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Text File | 1996-03-02 | 23.0 KB | 397 lines

PERL(1) User Contributed Perl Documentation PERL(1) NNNNAAAAMMMMEEEE perl - Practical Extraction and Report Language SSSSYYYYNNNNOOOOPPPPSSSSIIIISSSS ppppeeeerrrrllll [ ----aaaaccccddddhhhhnnnnppppPPPPssssSSSSTTTTuuuuUUUUvvvvwwww ] [ ----0000[_o_c_t_a_l] ] [ ----DDDD_n_u_m_b_e_r_/_l_i_s_t] ] [ ----FFFF_s_t_r_i_n_g ] [ ----iiii[_e_x_t_e_n_s_i_o_n] ] [ ----IIII_d_i_r ] [ ----llll_o_c_t_a_l ] [ ----xxxx_d_i_r ] [ _p_r_o_g_r_a_m_f_i_l_e | ----eeee _c_o_m_m_a_n_d ] [ _a_r_g_u_m_e_n_t ... ] For ease of access, the Perl manual has been split up into a number of sections: ppppeeeerrrrllll PPPPeeeerrrrllll oooovvvveeeerrrrvvvviiiieeeewwww ((((tttthhhhiiiissss sssseeeeccccttttiiiioooonnnn)))) ppppeeeerrrrllllttttoooocccc PPPPeeeerrrrllll ddddooooccccuuuummmmeeeennnnttttaaaattttiiiioooonnnn ttttaaaabbbblllleeee ooooffff ccccoooonnnntttteeeennnnttttssss ppppeeeerrrrllllddddaaaattttaaaa PPPPeeeerrrrllll ddddaaaattttaaaa ssssttttrrrruuuuccccttttuuuurrrreeeessss ppppeeeerrrrllllssssyyyynnnn PPPPeeeerrrrllll ssssyyyynnnnttttaaaaxxxx ppppeeeerrrrlllloooopppp PPPPeeeerrrrllll ooooppppeeeerrrraaaattttoooorrrrssss aaaannnndddd pppprrrreeeecccceeeeddddeeeennnncccceeee ppppeeeerrrrllllrrrreeee PPPPeeeerrrrllll rrrreeeegggguuuullllaaaarrrr eeeexxxxpppprrrreeeessssssssiiiioooonnnnssss ppppeeeerrrrllllrrrruuuunnnn PPPPeeeerrrrllll eeeexxxxeeeeccccuuuuttttiiiioooonnnn aaaannnndddd ooooppppttttiiiioooonnnnssss ppppeeeerrrrllllffffuuuunnnncccc PPPPeeeerrrrllll bbbbuuuuiiiillllttttiiiinnnn ffffuuuunnnnccccttttiiiioooonnnnssss ppppeeeerrrrllllvvvvaaaarrrr PPPPeeeerrrrllll pppprrrreeeeddddeeeeffffiiiinnnneeeedddd vvvvaaaarrrriiiiaaaabbbblllleeeessss ppppeeeerrrrllllssssuuuubbbb PPPPeeeerrrrllll ssssuuuubbbbrrrroooouuuuttttiiiinnnneeeessss ppppeeeerrrrllllmmmmoooodddd PPPPeeeerrrrllll mmmmoooodddduuuulllleeeessss ppppeeeerrrrllllrrrreeeeffff PPPPeeeerrrrllll rrrreeeeffffeeeerrrreeeennnncccceeeessss ppppeeeerrrrllllddddsssscccc PPPPeeeerrrrllll ddddaaaattttaaaa ssssttttrrrruuuuccccttttuuuurrrreeeessss iiiinnnnttttrrrroooo ppppeeeerrrrlllllllloooollll PPPPeeeerrrrllll ddddaaaattttaaaa ssssttttrrrruuuuccccttttuuuurrrreeeessss:::: lllliiiissssttttssss ooooffff lllliiiissssttttssss ppppeeeerrrrlllloooobbbbjjjj PPPPeeeerrrrllll oooobbbbjjjjeeeeccccttttssss ppppeeeerrrrllllttttiiiieeee PPPPeeeerrrrllll oooobbbbjjjjeeeeccccttttssss hhhhiiiiddddddddeeeennnn bbbbeeeehhhhiiiinnnndddd ssssiiiimmmmpppplllleeee vvvvaaaarrrriiiiaaaabbbblllleeeessss ppppeeeerrrrllllbbbbooootttt PPPPeeeerrrrllll OOOOOOOO ttttrrrriiiicccckkkkssss aaaannnndddd eeeexxxxaaaammmmpppplllleeeessss ppppeeeerrrrllllddddeeeebbbbuuuugggg PPPPeeeerrrrllll ddddeeeebbbbuuuuggggggggiiiinnnngggg ppppeeeerrrrllllddddiiiiaaaagggg PPPPeeeerrrrllll ddddiiiiaaaaggggnnnnoooossssttttiiiicccc mmmmeeeessssssssaaaaggggeeeessss ppppeeeerrrrllllffffoooorrrrmmmm PPPPeeeerrrrllll ffffoooorrrrmmmmaaaattttssss ppppeeeerrrrlllliiiippppcccc PPPPeeeerrrrllll iiiinnnntttteeeerrrrpppprrrroooocccceeeessssssss ccccoooommmmmmmmuuuunnnniiiiccccaaaattttiiiioooonnnn ppppeeeerrrrllllsssseeeecccc PPPPeeeerrrrllll sssseeeeccccuuuurrrriiiittttyyyy ppppeeeerrrrllllttttrrrraaaapppp