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perlcygwin (1)


perlcygwin - Perl for Cygwin


This document will help you configure, make, test and
install Perl on Cygwin.  This document also describes
features of Cygwin that will affect how Perl behaves at

NOTE: There are pre-built Perl packages available for Cygwin
and a version of Perl is provided in the normal Cygwin
install.  If you do not need to customize the configuration,
consider using one of those packages.


Perl Programmers Reference Guide                    PERLCYGWIN(1)

     README.cygwin - Perl for Cygwin

     This document will help you configure, make, test and
     install Perl on Cygwin.  This document also describes
     features of Cygwin that will affect how Perl behaves at

     NOTE: There are pre-built Perl packages available for Cygwin
     and a version of Perl is provided in the normal Cygwin
     install.  If you do not need to customize the configuration,
     consider using one of those packages.

  Cygwin = GNU+Cygnus+Windows (Don't leave UNIX without it)
     The Cygwin tools are ports of the popular GNU development
     tools for Win32 platforms.  They run thanks to the Cygwin
     library which provides the UNIX system calls and environment
     these programs expect.  More information about this project
     can be found at:


     A recent net or commercial release of Cygwin is required.

     At the time this document was last updated, Cygwin 1.5.24
     was current.

  Cygwin Configuration
     While building Perl some changes may be necessary to your
     Cygwin setup so that Perl builds cleanly.  These changes are
     not required for normal Perl usage.

     NOTE: The binaries that are built will run on all Win32
     versions.  They do not depend on your host system
     (Win9x/WinME, WinNT/Win2K) or your Cygwin configuration
     (ntea, ntsec, binary/text mounts).  The only dependencies
     come from hard-coded pathnames like "/usr/local".  However,
     your host system and Cygwin configuration will affect Perl's
     runtime behavior (see "TEST").

     o   "PATH"

         Set the "PATH" environment variable so that Configure
         finds the Cygwin versions of programs.  Any Windows
         directories should be removed or moved to the end of
         your "PATH".

     o   nroff

         If you do not have nroff (which is part of the groff

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         package), Configure will not prompt you to install man

     o   Permissions

         On WinNT with either the ntea or ntsec "CYGWIN"
         settings, directory and file permissions may not be set
         correctly.  Since the build process creates directories
         and files, to be safe you may want to run a "chmod -R +w
         *" on the entire Perl source tree.

         Also, it is a well known WinNT "feature" that files
         created by a login that is a member of the
         Administrators group will be owned by the Administrators
         group.  Depending on your umask, you may find that you
         can not write to files that you just created (because
         you are no longer the owner).  When using the ntsec
         "CYGWIN" setting, this is not an issue because it
         "corrects" the ownership to what you would expect on a
         UNIX system.

     The default options gathered by Configure with the
     assistance of hints/ will build a Perl that
     supports dynamic loading (which requires a shared

     This will run Configure and keep a record:

       ./Configure 2>&1 | tee log.configure

     If you are willing to accept all the defaults run Configure
     with -de.  However, several useful customizations are

  Stripping Perl Binaries on Cygwin
     It is possible to strip the EXEs and DLLs created by the
     build process.  The resulting binaries will be significantly
     smaller.  If you want the binaries to be stripped, you can
     either add a -s option when Configure prompts you,

       Any additional ld flags (NOT including libraries)? [none] -s
       Any special flags to pass to g++ to create a dynamically loaded library?
       [none] -s
       Any special flags to pass to gcc to use dynamic linking? [none] -s

     or you can edit hints/ and uncomment the relevant
     variables near the end of the file.

  Optional Libraries for Perl on Cygwin
     Several Perl functions and modules depend on the existence
     of some optional libraries.  Configure will find them if

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     they are installed in one of the directories listed as being
     used for library searches.  Pre-built packages for most of
     these are available from the Cygwin installer.

     o   "-lcrypt"

         The crypt package distributed with Cygwin is a Linux
         compatible 56-bit DES crypt port by Corinna Vinschen.

         Alternatively, the crypt libraries in GNU libc have been
         ported to Cygwin.

         The DES based Ultra Fast Crypt port was done by Alexey


         NOTE: There are various export restrictions on DES
         implementations, see the glibc README for more details.

