perlvms.1

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.IX Header "PERL_VMS_EXCEPTION_DEBUG"
The \s-1PERL_VMS_EXCEPTION_DEBUG\s0 being defined as \*(L"\s-1ENABLE\s0\*(R" will cause the \s-1VMS\s0
debugger to be invoked if a fatal exception that is not otherwise
handled is raised.  The purpose of this is to allow debugging of
internal Perl problems that would cause such a condition.
.PP
This allows the programmer to look at the execution stack and variables to
find out the cause of the exception.  As the debugger is being invoked as
the Perl interpreter is about to do a fatal exit, continuing the execution
in debug mode is usally not practical.
.PP
Starting Perl in the \s-1VMS\s0 debugger may change the program execution
profile in a way that such problems are not reproduced.
.PP
The \f(CW\*(C`kill\*(C'\fR function can be used to test this functionality from within
a program.
.PP
In typical \s-1VMS\s0 style, only the first letter of the value of this logical
name is actually checked in a case insensitive mode, and it is considered
enabled if it is the value \*(L"T\*(R",\*(L"1\*(R" or \*(L"E\*(R".
.PP
This logical name must be defined before Perl is started.
.SH "Command line"
.IX Header "Command line"
.Sh "I/O redirection and backgrounding"
.IX Subsection "I/O redirection and backgrounding"
Perl for \s-1VMS\s0 supports redirection of input and output on the 
command line, using a subset of Bourne shell syntax:
.IP "\(bu" 4
\&\f(CW\*(C`<file\*(C'\fR reads stdin from \f(CW\*(C`file\*(C'\fR,
.IP "\(bu" 4
\&\f(CW\*(C`>file\*(C'\fR writes stdout to \f(CW\*(C`file\*(C'\fR,
.IP "\(bu" 4
\&\f(CW\*(C`>>file\*(C'\fR appends stdout to \f(CW\*(C`file\*(C'\fR,
.IP "\(bu" 4
\&\f(CW\*(C`2>file\*(C'\fR writes stderr to \f(CW\*(C`file\*(C'\fR,
.IP "\(bu" 4
\&\f(CW\*(C`2>>file\*(C'\fR appends stderr to \f(CW\*(C`file\*(C'\fR, and
.IP "\(bu" 4
\&\f(CW\*(C`2>&1\*(C'\fR redirects stderr to stdout.
.PP
In addition, output may be piped to a subprocess, using the  
character '|'.  Anything after this character on the command 
line is passed to a subprocess for execution; the subprocess 
takes the output of Perl as its input.
.PP
Finally, if the command line ends with '&', the entire 
command is run in the background as an asynchronous 
subprocess.
.Sh "Command line switches"
.IX Subsection "Command line switches"
The following command line switches behave differently under
\&\s-1VMS\s0 than described in perlrun.  Note also that in order
to pass uppercase switches to Perl, you need to enclose
them in double-quotes on the command line, since the \s-1CRTL\s0
downcases all unquoted strings.
.PP
On newer 64 bit versions of OpenVMS, a process setting now
controls if the quoting is needed to preserve the case of
command line arguments.
.IP "\-i" 4
.IX Item "-i"
If the \f(CW\*(C`\-i\*(C'\fR switch is present but no extension for a backup
copy is given, then inplace editing creates a new version of
a file; the existing copy is not deleted.  (Note that if
an extension is given, an existing file is renamed to the backup
file, as is the case under other operating systems, so it does
not remain as a previous version under the original filename.)
.IP "\-S" 4
.IX Item "-S"
If the \f(CW"\-S"\fR or \f(CW\*(C`\-"S"\*(C'\fR switch is present \fIand\fR the script
name does not contain a directory, then Perl translates the
logical name \s-1DCL$PATH\s0 as a searchlist, using each translation
as a directory in which to look for the script.  In addition,
if no file type is specified, Perl looks in each directory
for a file matching the name specified, with a blank type,
a type of \fI.pl\fR, and a type of \fI.com\fR, in that order.