PPPPeeeerrrrllll ttttrrrraaaappppssss ffffoooorrrr tttthhhheeee uuuunnnnwwwwaaaarrrryyyy ppppeeeerrrrllllssssttttyyyylllleeee PPPPeeeerrrrllll ssssttttyyyylllleeee gggguuuuiiiiddddeeee ppppeeeerrrrllllxxxxssss PPPPeeeerrrrllll XXXXSSSS aaaapppppppplllliiiiccccaaaattttiiiioooonnnn pppprrrrooooggggrrrraaaammmmmmmmiiiinnnngggg iiiinnnntttteeeerrrrffffaaaacccceeee ppppeeeerrrrllllxxxxssssttttuuuutttt PPPPeeeerrrrllll XXXXSSSS ttttuuuuttttoooorrrriiiiaaaallll ppppeeeerrrrllllgggguuuuttttssss PPPPeeeerrrrllll iiiinnnntttteeeerrrrnnnnaaaallll ffffuuuunnnnccccttttiiiioooonnnnssss ffffoooorrrr tttthhhhoooosssseeee ddddooooiiiinnnngggg eeeexxxxtttteeeennnnssssiiiioooonnnnssss ppppeeeerrrrllllccccaaaallllllll PPPPeeeerrrrllll ccccaaaalllllllliiiinnnngggg ccccoooonnnnvvvveeeennnnttttiiiioooonnnnssss ffffrrrroooommmm CCCC ppppeeeerrrrlllleeeemmmmbbbbeeeedddd PPPPeeeerrrrllll hhhhoooowwww ttttoooo eeeemmmmbbbbeeeedddd ppppeeeerrrrllll iiiinnnn yyyyoooouuuurrrr CCCC oooorrrr CCCC++++++++ aaaapppppppp ppppeeeerrrrllllppppoooodddd PPPPeeeerrrrllll ppppllllaaaaiiiinnnn oooolllldddd ddddooooccccuuuummmmeeeennnnttttaaaattttiiiioooonnnn ppppeeeerrrrllllbbbbooooooookkkk PPPPeeeerrrrllll bbbbooooooookkkk iiiinnnnffffoooorrrrmmmmaaaattttiiiioooonnnn (If you're intending to read these straight through for the first time, the suggested order will tend to reduce the number of forward references.) Additional documentation for Perl modules is available in the _/_u_s_r_/_l_o_c_a_l_/_m_a_n_/ directory. Some of this is distributed standard with Perl, but you'll also find third-party modules there. You should be able to view this with your _m_a_n(1) program by including the proper directories in the appropriate start-up files. To find out where these are, type: 30/Jan/96 perl 5.002 with 1 PERL(1) User Contributed Perl Documentation PERL(1) ppppeeeerrrrllll ----lllleeee ''''uuuusssseeee CCCCoooonnnnffffiiiigggg;;;; pppprrrriiiinnnntttt """"@@@@CCCCoooonnnnffffiiiigggg{{{{mmmmaaaannnn1111ddddiiiirrrr,,,,mmmmaaaannnn3333ddddiiiirrrr}}}}""""'''' If the directories were _/_u_s_r_/_l_o_c_a_l_/_m_a_n_/_m_a_n_1 and _/_u_s_r_/_l_o_c_a_l_/_m_a_n_/_m_a_n_3, you would only need to add _/_u_s_r_/_l_o_c_a_l_/_m_a_n to your MANPATH. If they are different, you'll have to add both stems. If that doesn't work for some reason, you can still use the supplied _p_e_r_l_d_o_c script to view module information. You might also look into getting a replacement man program. If something strange has gone wrong with your program and you're not sure where you should look for help, try the ----wwww switch first. It will often point out exactly where the trouble is. DDDDEEEESSSSCCCCRRRRIIIIPPPPTTTTIIIIOOOONNNN Perl is an interpreted language optimized for scanning arbitrary text files, extracting information from those text files, and printing reports based on that information. It's also a good language for many system management tasks. The language is intended to be practical (easy to use, efficient, complete) rather than beautiful (tiny, elegant, minimal). It combines (in the author's opinion, anyway) some of the best features of C, sssseeeedddd, aaaawwwwkkkk, and sssshhhh, so people familiar with those languages