0Sstevel@tonic-gatecan parse Perl." You may or may not choose to follow this usage. For 230*0Sstevel@tonic-gateexample, parallelism means "awk and perl" and "Python and Perl" look 231*0Sstevel@tonic-gateOK, while "awk and Perl" and "Python and perl" do not. But never 232*0Sstevel@tonic-gatewrite "PERL", because perl is not an acronym, apocryphal 233*0Sstevel@tonic-gatefolklore and post-facto expansions notwithstanding. 234*0Sstevel@tonic-gate 235*0Sstevel@tonic-gate=head2 Is it a Perl program or a Perl script? 236*0Sstevel@tonic-gate 237*0Sstevel@tonic-gateLarry doesn't really care. He says (half in jest) that "a script is 238*0Sstevel@tonic-gatewhat you give the actors. A program is what you give the audience." 239*0Sstevel@tonic-gate 240*0Sstevel@tonic-gateOriginally, a script was a canned sequence of normally interactive 241*0Sstevel@tonic-gatecommands--that is, a chat script. Something like a UUCP or PPP chat 242*0Sstevel@tonic-gatescript or an expect script fits the bill nicely, as do configuration 243*0Sstevel@tonic-gatescripts run by a program at its start up, such F<.cshrc> or F<.ircrc>, 244*0Sstevel@tonic-gatefor example. Chat scripts were just drivers for existing programs, 245*0Sstevel@tonic-gatenot stand-alone programs in their own right. 246*0Sstevel@tonic-gate 247*0Sstevel@tonic-gateA computer scientist will correctly explain that all programs are 248*0Sstevel@tonic-gateinterpreted and that the only question is at what level. But if you 249*0Sstevel@tonic-gateask this question of someone who isn't a computer scientist, they might 250*0Sstevel@tonic-gatetell you that a I<program> has been compiled to physical machine code 251*0Sstevel@tonic-gateonce and can then be run multiple times, whereas a I<script> must be 252*0Sstevel@tonic-gatetranslated by a program each time it's used. 253*0Sstevel@tonic-gate 254*0Sstevel@tonic-gatePerl programs are (usually) neither strictly compiled nor strictly 255*0Sstevel@tonic-gateinterpreted. They can be compiled to a byte-code form (something of a 256*0Sstevel@tonic-gatePerl virtual machine) or to completely different languages, like C or 257*0Sstevel@tonic-gateassembly language. You can't tell just by looking at it whether the 258*0Sstevel@tonic-gatesource is destined for a pure interpreter, a parse-tree interpreter, 259*0Sstevel@tonic-gatea byte-code interpreter, or a native-code compiler, so it's hard to give 260*0Sstevel@tonic-gatea definitive answer here. 261*0Sstevel@tonic-gate 262*0Sstevel@tonic-gateNow that "script" and "scripting" are terms that have been seized by 263*0Sstevel@tonic-gateunscrupulous or unknowing marketeers for their own nefarious purposes, 264*0Sstevel@tonic-gatethey have begun to take on strange and often pejorative meanings, 265*0Sstevel@tonic-gatelike "non serious" or "not real programming". Consequently, some Perl 266*0Sstevel@tonic-gateprogrammers prefer to avoid them altogether. 267*0Sstevel@tonic-gate 268*0Sstevel@tonic-gate=head2 What is a JAPH? 269*0Sstevel@tonic-gate 270*0Sstevel@tonic-gateThese are the "just another perl hacker" signatures that some people 271*0Sstevel@tonic-gatesign their postings with. Randal Schwartz made these famous. About 272*0Sstevel@tonic-gate100 of the earlier ones are available from 273*0Sstevel@tonic-gatehttp://www.cpan.org/misc/japh . 274*0Sstevel@tonic-gate 275*0Sstevel@tonic-gate=head2 Where can I get a list of Larry Wall witticisms? 276*0Sstevel@tonic-gate 277*0Sstevel@tonic-gateOver a hundred quips by Larry, from postings of his or source code, 278*0Sstevel@tonic-gatecan be found at http://www.cpan.org/misc/lwall-quotes.txt.gz . 279*0Sstevel@tonic-gate 280*0Sstevel@tonic-gate=head2 How can I convince my sysadmin/supervisor/employees to use version 5/5.6.1/Perl instead of some other language? 281*0Sstevel@tonic-gate 282*0Sstevel@tonic-gateIf your manager or employees are wary of unsupported software, or 283*0Sstevel@tonic-gatesoftware which doesn't officially ship with your operating system, you 284*0Sstevel@tonic-gatemight try to appeal to their self-interest. If programmers can be 285*0Sstevel@tonic-gatemore productive using and utilizing Perl constructs, functionality, 286*0Sstevel@tonic-gatesimplicity, and power, then the typical manager/supervisor/employee 287*0Sstevel@tonic-gatemay be persuaded. Regarding using Perl in general, it's also 288*0Sstevel@tonic-gatesometimes helpful to point out that delivery times may be reduced 289*0Sstevel@tonic-gateusing Perl compared to other languages. 