.IP "\-u" 4
.IX Item "-u"
The \f(CW\*(C`\-u\*(C'\fR switch causes the \s-1VMS\s0 debugger to be invoked
after the Perl program is compiled, but before it has
run.  It does not create a core dump file.
.SH "Perl functions"
.IX Header "Perl functions"
As of the time this document was last revised, the following 
Perl functions were implemented in the \s-1VMS\s0 port of Perl 
(functions marked with * are discussed in more detail below):
.PP
.Vb 10
\&    file tests*, abs, alarm, atan, backticks*, binmode*, bless,
\&    caller, chdir, chmod, chown, chomp, chop, chr,
\&    close, closedir, cos, crypt*, defined, delete, die, do, dump*, 
\&    each, endgrent, endpwent, eof, eval, exec*, exists, exit, exp, 
\&    fileno, flock  getc, getgrent*, getgrgid*, getgrnam, getlogin, getppid,
\&    getpwent*, getpwnam*, getpwuid*, glob, gmtime*, goto,
\&    grep, hex, ioctl, import, index, int, join, keys, kill*,
\&    last, lc, lcfirst, lchown*, length, link*, local, localtime, log, lstat, m//,
\&    map, mkdir, my, next, no, oct, open, opendir, ord, pack,
\&    pipe, pop, pos, print, printf, push, q//, qq//, qw//,
\&    qx//*, quotemeta, rand, read, readdir, readlink*, redo, ref, rename,
\&    require, reset, return, reverse, rewinddir, rindex,
\&    rmdir, s///, scalar, seek, seekdir, select(internal),
\&    select (system call)*, setgrent, setpwent, shift, sin, sleep,
\&    socketpair, sort, splice, split, sprintf, sqrt, srand, stat,
\&    study, substr, symlink*, sysread, system*, syswrite, tell,
\&    telldir, tie, time, times*, tr///, uc, ucfirst, umask,
\&    undef, unlink*, unpack, untie, unshift, use, utime*,
\&    values, vec, wait, waitpid*, wantarray, warn, write, y///
.Ve
.PP
The following functions were not implemented in the \s-1VMS\s0 port, 
and calling them produces a fatal error (usually) or 
undefined behavior (rarely, we hope):
.PP
.Vb 4
\&    chroot, dbmclose, dbmopen, fork*, getpgrp, getpriority,  
\&    msgctl, msgget, msgsend, msgrcv, semctl,
\&    semget, semop, setpgrp, setpriority, shmctl, shmget,
\&    shmread, shmwrite, syscall
.Ve
.PP
The following functions are available on Perls compiled with Dec C
5.2 or greater and running \s-1VMS\s0 7.0 or greater:
.PP
.Vb 1
\&    truncate
.Ve
.PP
The following functions are available on Perls built on \s-1VMS\s0 7.2 or
greater:
.PP
.Vb 1
\&    fcntl (without locking)
.Ve
.PP
The following functions may or may not be implemented, 
depending on what type of socket support you've built into 
your copy of Perl:
.PP
.Vb 9
\&    accept, bind, connect, getpeername,
\&    gethostbyname, getnetbyname, getprotobyname,
\&    getservbyname, gethostbyaddr, getnetbyaddr,
\&    getprotobynumber, getservbyport, gethostent,
\&    getnetent, getprotoent, getservent, sethostent,
\&    setnetent, setprotoent, setservent, endhostent,
\&    endnetent, endprotoent, endservent, getsockname,
\&    getsockopt, listen, recv, select(system call)*,
\&    send, setsockopt, shutdown, socket
.Ve
.PP
The following function is available on Perls built on 64 bit OpenVMS v8.2
with hard links enabled on an \s-1ODS\-5\s0 formatted build disk.  \s-1CRTL\s0 support
is in principle available as of OpenVMS v7.3\-1, and better configuration
support could detect this.
