Provided by: perl-doc_5.18.2-2ubuntu1_all bug


       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 runtime.

       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 1.7.16 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 (WinXP/Win2K/Win7) or your Cygwin configuration (binary/text mounts,
       cvgserver).  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").

       ·   "PATH"

           Set the "PATH" environment variable so that Configure finds the Cygwin versions of
           programs. Any not-needed Windows directories should be removed or moved to the end of
           your "PATH".

       ·   nroff

           If you do not have nroff (which is part of the groff package), Configure will not
           prompt you to install man pages.


       The default options gathered by Configure with the assistance of hints/ will
       build a Perl that supports dynamic loading (which requires a shared cygperl5_16.dll).

       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 available.

   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

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

       ·   "-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.

       ·   "-lgdbm_compat" ("use GDBM_File")

           GDBM is available for Cygwin.

           NOTE: The GDBM library only works on NTFS partitions.

       ·   "-ldb" ("use DB_File")

           BerkeleyDB is available for Cygwin.

           NOTE: The BerkeleyDB library only completely works on NTFS partitions.

       ·   "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 CPAN modules).

       ·   "-lutil"

           Included with the standard Cygwin netrelease is the inetutils package which includes

   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.

       ·   "-Uusedl"

           Undefining this symbol forces Perl to be compiled statically.

       ·   "-Dusemymalloc"

           By default Perl does not use the "malloc()" included with the Perl source, because it
           was slower and not entirely thread-safe.  If you want to force Perl to build with the
           old -Dusemymalloc define this.

       ·   "-Uuseperlio"

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

       ·   "-Dusemultiplicity"

           Multiplicity is required when embedding Perl in a C program and using more than one
           interpreter instance.  This is only required when you build a not-threaded perl with

       ·   "-Uuse64bitint"

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

       ·   "-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
           newlib, the Cygwin libc.

       ·   "-Uuseithreads"

           Define this symbol if you want not-threaded faster perl.

       ·   "-Duselargefiles"

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

       ·   "-Dmksymlinks"

           Use this to build perl outside of the source tree.  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 suspicious.

       ·   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.

       ·   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:

         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

       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

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


       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 documentation.

       ·   Pathnames

           Cygwin pathnames are separated by forward (/) slashes, Universal Naming Codes (//UNC)
           are also supported Since cygwin-1.7 non-POSIX pathnames are discouraged.  Names may
           contain all printable characters.

           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, but cygwin will warn you, so better convert them to

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

           Since cygwin-1.7 pathnames are UTF-8 encoded.

       ·   Text/Binary

           Since cygwin-1.7 textmounts are deprecated and strongly discouraged.

           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 documentation.

       ·   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

             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 .bashrc):

             export PERLIO=crlf

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

       ·   .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 program included with Cygwin
           automatically appends a .exe when necessary.

       ·   Cygwin vs. Windows process ids

           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.

       ·   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.

       ·   rebase errors on fork or system

           Using "fork()" or "system()" out to another perl after loading multiple dlls may
           result on a DLL baseaddress conflict. The internal cygwin error looks like like the

             0 [main] perl 8916 child_info_fork::abort: data segment start: parent
             (0xC1A000) != child(0xA6A000)


             183 [main] perl 3588 C:\cygwin\bin\perl.exe: *** fatal error - unable to remap C:\cygwin\bin\cygsvn_subr-1-0.dll to same address as parent(0x6FB30000) != 0x6FE60000
             46 [main] perl 3488 fork: child 3588 - died waiting for dll loading, errno11

           See <> It helps
           if not too many DLLs are loaded in memory so the available address space is larger,
           e.g. stopping the MS Internet Explorer might help.

           Use the perlrebase or rebase utilities to resolve the conflicting dll addresses.  The
           rebase package is included in the Cygwin setup. Use setup.exe from
           <> to install it.

           1. kill all perl processes and run "perlrebase" or

           2. kill all cygwin processes and services, start dash from cmd.exe and run

       ·   "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.

       ·   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 can).

           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

   Prebuilt methods:
           Returns the current working directory.

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

           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, mnt_opts].

             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 returned.

           User mounts override system mounts.

             $ 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.

           Cygwin does not initialize all original Win32 environment variables.  See the bottom
           of this page <> for "Restricted Win32

           Certain Win32 programs called from cygwin programs might need some environment
           variable, such as e.g. ADODB needs %COMMONPROGRAMFILES%.  Call Cygwin::sync_winenv()
           to copy all Win32 environment variables to your process and note that cygwin will warn
           on every encounter of non-POSIX paths.


       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

       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 Porting/Glossary pod/perlgit.pod
             dist/Cwd/Changes ext/Compress-Raw-Zlib/Changes
             ext/Compress-Raw-Zlib/README ext/Compress-Zlib/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/Test/Harness/Changes
             lib/Term/ANSIColor/ChangeLog lib/Term/ANSIColor/README README.symbian

       Build, Configure, Make, Install
             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
                                   - 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
                                   - Constants 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
             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


       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: 2012-02-08