290*0Sstevel@tonic-gate 291*0Sstevel@tonic-gateIf you have a project which has a bottleneck, especially in terms of 292*0Sstevel@tonic-gatetranslation or testing, Perl almost certainly will provide a viable, 293*0Sstevel@tonic-gatequick solution. In conjunction with any persuasion effort, you 294*0Sstevel@tonic-gateshould not fail to point out that Perl is used, quite extensively, and 295*0Sstevel@tonic-gatewith extremely reliable and valuable results, at many large computer 296*0Sstevel@tonic-gatesoftware and hardware companies throughout the world. In fact, 297*0Sstevel@tonic-gatemany Unix vendors now ship Perl by default. Support is usually 298*0Sstevel@tonic-gatejust a news-posting away, if you can't find the answer in the 299*0Sstevel@tonic-gateI<comprehensive> documentation, including this FAQ. 300*0Sstevel@tonic-gate 301*0Sstevel@tonic-gateSee http://www.perl.org/advocacy/ for more information. 302*0Sstevel@tonic-gate 303*0Sstevel@tonic-gateIf you face reluctance to upgrading from an older version of perl, 304*0Sstevel@tonic-gatethen point out that version 4 is utterly unmaintained and unsupported 305*0Sstevel@tonic-gateby the Perl Development Team. Another big sell for Perl5 is the large 306*0Sstevel@tonic-gatenumber of modules and extensions which greatly reduce development time 307*0Sstevel@tonic-gatefor any given task. Also mention that the difference between version 308*0Sstevel@tonic-gate4 and version 5 of Perl is like the difference between awk and C++. 309*0Sstevel@tonic-gate(Well, OK, maybe it's not quite that distinct, but you get the idea.) 310*0Sstevel@tonic-gateIf you want support and a reasonable guarantee that what you're 311*0Sstevel@tonic-gatedeveloping will continue to work in the future, then you have to run 312*0Sstevel@tonic-gatethe supported version. As of December 2003 that means running either 313*0Sstevel@tonic-gate5.8.2 (released in November 2003), or one of the older releases like 314*0Sstevel@tonic-gate5.6.2 (also released in November 2003; a maintenance release to let perl 315*0Sstevel@tonic-gate5.6 compile on newer systems as 5.6.1 was released in April 2001) or 316*0Sstevel@tonic-gate5.005_03 (released in March 1999), 317*0Sstevel@tonic-gatealthough 5.004_05 isn't that bad if you B<absolutely> need such an old 318*0Sstevel@tonic-gateversion (released in April 1999) for stability reasons. 319*0Sstevel@tonic-gateAnything older than 5.004_05 shouldn't be used. 320*0Sstevel@tonic-gate 321*0Sstevel@tonic-gateOf particular note is the massive bug hunt for buffer overflow 322*0Sstevel@tonic-gateproblems that went into the 5.004 release. All releases prior to 323*0Sstevel@tonic-gatethat, including perl4, are considered insecure and should be upgraded 324*0Sstevel@tonic-gateas soon as possible. 325*0Sstevel@tonic-gate 326*0Sstevel@tonic-gateIn August 2000 in all Linux distributions a new security problem was 327*0Sstevel@tonic-gatefound in the optional 'suidperl' (not built or installed by default) 328*0Sstevel@tonic-gatein all the Perl branches 5.6, 5.005, and 5.004, see 329*0Sstevel@tonic-gatehttp://www.cpan.org/src/5.0/sperl-2000-08-05/ 330*0Sstevel@tonic-gatePerl maintenance releases 5.6.1 and 5.8.0 have this security hole closed. 331*0Sstevel@tonic-gateMost, if not all, Linux distribution have patches for this 332*0Sstevel@tonic-gatevulnerability available, see http://www.linuxsecurity.com/advisories/ , 333*0Sstevel@tonic-gatebut the most recommendable way is to upgrade to at least Perl 5.6.1. 334*0Sstevel@tonic-gate 335*0Sstevel@tonic-gate=head1 AUTHOR AND COPYRIGHT 336*0Sstevel@tonic-gate 337*0Sstevel@tonic-gateCopyright (c) 1997, 1998, 1999, 2000, 2001 Tom Christiansen and Nathan 338*0Sstevel@tonic-gateTorkington. All rights reserved. 339*0Sstevel@tonic-gate 340*0Sstevel@tonic-gateThis documentation is free; you can redistribute it and/or modify it 341*0Sstevel@tonic-gateunder the same terms as Perl itself. 342*0Sstevel@tonic-gate 343*0Sstevel@tonic-gateIrrespective of its distribution, all code examples here are in the public 344*0Sstevel@tonic-gatedomain. You are permitted and encouraged to use this code and any 345*0Sstevel@tonic-gatederivatives thereof in your own programs for fun or for profit as you 346*0Sstevel@tonic-gatesee fit. A simple comment in the code giving credit to the FAQ would 347*0Sstevel@tonic-gatebe courteous but is not required. 348