实用报表提取语言 Perl : Practical Extraction and Report Language

Perl 最初的设计者为 拉里·沃尔(Larry Wall),他于1987年12月18日发表。Perl借取了C、sed、awk、shell scripting以及很多其他程序语言的特性。其中最重要的特性是它内部集成了 正则表达式的功能,以及巨大的第三方代码库CPAN。简而言之,Perl象C一样强大,象awk、sed等 脚本描述语言一样方便。Perl 一般被称为“实用报表提取语言”(Practical Extraction and Report Language),你也可能看到“perl”,所有的字母都是小写的。一般,“Perl”,有大写的 P,是指语言本身,而“perl”,小写的 p,是指程序运行的 解释器
 
perl的前身是Unix系统管理的一个工具,被用在无数的小任务里。后逐渐发展成为一种功能强大的程序设计语言,用作Web编程、数据库处理、XML处理以及系统管理;在完成这些工作时,同时仍能处理日常细小工作,这是它的设计初衷。Perl特别适合系统管理和Web编程。实际上已经被用在所有Unix(包括Linux)捆绑在一起作为标准部件发布,同时也用在Microsoft Windows和几乎其他所有操作系统。Perl的应用很广泛,依靠Perl工作更容易、更有效。
 

NAME
    perl - Practical Extraction and Report Language

SYNOPSIS
    perl [ -sTtuUWX ] [ -hv ] [ -V[:*configvar*] ]
    [ -cw ] [ -d[t][:*debugger*] ] [ -D[*number/list*] ]
    [ -pna ] [ -F*pattern* ] [ -l[*octal*] ] [ -0[*octal/hexadecimal*] ]
    [ -I*dir* ] [ -m[-]*module* ] [ -M[-]*'module...'* ] [ -f ]
    [ -C [*number/list*] ] [ -P ] [ -S ] [ -x[*dir*] ] [ -i[*extension*] ]
    [ -e *'command'* ] [ -- ] [ *programfile* ] [ *argument* ]...

    If you're new to Perl, you should start with perlintro, which is a
    general intro for beginners and provides some background to help you
    navigate the rest of Perl's extensive documentation.

    For ease of access, the Perl manual has been split up into several
    sections.

  Overview
        perl                Perl overview (this section)
        perlintro           Perl introduction for beginners
        perltoc             Perl documentation table of contents

        ActivePerl          ActivePerl overview

  Tutorials
        perlreftut          Perl references short introduction
        perldsc             Perl data structures intro
        perllol             Perl data structures: arrays of arrays

        perlrequick         Perl regular expressions quick start
        perlretut           Perl regular expressions tutorial

        perlboot            Perl OO tutorial for beginners
        perltoot            Perl OO tutorial, part 1
        perltooc            Perl OO tutorial, part 2
        perlbot             Perl OO tricks and examples

        perlstyle           Perl style guide

        perlcheat           Perl cheat sheet
        perltrap            Perl traps for the unwary
        perldebtut          Perl debugging tutorial

        perlfaq             Perl frequently asked questions
          perlfaq1          General Questions About Perl
          perlfaq2          Obtaining and Learning about Perl
          perlfaq3          Programming Tools
          perlfaq4          Data Manipulation
          perlfaq5          Files and Formats
          perlfaq6          Regexes
          perlfaq7          Perl Language Issues
          perlfaq8          System Interaction
          perlfaq9          Networking

  Reference Manual
        perlsyn             Perl syntax
        perldata            Perl data structures
        perlop              Perl operators and precedence
        perlsub             Perl subroutines
        perlfunc            Perl built-in functions
          perlopentut       Perl open() tutorial
          perlpacktut       Perl pack() and unpack() tutorial
        perlpod             Perl plain old documentation
        perlpodspec         Perl plain old documentation format specification
        perlrun             Perl execution and options
        perldiag            Perl diagnostic messages
        perllexwarn         Perl warnings and their control
        perldebug           Perl debugging
        perlvar             Perl predefined variables
        perlre              Perl regular expressions, the rest of the story
        perlreref           Perl regular expressions quick reference
        perlref             Perl references, the rest of the story
        perlform            Perl formats
        perlobj             Perl objects
        perltie             Perl objects hidden behind simple variables
          perldbmfilter     Perl DBM filters

        perlipc             Perl interprocess communication
        perlfork            Perl fork() information
        perlnumber          Perl number semantics

        perlthrtut          Perl threads tutorial
          perlothrtut       Old Perl threads tutorial

        perlport            Perl portability guide
        perllocale          Perl locale support
        perluniintro        Perl Unicode introduction
        perlunicode         Perl Unicode support
        perlebcdic          Considerations for running Perl on EBCDIC platforms