         The MD5 port was done by Andy Piper:


     o   "-lgdbm_compat" ("use GDBM_File")

         GDBM is available for Cygwin.

         NOTE: The GDBM library only works on NTFS partitions.

     o   "-ldb" ("use DB_File")

         BerkeleyDB is available for Cygwin.

         NOTE: The BerkeleyDB library only completely works on
         NTFS partitions and db-4.3 is flawed.

     o   "cygserver" ("use IPC::SysV")

         A port of SysV IPC is available for Cygwin.

         NOTE: This has not been extensively tested.  In
         particular, "d_semctl_semun" is undefined because it
         fails a Configure test and on Win9x the shm*() functions
         seem to hang.  It also creates a compile time dependency
         because perl.h includes <sys/ipc.h> and <sys/sem.h>
         (which will be required in the future when compiling

     o   "-lutil"

         Included with the standard Cygwin netrelease is the

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         inetutils package which includes libutil.a.

  Configure-time Options for Perl on Cygwin
     The INSTALL document describes several Configure-time
     options.  Some of these will work with Cygwin, others are
     not yet possible.  Also, some of these are experimental.
     You can either select an option when Configure prompts you
     or you can define (undefine) symbols on the command line.

     o   "-Uusedl"

         Undefining this symbol forces Perl to be compiled

     o   "-Uusemymalloc"

         By default Perl uses the "malloc()" included with the
         Perl source.  If you want to force Perl to build with
         the system "malloc()" undefine this symbol.

     o   "-Uuseperlio"

         Undefining this symbol disables the PerlIO abstraction.
         PerlIO is now the default; it is not recommended to
         disable PerlIO.

     o   "-Dusemultiplicity"

         Multiplicity is required when embedding Perl in a C
         program and using more than one interpreter instance.
         This works with the Cygwin port.

     o   "-Duse64bitint"

         By default Perl uses 32 bit integers.  If you want to
         use larger 64 bit integers, define this symbol.

     o   "-Duselongdouble"

         gcc supports long doubles (12 bytes).  However, several
         additional long double math functions are necessary to
         use them within Perl ({atan2, cos, exp, floor, fmod,
         frexp, isnan, log, modf, pow, sin, sqrt}l, strtold).
         These are not yet available with Cygwin.

     o   "-Dusethreads"

         POSIX threads are implemented in Cygwin, define this
         symbol if you want a threaded perl.

     o   "-Duselargefiles"

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         Cygwin uses 64-bit integers for internal size and
         position calculations, this will be correctly detected
         and defined by Configure.

     o   "-Dmksymlinks"

         Use this to build perl outside of the source tree.  This
         works with Cygwin.  Details can be found in the INSTALL
         document.  This is the recommended way to build perl
         from sources.

  Suspicious Warnings on Cygwin
     You may see some messages during Configure that seem

     o   Win9x and "d_eofnblk"

         Win9x does not correctly report "EOF" with a non-
         blocking read on a closed pipe.  You will see the
         following messages:

           But it also returns -1 to signal EOF, so be careful!
           WARNING: you can't distinguish between EOF and no data!

           *** WHOA THERE!!! ***
               The recommended value for $d_eofnblk on this machine was "define"!
               Keep the recommended value? [y]

         At least for consistency with WinNT, you should keep the
         recommended value.

     o   Compiler/Preprocessor defines

         The following error occurs because of the Cygwin
         "#define" of "_LONG_DOUBLE":

           Guessing which symbols your C compiler and preprocessor define...
           try.c:<line#>: missing binary operator

         This failure does not seem to cause any problems.  With
         older gcc versions, "parse error" is reported instead of
         "missing binary operator".

     Simply run make and wait:

       make 2>&1 | tee log.make

     There are two steps to running the test suite:

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       make test 2>&1 | tee log.make-test

       cd t; ./perl harness 2>&1 | tee ../log.harness

     The same tests are run both times, but more information is
     provided when running as "./perl harness".