should have little difficulty with it. (Language historians will also note some vestiges of ccccsssshhhh, Pascal, and even BASIC-PLUS.) Expression syntax corresponds quite closely to C expression syntax. Unlike most Unix utilities, Perl does not arbitrarily limit the size of your data--if you've got the memory, Perl can slurp in your whole file as a single string. Recursion is of unlimited depth. And the hash tables used by associative arrays grow as necessary to prevent degraded performance. Perl uses sophisticated pattern matching techniques to scan large amounts of data very quickly. Although optimized for scanning text, Perl can also deal with binary data, and can make dbm files look like associative arrays. Setuid Perl scripts are safer than C programs through a dataflow tracing mechanism which prevents many stupid security holes. If you have a problem that would ordinarily use sssseeeedddd or aaaawwwwkkkk or sssshhhh, but it exceeds their capabilities or must run a little faster, and you don't want to write the silly thing in C, then Perl may be for you. There are also translators to turn your sssseeeedddd and aaaawwwwkkkk scripts into Perl scripts. But wait, there's more... Perl version 5 is nearly a complete rewrite, and provides the following additional benefits: 30/Jan/96 perl 5.002 with 2 PERL(1) User Contributed Perl Documentation PERL(1) +o Many usability enhancements It is now possible to write much more readable Perl code (even within regular expressions). Formerly cryptic variable names can be replaced by mnemonic identifiers. Error messages are more informative, and the optional warnings will catch many of the mistakes a novice might make. This cannot be stressed enough. Whenever you get mysterious behavior, try the ----wwww switch!!! Whenever you don't get mysterious behavior, try using ----wwww anyway. +o Simplified grammar The new yacc grammar is one half the size of the old one. Many of the arbitrary grammar rules have been regularized. The number of reserved words has been cut by 2/3. Despite this, nearly all old Perl scripts will continue to work unchanged. +o Lexical scoping Perl variables may now be declared within a lexical scope, like "auto" variables in C. Not only is this more efficient, but it contributes to better privacy for "programming in the large". +o Arbitrarily nested data structures Any scalar value, including any array element, may now contain a reference to any other variable or subroutine. You can easily create anonymous variables and subroutines. Perl manages your reference counts for you. +o Modularity and reusability The Perl library is now defined in terms of modules which can be easily shared among various packages. A package may choose to import all or a portion of a module's published interface. Pragmas (that is, compiler directives) are defined and used by the same mechanism. +o Object-oriented programming A package can function as a class. Dynamic multiple inheritance and virtual methods are supported in a straightforward manner and with very little new syntax. Filehandles may now be treated as objects. +o Embeddable and Extensible Perl may now be embedded easily in your C or C++ application, and can either call or be called by your routines through a documented interface. The XS preprocessor is provided to make it easy to glue your C or C++ routines into Perl. Dynamic loading of modules is supported. 