        perlsec             Perl security

        perlmod             Perl modules: how they work
        perlmodlib          Perl modules: how to write and use
        perlmodstyle        Perl modules: how to write modules with style
        perlmodinstall      Perl modules: how to install from CPAN
        perlnewmod          Perl modules: preparing a new module for distribution

        perlutil            utilities packaged with the Perl distribution

        perlcompile         Perl compiler suite intro

        perlfilter          Perl source filters

        perlglossary        Perl Glossary

  Internals and C Language Interface
        perlembed           Perl ways to embed perl in your C or C++ application
        perldebguts         Perl debugging guts and tips
        perlxstut           Perl XS tutorial
        perlxs              Perl XS application programming interface
        perlclib            Internal replacements for standard C library functions
        perlguts            Perl internal functions for those doing extensions
        perlcall            Perl calling conventions from C

        perlapi             Perl API listing (autogenerated)
        perlintern          Perl internal functions (autogenerated)
        perliol             C API for Perl's implementation of IO in Layers
        perlapio            Perl internal IO abstraction interface

        perlhack            Perl hackers guide

  Miscellaneous
        perlbook            Perl book information
        perltodo            Perl things to do

        perldoc             Look up Perl documentation in Pod format

        perlhist            Perl history records
        perldelta           Perl changes since previous version
        perl587delta        Perl changes in version 5.8.7
        perl586delta        Perl changes in version 5.8.6
        perl585delta        Perl changes in version 5.8.5
        perl584delta        Perl changes in version 5.8.4
        perl583delta        Perl changes in version 5.8.3
        perl582delta        Perl changes in version 5.8.2
        perl581delta        Perl changes in version 5.8.1
        perl58delta         Perl changes in version 5.8.0
        perl573delta        Perl changes in version 5.7.3
        perl572delta        Perl changes in version 5.7.2
        perl571delta        Perl changes in version 5.7.1
        perl570delta        Perl changes in version 5.7.0
        perl561delta        Perl changes in version 5.6.1
        perl56delta         Perl changes in version 5.6
        perl5005delta       Perl changes in version 5.005
        perl5004delta       Perl changes in version 5.004

        activeperl-release  Release notes for ActivePerl
        activeperl-changes  ActivePerl revision history

        perlartistic        Perl Artistic License
        perlgpl             GNU General Public License

  Language-Specific
        perlcn              Perl for Simplified Chinese (in EUC-CN)
        perljp              Perl for Japanese (in EUC-JP)
        perlko              Perl for Korean (in EUC-KR)
        perltw              Perl for Traditional Chinese (in Big5)

  Platform-Specific
        perlaix             Perl notes for AIX
        perlamiga           Perl notes for AmigaOS
        perlapollo          Perl notes for Apollo DomainOS
        perlbeos            Perl notes for BeOS
        perlbs2000          Perl notes for POSIX-BC BS2000
        perlce              Perl notes for WinCE
        perlcygwin          Perl notes for Cygwin
        perldgux            Perl notes for DG/UX
        perldos             Perl notes for DOS
        perlepoc            Perl notes for EPOC
        perlfreebsd         Perl notes for FreeBSD
        perlhpux            Perl notes for HP-UX
        perlhurd            Perl notes for Hurd
        perlirix            Perl notes for Irix
        perllinux           Perl notes for Linux
        perlmachten         Perl notes for Power MachTen
        perlmacos           Perl notes for Mac OS (Classic)
        perlmacosx          Perl notes for Mac OS X
        perlmint            Perl notes for MiNT
        perlmpeix           Perl notes for MPE/iX
        perlnetware         Perl notes for NetWare
        perlopenbsd         Perl notes for OpenBSD
        perlos2             Perl notes for OS/2
        perlos390           Perl notes for OS/390
        perlos400           Perl notes for OS/400
        perlplan9           Perl notes for Plan 9
        perlqnx             Perl notes for QNX
        perlsolaris         Perl notes for Solaris
        perltru64           Perl notes for Tru64
        perluts             Perl notes for UTS
        perlvmesa           Perl notes for VM/ESA
        perlvms             Perl notes for VMS
        perlvos             Perl notes for Stratus VOS
        perlwin32           Perl notes for Windows

    By default, the manpages listed above are installed in the
    /usr/local/man/ directory.

    Extensive additional documentation for Perl modules is available. The
    default configuration for perl will place this additional documentation
    in the /usr/local/lib/perl5/man directory (or else in the man
    subdirectory of the Perl library directory). Some of this additional
    documentation is distributed standard with Perl, but you'll also find
    documentation for third-party modules there.