     Test results vary depending on your host system and your
     Cygwin configuration.  If a test can pass in some Cygwin
     setup, it is always attempted and explainable test failures
     are documented.  It is possible for Perl to pass all the
     tests, but it is more likely that some tests will fail for
     one of the reasons listed below.

  File Permissions on Cygwin
     UNIX file permissions are based on sets of mode bits for
     {read,write,execute} for each {user,group,other}.  By
     default Cygwin only tracks the Win32 read-only attribute
     represented as the UNIX file user write bit (files are
     always readable, files are executable if they have a
     .{com,bat,exe} extension or begin with "#!", directories are
     always readable and executable).  On WinNT with the ntea
     "CYGWIN" setting, the additional mode bits are stored as
     extended file attributes.  On WinNT with the default ntsec
     "CYGWIN" setting, permissions use the standard WinNT
     security descriptors and access control lists. Without one
     of these options, these tests will fail (listing not updated

       Failed Test           List of failed
       io/fs.t               5, 7, 9-10
       lib/anydbm.t          2
       lib/db-btree.t        20
       lib/db-hash.t         16
       lib/db-recno.t        18
       lib/gdbm.t            2
       lib/ndbm.t            2
       lib/odbm.t            2
       lib/sdbm.t            2
       op/stat.t             9, 20 (.tmp not an executable extension)

  NDBM_File and ODBM_File do not work on FAT filesystems
     Do not use NDBM_File or ODBM_File on FAT filesystem.  They
     can be built on a FAT filesystem, but many tests will fail:

      ../ext/NDBM_File/ndbm.t       13  3328    71   59  83.10%  1-2 4 16-71
      ../ext/ODBM_File/odbm.t      255 65280    ??   ??       %  ??
      ../lib/AnyDBM_File.t           2   512    12    2  16.67%  1 4
      ../lib/Memoize/t/errors.t      0   139    11    5  45.45%  7-11
      ../lib/Memoize/t/tie_ndbm.t   13  3328     4    4 100.00%  1-4
      run/fresh_perl.t                          97    1   1.03%  91

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     If you intend to run only on FAT (or if using AnyDBM_File on
     FAT), run Configure with the -Ui_ndbm and -Ui_dbm options to
     prevent NDBM_File and ODBM_File being built.

     With NTFS (and no CYGWIN=nontsec), there should be no
     problems even if perl was built on FAT.

  "fork()" failures in io_* tests
     A "fork()" failure may result in the following tests


     See comment on fork in Miscellaneous below.

Specific features of the Cygwin port
  Script Portability on Cygwin
     Cygwin does an outstanding job of providing UNIX-like
     semantics on top of Win32 systems.  However, in addition to
     the items noted above, there are some differences that you
     should know about.  This is a very brief guide to
     portability, more information can be found in the Cygwin

     o   Pathnames

         Cygwin pathnames can be separated by forward (/) or
         backward (\\) slashes.  They may also begin with drive
         letters (C:) or Universal Naming Codes (//UNC).  DOS
         device names (aux, con, prn, com*, lpt?, nul) are
         invalid as base filenames.  However, they can be used in
         extensions (e.g., hello.aux).  Names may contain all
         printable characters except these:

           : * ? " < > |

         File names are case insensitive, but case preserving.  A
         pathname that contains a backslash or drive letter is a
         Win32 pathname (and not subject to the translations
         applied to POSIX style pathnames).

         For conversion we have "Cygwin::win_to_posix_path()" and

         Pathnames may not contain Unicode characters. "Cygwin"
         still uses the ANSI API calls and no Unicode calls
         because of newlib deficiencies.  There's an unofficial
         unicode patch for cygwin at

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     o   Text/Binary

         When a file is opened it is in either text or binary
         mode.  In text mode a file is subject to CR/LF/Ctrl-Z
         translations.  With Cygwin, the default mode for an
         "open()" is determined by the mode of the mount that
         underlies the file. See "Cygwin::is_binmount()". Perl
         provides a "binmode()" function to set binary mode on
         files that otherwise would be treated as text.
         "sysopen()" with the "O_TEXT" flag sets text mode on
         files that otherwise would be treated as binary:

             sysopen(FOO, "bar", O_WRONLY|O_CREAT|O_TEXT)

         "lseek()", "tell()" and "sysseek()" only work with files
         opened in binary mode.

