*nixish shell (like F<sh.exe> supplied in the binary distribution),
you need to follow the syntax specified in L<perlrun/"Switches">.
+Note that B<-S> switch enables a search with additional extensions
+F<.cmd>, F<.btm>, F<.bat>, F<.pl> as well.
+
=head2 Starting OS/2 (and DOS) programs under Perl
This is what system() (see L<perlfunc/system>), C<``> (see
L<"Frequently asked questions">), and perl should be able to find it
(see L<"PERL_SH_DIR">).
-The only cases when the shell is not used is the multi-argument
-system() (see L<perlfunc/system>)/exec() (see L<perlfunc/exec>), and
-one-argument version thereof without redirection and shell
-meta-characters.
+The cases when the shell is used are:
+
+=over
+
+=item 1
+
+One-argument system() (see L<perlfunc/system>), exec() (see L<perlfunc/exec>)
+with redirection or shell meta-characters;
+
+=item 2
+
+Pipe-open (see L<perlfunc/open>) with the command which contains redirection
+or shell meta-characters;
+
+=item 3
+
+Backticks C<``> (see L<perlop/"I/O Operators">) with the command which contains
+redirection or shell meta-characters;
+
+=item 4
+
+If the executable called by system()/exec()/pipe-open()/C<``> is a script
+with the "magic" C<#!> line or C<extproc> line which specifies shell;
+
+=item 5
+
+If the executable called by system()/exec()/pipe-open()/C<``> is a script
+without "magic" line, and C<$ENV{EXECSHELL}> is set to shell;
+
+=item 6
+
+If the executable called by system()/exec()/pipe-open()/C<``> is not
+found;
+
+=item 7
+
+For globbing (see L<perlfunc/glob>, L<perlop/"I/O Operators">).
+
+=back
+
+For the sake of speed for a common case, in the above algorithms
+backslashes in the command name are not considered as shell metacharacters.
+
+Perl starts scripts which begin with cookies
+C<extproc> or C<#!> directly, without an intervention of shell. Perl uses the
+same algorithm to find the executable as F<pdksh>: if the path
+on C<#!> line does not work, and contains C</>, then the executable
+is searched in F<.> and on C<PATH>. To find arguments for these scripts
+Perl uses a different algorithm than F<pdksh>: up to 3 arguments are
+recognized, and trailing whitespace is stripped.
+
+If a script
+does not contain such a cooky, then to avoid calling F<sh.exe>, Perl uses
+the same algorithm as F<pdksh>: if C<$ENV{EXECSHELL}> is set, the
+script is given as the first argument to this command, if not set, then
+C<$ENV{COMSPEC} /c> is used (or a hardwired guess if C<$ENV{COMSPEC}> is
+not set).
+
+If starting scripts directly, Perl will use exactly the same algorithm as for
+the search of script given by B<-S> command-line option: it will look in
+the current directory, then on components of C<$ENV{PATH}> using the
+following order of appended extensions: no extension, F<.cmd>, F<.btm>,
+F<.bat>, F<.pl>.
+
+Note that Perl will start to look for scripts only if OS/2 cannot start the
+specified application, thus C<system 'blah'> will not look for a script if
+there is an executable file F<blah.exe> I<anywhere> on C<PATH>.
+
+Note also that executable files on OS/2 can have an arbitrary extension,
+but F<.exe> will be automatically appended if no dot is present in the name.
+The workaround as as simple as that: since F<blah.> and F<blah> denote the
+same file, to start an executable residing in file F<n:/bin/blah> (no
+extension) give an argument C<n:/bin/blah.> to system().
+
+The last note is that currently it is not straightforward to start PM
+programs from VIO (=text-mode) Perl process and visa versa. Either ensure
+that shell will be used, as in C<system 'cmd /c epm'>, or start it using
+optional arguments to system() documented in C<OS2::Process> module. This
+is considered a bug and should be fixed soon.
+
=head1 Frequently asked questions
). You need the latest version of F<pdksh> installed as F<sh.exe>.
+Check that you have B<BSD> libraries and headers installed, and -
+optionally - Berkeley DB headers and libraries, and crypt.
+
Possible locations to get this from are
ftp://hobbes.nmsu.edu/os2/unix/
ftp://ftp.math.ohio-state.edu/pub/users/ilya/os2/db_mt.zip
+To make C<-p> filetest work, one may also need to apply the following patch
+to EMX headers:
+
+ --- /emx/include/sys/stat.h.orig Thu May 23 13:48:16 1996
+ +++ /emx/include/sys/stat.h Sun Jul 12 14:11:32 1998
+ @@ -53,7 +53,7 @@ struct stat
+ #endif
+
+ #if !defined (S_IFMT)
+ -#define S_IFMT 0160000 /* Mask for file type */
+ +#define S_IFMT 0170000 /* Mask for file type */
+ #define S_IFIFO 0010000 /* Pipe */
+ #define S_IFCHR 0020000 /* Character device */
+ #define S_IFDIR 0040000 /* Directory */
+
+
=head2 Hand-editing
You may look into the file F<./hints/os2.sh> and correct anything
=head2 Testing
+If you haven't yet moved perl.dll onto LIBPATH, do it now (alternatively, if
+you have a previous perl installation you'd rather not disrupt until this one
+is installed, copy perl.dll to the t directory).