    You should be able to view Perl's documentation with your man(1) program
    by including the proper directories in the appropriate start-up files,
    or in the MANPATH environment variable. To find out where the
    configuration has installed the manpages, type:

        perl -V:man.dir

    If the directories have a common stem, such as /usr/local/man/man1 and
    /usr/local/man/man3, you need only to add that stem (/usr/local/man) to
    your man(1) configuration files or your MANPATH environment variable. If
    they do not share a stem, you'll have to add both stems.

    If that doesn't work for some reason, you can still use the supplied
    perldoc 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 -w switch first. It will
    often point out exactly where the trouble is.

DESCRIPTION
    Perl is a 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).

    Perl combines (in the author's opinion, anyway) some of the best
    features of C, sed, awk, and sh, so people familiar with those languages
    should have little difficulty with it. (Language historians will also
    note some vestiges of csh, Pascal, and even BASIC-PLUS.) Expression
    syntax corresponds 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 tables used by hashes
    (sometimes called "associative arrays") grow as necessary to prevent
    degraded performance. Perl can use sophisticated pattern matching
    techniques to scan large amounts of data quickly. Although optimized for
    scanning text, Perl can also deal with binary data, and can make dbm
    files look like hashes. Setuid Perl scripts are safer than C programs
    through a dataflow tracing mechanism that prevents many stupid security
    holes.

    If you have a problem that would ordinarily use sed or awk or sh, 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 sed and awk scripts into Perl scripts.

    But wait, there's more...

    Begun in 1993 (see perlhist), Perl version 5 is nearly a complete
    rewrite that provides the following additional benefits:

    *   modularity and reusability using innumerable modules

        Described in perlmod, perlmodlib, and perlmodinstall.

    *   embeddable and extensible

        Described in perlembed, perlxstut, perlxs, perlcall, perlguts, and
        xsubpp.

    *   roll-your-own magic variables (including multiple simultaneous DBM
        implementations)

        Described in perltie and AnyDBM_File.

    *   subroutines can now be overridden, autoloaded, and prototyped

        Described in perlsub.

    *   arbitrarily nested data structures and anonymous functions

        Described in perlreftut, perlref, perldsc, and perllol.

    *   object-oriented programming

        Described in perlobj, perlboot, perltoot, perltooc, and perlbot.

    *   support for light-weight processes (threads)

        Described in perlthrtut and threads.

    *   support for Unicode, internationalization, and localization

        Described in perluniintro, perllocale and Locale::Maketext.

    *   lexical scoping

        Described in perlsub.

    *   regular expression enhancements

        Described in perlre, with additional examples in perlop.

    *   enhanced debugger and interactive Perl environment, with integrated
        editor support

        Described in perldebtut, perldebug and perldebguts.

    *   POSIX 1003.1 compliant library

        Described in POSIX.

    Okay, that's *definitely* enough hype.

AVAILABILITY
    Perl is available for most operating systems, including virtually all
    Unix-like platforms. See "Supported Platforms" in perlport for a
    listing.

ENVIRONMENT
    See perlrun.

AUTHOR
    Larry Wall <[email protected]>, with the help of oodles of other folks.

    If your Perl success stories and testimonials may be of help to others
    who wish to advocate the use of Perl in their applications, or if you
    wish to simply express your gratitude to Larry and the Perl developers,
    please write to [email protected] .

FILES
     "@INC"                 locations of perl libraries

SEE ALSO
     a2p    awk to perl translator
     s2p    sed to perl translator

     http://www.perl.org/       the Perl homepage
     http://www.perl.com/       Perl articles (O'Reilly)
     http://www.cpan.org/       the Comprehensive Perl Archive
     http://www.pm.org/         the Perl Mongers

DIAGNOSTICS
    The "use warnings" pragma (and the -w switch) produces some lovely
    diagnostics.

    See perldiag for explanations of all Perl's diagnostics. The "use
    diagnostics" pragma automatically turns Perl's normally terse warnings
    and errors into these longer forms.

    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
    a script passed to Perl via -e switches, each -e is counted as one
    line.)

    Setuid scripts have additional constraints that can produce error
    messages such as "Insecure dependency". See perlsec.

    Did we mention that you should definitely consider using the -w switch?

BUGS
    The -w switch is not mandatory.

    Perl is at the mercy of your machine's definitions of various operations
    such as type casting, atof(), and floating-point output with sprintf().

    If your stdio requires a seek or eof between reads and writes on a
    particular stream, so does Perl. (This doesn't apply to sysread() and
    syswrite().)

    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 variable name may not be longer than 251 characters. Line numbers
    displayed by diagnostics are internally stored as short integers, so
    they are limited to a maximum of 65535 (higher numbers usually being
    affected by wraparound).

    You may mail your bug reports (be sure to include full configuration
    information as output by the myconfig program in the perl source tree,
    or by "perl -V") to [email protected] . 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.

NOTES
    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.

 

 

你可能感兴趣的:(Practical)