         The text/binary issue is covered at length in the Cygwin

     o   PerlIO

         PerlIO overrides the default Cygwin Text/Binary
         behaviour.  A file will always be treated as binary,
         regardless of the mode of the mount it lives on, just
         like it is in UNIX.  So CR/LF translation needs to be
         requested in either the "open()" call like this:

           open(FH, ">:crlf", "out.txt");

         which will do conversion from LF to CR/LF on the output,
         or in the environment settings (add this to your

           export PERLIO=crlf

         which will pull in the crlf PerlIO layer which does LF
         -> CRLF conversion on every output generated by perl.

     o   .exe

         The Cygwin "stat()", "lstat()" and "readlink()"
         functions make the .exe extension transparent by looking
         for foo.exe when you ask for foo (unless a foo also
         exists).  Cygwin does not require a .exe extension, but
         gcc adds it automatically when building a program.
         However, when accessing an executable as a normal file
         (e.g., cp in a makefile) the .exe is not transparent.
         The install included with Cygwin automatically appends a
         .exe when necessary.

     o   Cygwin vs. Windows process ids

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         Cygwin processes have their own pid, which is different
         from the underlying windows pid.  Most posix compliant
         Proc functions expect the cygwin pid, but several
         Win32::Process functions expect the winpid. E.g. $$ is
         the cygwin pid of /usr/bin/perl, which is not the
         winpid.  Use "Cygwin::winpid_to_pid()" and
         "Cygwin::winpid_to_pid()" to translate between them.

     o   Cygwin vs. Windows errors

         Under Cygwin, $^E is the same as $!.  When using Win32
         API Functions, use "Win32::GetLastError()" to get the
         last Windows error.

     o   "chown()"

         On WinNT "chown()" can change a file's user and group
         IDs.  On Win9x "chown()" is a no-op, although this is
         appropriate since there is no security model.

     o   Miscellaneous

         File locking using the "F_GETLK" command to "fcntl()" is
         a stub that returns "ENOSYS".

         Win9x can not "rename()" an open file (although WinNT

         The Cygwin "chroot()" implementation has holes (it can
         not restrict file access by native Win32 programs).

         Inplace editing "perl -i" of files doesn't work without
         doing a backup of the file being edited "perl -i.bak"
         because of windowish restrictions, therefore Perl adds
         the suffix ".bak" automatically if you use "perl -i"
         without specifying a backup extension.

         Using "fork()" after loading multiple dlls may fail with
         an internal cygwin error like the following:

           C:\CYGWIN\BIN\PERL.EXE: *** couldn't allocate memory 0x10000(4128768) for 'C:\CYGWIN\LIB\PERL5\5.6.1\CYGWIN-MULTI\AUTO\SOCKET\SOCKET.DLL' alignment, Win32 error 8

             200 [main] perl 377147 sync_with_child: child -395691(0xB8) died before initialization with status code 0x1
            1370 [main] perl 377147 sync_with_child: *** child state child loading dlls

         Use the rebase utility to resolve the conflicting dll
         addresses.  The rebase package is included in the Cygwin
         netrelease.  Use setup.exe from to install it and run

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  Prebuilt methods:
         Returns the current working directory.

         Translates a cygwin pid to the corresponding Windows pid
         (which may or may not be the same).

         Translates a Windows pid to the corresponding cygwin pid
         (if any).

         Translates a Windows path to the corresponding cygwin
         path respecting the current mount points. With a second
         non-null argument returns an absolute path. Double-byte
         characters will not be translated.

         Translates a cygwin path to the corresponding cygwin
         path respecting the current mount points. With a second
         non-null argument returns an absolute path. Double-byte
         characters will not be translated.

         Returns an array of [mnt_dir, mnt_fsname, mnt_type,

           perl -e 'for $i (Cygwin::mount_table) {print join(" ",@$i),"\n";}'
           /bin c:\cygwin\bin system binmode,cygexec
           /usr/bin c:\cygwin\bin system binmode
           /usr/lib c:\cygwin\lib system binmode
           / c:\cygwin system binmode
           /cygdrive/c c: system binmode,noumount
           /cygdrive/d d: system binmode,noumount
           /cygdrive/e e: system binmode,noumount

         Returns the mount type and flags for a specified mount
         point.  A comma-separated string of mntent->mnt_type
         (always "system" or "user"), then the mntent->mnt_opts,
         where the first is always "binmode" or "textmode".