30/Jan/96 perl 5.002 with 3 PERL(1) User Contributed Perl Documentation PERL(1) +o POSIX compliant A major new module is the POSIX module, which provides access to all available POSIX routines and definitions, via object classes where appropriate. +o Package constructors and destructors The new BEGIN and END blocks provide means to capture control as a package is being compiled, and after the program exits. As a degenerate case they work just like awk's BEGIN and END when you use the ----pppp or ----nnnn switches. +o Multiple simultaneous DBM implementations A Perl program may now access DBM, NDBM, SDBM, GDBM, and Berkeley DB files from the same script simultaneously. In fact, the old dbmopen interface has been generalized to allow any variable to be tied to an object class which defines its access methods. +o Subroutine definitions may now be autoloaded In fact, the AUTOLOAD mechanism also allows you to define any arbitrary semantics for undefined subroutine calls. It's not just for autoloading. +o Regular expression enhancements You can now specify non-greedy quantifiers. You can now do grouping without creating a backreference. You can now write regular expressions with embedded whitespace and comments for readability. A consistent extensibility mechanism has been added that is upwardly compatible with all old regular expressions. Ok, that's _d_e_f_i_n_i_t_e_l_y enough hype. EEEENNNNVVVVIIIIRRRROOOONNNNMMMMEEEENNNNTTTT HOME Used if chdir has no argument. LOGDIR Used if chdir has no argument and HOME is not set. PATH Used in executing subprocesses, and in finding the script if ----SSSS is used. PERL5LIB A colon-separated list of directories in which to look for Perl library files before looking in the standard library and the current directory. If PERL5LIB is not defined, PERLLIB is used. When running taint checks (because the script was running setuid or setgid, or the ----TTTT switch was used), neither variable is used. The script should instead say 30/Jan/96 perl 5.002 with 4 PERL(1) User Contributed Perl Documentation PERL(1) uuuusssseeee lllliiiibbbb """"////mmmmyyyy////ddddiiiirrrreeeeccccttttoooorrrryyyy"""";;;; PERL5DB The command used to get the debugger code. If unset, uses BBBBEEEEGGGGIIIINNNN {{{{ rrrreeeeqqqquuuuiiiirrrreeee ''''ppppeeeerrrrllll5555ddddbbbb....ppppllll'''' }}}} PERLLIB A colon-separated list of directories in which to look for Perl library files before looking in the standard library and the current directory. If PERL5LIB is defined, PERLLIB is not used. Apart from these, Perl uses no other environment variables, except to make them available to the script being executed, and to child processes. However, scripts running setuid would do well to execute the following lines before doing anything else, just to keep people honest: $$$$EEEENNNNVVVV{{{{''''PPPPAAAATTTTHHHH''''}}}} ==== ''''////bbbbiiiinnnn::::////uuuussssrrrr////bbbbiiiinnnn'''';;;; #### oooorrrr wwwwhhhhaaaatttteeeevvvveeeerrrr yyyyoooouuuu nnnneeeeeeeedddd $$$$EEEENNNNVVVV{{{{''''SSSSHHHHEEEELLLLLLLL''''}}}} ==== ''''////bbbbiiiinnnn////sssshhhh'''' iiiiffff ddddeeeeffffiiiinnnneeeedddd $$$$EEEENNNNVVVV{{{{''''SSSSHHHHEEEELLLLLLLL''''}}}};;;; $$$$EEEENNNNVVVV{{{{''''IIIIFFFFSSSS''''}}}} ==== '''''''' iiiiffff ddddeeeeffffiiiinnnneeeedddd $$$$EEEENNNNVVVV{{{{''''IIIIFFFFSSSS''''}}}};;;; AAAAUUUUTTTTHHHHOOOORRRR Larry Wall <<_l_w_a_l_l_@_s_e_m_s_._c_o_m>, with the help of oodles of other folks. FFFFIIIILLLLEEEESSSS """"////ttttmmmmpppp////ppppeeeerrrrllll----eeee$$$$$$$$"""" tttteeeemmmmppppoooorrrraaaarrrryyyy ffffiiiilllleeee ffffoooorrrr ----eeee ccccoooommmmmmmmaaaannnnddddssss """"@@@@IIIINNNNCCCC"""" llllooooccccaaaattttiiiioooonnnnssss ooooffff ppppeeeerrrrllll 5555 lllliiiibbbbrrrraaaarrrriiiieeeessss SSSSEEEEEEEE AAAALLLLSSSSOOOO aaaa2222pppp aaaawwwwkkkk ttttoooo ppppeeeerrrrllll ttttrrrraaaannnnssssllllaaaattttoooorrrr ssss2222pppp sssseeeedddd ttttoooo ppppeeeerrrrllll ttttrrrraaaannnnssssllllaaaattttoooorrrr DDDDIIIIAAAAGGGGNNNNOOOOSSSSTTTTIIIICCCCSSSS The ----wwww switch produces some lovely diagnostics. See the _p_e_r_l_d_i_a_g manpage for explanations of all Perl's diagnostics. Compilation errors will tell you the line number of the error, with an indication of the next token or token type that was to be examined. (In the case of a script passed to Perl via ----eeee switches, each ----eeee is counted as one line.) Setuid scripts have additional constraints that can 30/Jan/96 perl 5.002 with 5 PERL(1) User Contributed Perl Documentation PERL(1) produce error messages such as "Insecure dependency". See the _p_e_r_l_s_e_c manpage. Did we mention that you should definitely consider using the ----wwww switch? BBBBUUUUGGGGSSSS The ----wwww switch is not mandatory. Perl is at the mercy of your machine's definitions of various operations such as type casting, _a_t_o_f_(_) and _s_p_r_i_n_t_f_(_). The latter can even trigger a coredump when passed ludicrous input values. If your stdio requires a seek or eof between reads and writes on a particular stream, so does Perl. (This doesn't apply to _s_y_s_r_e_a_d_(_) and _s_y_s_w_r_i_t_e_(_).) While none of the built-in data types have any arbitrary size limits (apart from memory size), there are still a few arbitrary limits: a given identifier may not be longer than 255 characters, and no component of your PATH may be longer than 255 if you use ----SSSS. A regular expression may not compile to more than 32767 bytes internally. See the perl bugs database at _h_t_t_p_:_/_/_p_e_r_l_._c_o_m_/_p_e_r_l_/_b_u_g_s_/. You may mail your bug reports (be sure to include full configuration information as output by the myconfig program in the perl source tree) to _p_e_r_l_b_u_g_@_p_e_r_l_._c_o_m. If you've succeeded in compiling perl, the perlbug script in the utils/ subdirectory can be used to help mail in a bug report. Perl actually stands for Pathologically Eclectic Rubbish Lister, but don't tell anyone I said that. NNNNOOOOTTTTEEEESSSS The Perl motto is "There's more than one way to do it." Divining how many more is left as an exercise to the reader. The three principal virtues of a programmer are Laziness, Impatience, and Hubris. See the Camel Book for why. 30/Jan/96 perl 5.002 with 6