+
Now run
make test
Some tests (4..6) should fail. Some perl invocations should end in a
-segfault (system error C<SYS3175>). To get finer error reports,
+segfault (system error C<SYS3175>). To get finer error reports, call
- cd t
- perl harness
+ perl t/harness
The report you get may look like
op/stat.t 56 5 8.93% 3-4, 20, 35, 39
Failed 4/140 test scripts, 97.14% okay. 27/2937 subtests failed, 99.08% okay.
-Note that using `make test' target two more tests may fail: C<op/exec:1>
+Note that using C<make test> target two more tests may fail: C<op/exec:1>
because of (mis)feature of pdksh, and C<lib/posix:15>, which checks
that the buffers are not flushed on C<_exit> (this is a bug in the test
which assumes that tty output is buffered).
=over 4
-=item A lot of `bad free'
+=item A lot of C<bad free>
in databases related to Berkeley DB. This is a confirmed bug of
DB. You may disable this warnings, see L<"PERL_BADFREE">.
=back
-A lot of `bad free'... in databases, bug in DB confirmed on other
+A lot of C<bad free>... in databases, bug in DB confirmed on other
platforms. You may disable it by setting PERL_BADFREE environment variable
to 1.
=head2 Installing the built perl
+If you haven't yet moved perl.dll onto LIBPATH, do it now.
+
Run
make install
You do not have MT-safe F<db.lib>. See L<Prerequisites>.
-=head2 Problems with tr
+=head2 Problems with tr or sed
-reported with very old version of tr.
+reported with very old version of tr and sed.
=head2 Some problem (forget which ;-)
=head2 Additional modules:
-L<OS2::Process>, L<OS2::REXX>, L<OS2::PrfDB>, L<OS2::ExtAttr>. This
-modules provide access to additional numeric argument for C<system>,
+L<OS2::Process>, L<OS2::REXX>, L<OS2::PrfDB>, L<OS2::ExtAttr>. These
+modules provide access to additional numeric argument for C<system>
+and to the list of the running processes,
to DLLs having functions with REXX signature and to REXX runtime, to
OS/2 databases in the F<.INI> format, and to Extended Attributes.
=item
-Since L<flock(3)> is present in EMX, but is not functional, the same is
-true for perl. Here is the list of things which may be "broken" on
+Since L<flock(3)> is present in EMX, but is not functional, it is
+emulated by perl. To disable the emulations, set environment variable
+C<USE_PERL_FLOCK=0>.
+
+=item
+
+Here is the list of things which may be "broken" on
EMX (from EMX docs):
=over
=item *
-L<flock(3)> is not yet implemented (dummy function).
+L<flock(3)> is not yet implemented (dummy function). (Perl has a workaround.)
=item *
C<os2_stat> special-cases F</dev/tty> and F</dev/con>.
+=item C<flock>
+
+Since L<flock(3)> is present in EMX, but is not functional, it is
+emulated by perl. To disable the emulations, set environment variable
+C<USE_PERL_FLOCK=0>.
+
=back
=head1 Perl flavors
Specific for EMX port. Gives the directory part of the location for
F<sh.exe>.
+=head2 C<USE_PERL_FLOCK>
+
+Specific for EMX port. Since L<flock(3)> is present in EMX, but is not
+functional, it is emulated by perl. To disable the emulations, set
+environment variable C<USE_PERL_FLOCK=0>.
+
=head2 C<TMP> or C<TEMP>
Specific for EMX port. Used as storage place for temporary files, most
=head2 Threading
As of release 5.003_01 perl is linked to multithreaded CRT
-DLL. Perl itself is not multithread-safe, as is not perl
+DLL. If perl itself is not compiled multithread-enabled, so will not be perl
malloc(). However, extensions may use multiple thread on their own
risk.
whatever is the override, see L<"PERL_SH_DIR">.
Thus means that you need to get some copy of a F<sh.exe> as well (I
-use one from pdksh). The drive F: above is set up automatically during
+use one from pdksh). The drive F<F:> above is set up automatically during
the build to a correct value on the builder machine, but is
overridable at runtime,
I will include it into distribution. I have no need for such a module, so
cannot test it.
+For the details of the current situation with calling external programs,
+see L<Starting OS/2 (and DOS) programs under Perl>.
+
+=over
+
+=item
+
+External scripts may be called by name. Perl will try the same extensions
+as when processing B<-S> command-line switch.
+
+=back
+
=head2 Memory allocation
Perl uses its own malloc() under OS/2 - interpreters are usually malloc-bound
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