         If the argument is "/cygdrive", then just the volume
         mount settings, and the cygdrive mount prefix are

         User mounts override system mounts.

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           $ perl -e 'print Cygwin::mount_flags "/usr/bin"'
           $ perl -e 'print Cygwin::mount_flags "/cygdrive"'

         Returns true if the given cygwin path is binary mounted,
         false if the path is mounted in textmode.

     This will install Perl, including man pages.

       make install 2>&1 | tee log.make-install

     NOTE: If "STDERR" is redirected "make install" will not
     prompt you to install perl into /usr/bin.

     You may need to be Administrator to run "make install".  If
     you are not, you must have write access to the directories
     in question.

     Information on installing the Perl documentation in HTML
     format can be found in the INSTALL document.

     These are the files in the Perl release that contain
     references to Cygwin.  These very brief notes attempt to
     explain the reason for all conditional code.  Hopefully,
     keeping this up to date will allow the Cygwin port to be
     kept as clean as possible.

           INSTALL README.cygwin README.win32 MANIFEST
           pod/perl.pod pod/perlport.pod pod/perlfaq3.pod
           pod/perldelta.pod pod/perl5004delta.pod pod/perl56delta.pod
           pod/perl561delta.pod pod/perl570delta.pod pod/perl572delta.pod
           pod/perl573delta.pod pod/perl58delta.pod pod/perl581delta.pod
           pod/perl590delta.pod pod/perlhist.pod pod/perlmodlib.pod
           pod/perltoc.pod pod.lst Porting/Glossary pod/perlrepository.pod
           ext/Compress-Raw-Zlib/Changes ext/Compress-Raw-Zlib/README
           ext/Compress-Zlib/Changes cpan/Cwd/Changes ext/DB_File/Changes
           ext/Encode/Changes ext/Sys-Syslog/Changes ext/Time-HiRes/Changes
           ext/Win32API-File/Changes lib/CGI/Changes lib/ExtUtils/CBuilder/Changes
           lib/ExtUtils/Changes lib/ExtUtils/NOTES lib/ExtUtils/PATCHING
           lib/ExtUtils/README lib/Module/Build/Changes lib/Net/Ping/Changes
           lib/Term/ANSIColor/ChangeLog lib/Term/ANSIColor/README
           README.symbian symbian/TODO

     Build, Configure, Make, Install

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           Configure             - help finding hints from uname,
                                   shared libperl required for dynamic loading
           Makefile.SH Cross/Makefile-cross-SH
                                 - linklibperl
           Porting/patchls       - cygwin in port list
           installman            - man pages with :: translated to .
           installperl           - install dll, install to 'pods'
           makedepend.SH         - uwinfix
           - file permissions

           symbian/ symbian/
           win32/Makefile win32/

           t/io/fs.t             - no file mode checks if not ntsec
                                   skip rename() check when not check_case:relaxed
           t/io/tell.t           - binmode
           t/lib/cygwin.t        - builtin cygwin function tests
           t/op/groups.t         - basegroup has ID = 0
           t/op/magic.t          - $^X/symlink WORKAROUND, s/.exe//
           t/op/stat.t           - no /dev, skip Win32 ftCreationTime quirk
                                   (cache manager sometimes preserves ctime of file
                                   previously created and deleted), no -u (setuid)
           t/op/taint.t          - can't use empty path under Cygwin Perl
           t/op/time.t           - no tzset()

     Compiled Perl Source
           EXTERN.h              - __declspec(dllimport)
           XSUB.h                - __declspec(dllexport)
           cygwin/cygwin.c       - os_extras (getcwd, spawn, and several Cygwin:: functions)
           perl.c                - os_extras, -i.bak
           perl.h                - binmode
           doio.c                - win9x can not rename a file when it is open
           pp_sys.c              - do not define h_errno, init _pwent_struct.pw_comment
           util.c                - use setenv
           util.h                - PERL_FILE_IS_ABSOLUTE macro
           pp.c                  - Comment about Posix vs IEEE math under Cygwin
           perlio.c              - CR/LF mode
           perliol.c             - Comment about EXTCONST under Cygwin

     Compiled Module Source

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                                 - Can't install via CPAN shell under Cygwin
                                 - Cygwin is Unix-like and has vsnprintf
           ext/Errno/Errno_pm.PL - Special handling for Win32 Perl under Cygwin
           ext/POSIX/POSIX.xs    - tzname defined externally
                                 - EXTCONST needs to be redefined from EXTERN.h
                                 - binary open
                                 - Cygwin has syslog.h
                                 - Convert paths to Windows paths
                                 - Various timers not available
                                 - Find w32api/windows.h
           ext/Win32/Makefile.PL - Use various libraries under Cygwin
           ext/Win32/Win32.xs    - Child dir and child env under Cygwin
                                 - _open_osfhandle not implemented under Cygwin
                                 - __declspec(dllexport)

     Perl Modules/Scripts
           ext/B/t/ - Comment about stderr/stdout order under Cygwin
                                 - Use binary mode under Cygwin
                                 - Convert paths to Windows paths
                                 - Comment about various timers not available
                                 - _open_osfhandle not implemented under Cygwin
                                 - History of Win32CORE under Cygwin
           lib/            - binmode and path separator
           lib/CPANPLUS/Dist/ - Commented out code that fails under Win32/Cygwin
                                 - OS classifications
                                 - Contants for Cygwin
                                 - Example of Cygwin report
                                 - Abort if running on old Cygwin version
           lib/            - hook to internal Cwd::cwd
                                 - use gcc for ld, and link to libperl.dll.a
                                 - Cygwin is Unix-like

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           lib/ExtUtils/ - Install and rename issues under Cygwin
           lib/ExtUtils/    - OS classifications
           lib/ExtUtils/ - Example for Cygwin
                                 - require
                                 - canonpath, cflags, manifypods, perl_archive
           lib/File/     - Comment about quotes using a Cygwin example
           lib/File/      - on remote drives stat() always sets st_nlink to 1
           lib/File/Spec/ - case_tolerant
           lib/File/Spec/ - preserve //unc
           lib/File/Spec/ - References a message on
           lib/File/      - Pulls in lib/File/Spec/
           lib/File/      - no directory sticky bit
           lib/Module/Build/ - Comment references 'make' under Cygwin
                                 - Use '.' for man page separator
           lib/Module/   - Cygwin is Unix-like
           lib/Module/ - List of all module files and versions
           lib/Net/     - No domainname command under Cygwin
           lib/Net/      - Bypass using stat() under Cygwin
           lib/Net/       - ECONREFUSED is EAGAIN under Cygwin
           lib/Pod/       - Set 'pods' dir
           lib/Pod/Perldoc/ - '-c' switch for pod2man
           lib/Pod/    - Use 'less' pager, and use .exe extension
           lib/Term/ - Cygwin terminal info
           lib/        - use stdin not /dev/tty
           utils/perlbug.PL      - Add CYGWIN environment variable to report

     Perl Module Tests

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     Support for swapping real and effective user and group IDs
     is incomplete.  On WinNT Cygwin provides "setuid()",
     "seteuid()", "setgid()" and "setegid()".  However,
     additional Cygwin calls for manipulating WinNT access tokens
     and security contexts are required.

     Charles Wilson <>, Eric Fifer
     <>, alexander smishlajev
     <>, Steven Morlock <>,
     Sebastien Barre <>, Teun Burgers
     <>, Gerrit P. Haase <>,
     Reini Urban <>, Jan Dubois
     <>, Jerry D. Hedden <>.

     Last updated: 2007-09-25

     See attributes(5) for descriptions of the following

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Perl Programmers Reference Guide                    PERLCYGWIN(1)

     |Availability   | runtime/perl-512 |
     |Stability      | Uncommitted      |
     This software was built from source available at  The original
     community source was downloaded from

     Further information about this software can be found on the
     open source community website at

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