.PP
.Vb 1
\&    link
.Ve
.PP
The following functions are available on Perls built on 64 bit OpenVMS
v8.2 and later.  \s-1CRTL\s0 support is in principle available as of OpenVMS
v7.3\-2, and better configuration support could detect this.
.PP
.Vb 2
\&   getgrgid, getgrnam, getpwnam, getpwuid,
\&   setgrent, ttyname
.Ve
.PP
The following functions are available on Perls built on 64 bit OpenVMS v8.2
and later.
.PP
.Vb 1
\&   statvfs, socketpair
.Ve
.IP "File tests" 4
.IX Item "File tests"
The tests \f(CW\*(C`\-b\*(C'\fR, \f(CW\*(C`\-B\*(C'\fR, \f(CW\*(C`\-c\*(C'\fR, \f(CW\*(C`\-C\*(C'\fR, \f(CW\*(C`\-d\*(C'\fR, \f(CW\*(C`\-e\*(C'\fR, \f(CW\*(C`\-f\*(C'\fR,
\&\f(CW\*(C`\-o\*(C'\fR, \f(CW\*(C`\-M\*(C'\fR, \f(CW\*(C`\-s\*(C'\fR, \f(CW\*(C`\-S\*(C'\fR, \f(CW\*(C`\-t\*(C'\fR, \f(CW\*(C`\-T\*(C'\fR, and \f(CW\*(C`\-z\*(C'\fR work as
advertised.  The return values for \f(CW\*(C`\-r\*(C'\fR, \f(CW\*(C`\-w\*(C'\fR, and \f(CW\*(C`\-x\*(C'\fR
tell you whether you can actually access the file; this may
not reflect the UIC-based file protections.  Since real and
effective \s-1UIC\s0 don't differ under \s-1VMS\s0, \f(CW\*(C`\-O\*(C'\fR, \f(CW\*(C`\-R\*(C'\fR, \f(CW\*(C`\-W\*(C'\fR,
and \f(CW\*(C`\-X\*(C'\fR are equivalent to \f(CW\*(C`\-o\*(C'\fR, \f(CW\*(C`\-r\*(C'\fR, \f(CW\*(C`\-w\*(C'\fR, and \f(CW\*(C`\-x\*(C'\fR.
Similarly, several other tests, including \f(CW\*(C`\-A\*(C'\fR, \f(CW\*(C`\-g\*(C'\fR, \f(CW\*(C`\-k\*(C'\fR,
\&\f(CW\*(C`\-l\*(C'\fR, \f(CW\*(C`\-p\*(C'\fR, and \f(CW\*(C`\-u\*(C'\fR, aren't particularly meaningful under
\&\s-1VMS\s0, and the values returned by these tests reflect whatever
your \s-1CRTL\s0 \f(CW\*(C`stat()\*(C'\fR routine does to the equivalent bits in the
st_mode field.  Finally, \f(CW\*(C`\-d\*(C'\fR returns true if passed a device
specification without an explicit directory (e.g. \f(CW\*(C`DUA1:\*(C'\fR), as
well as if passed a directory.
.Sp
There are \s-1DECC\s0 feature logical names \s-1AND\s0 \s-1ODS\-5\s0 volume attributes that
also control what values are returned for the date fields.
.Sp
Note: Some sites have reported problems when using the file-access
tests (\f(CW\*(C`\-r\*(C'\fR, \f(CW\*(C`\-w\*(C'\fR, and \f(CW\*(C`\-x\*(C'\fR) on files accessed via \s-1DEC\s0's \s-1DFS\s0.
Specifically, since \s-1DFS\s0 does not currently provide access to the
extended file header of files on remote volumes, attempts to
examine the \s-1ACL\s0 fail, and the file tests will return false,
with \f(CW$!\fR indicating that the file does not exist.  You can
use \f(CW\*(C`stat\*(C'\fR on these files, since that checks UIC-based protection
only, and then manually check the appropriate bits, as defined by
your C compiler's \fIstat.h\fR, in the mode value it returns, if you
need an approximation of the file's protections.
.IP "backticks" 4
.IX Item "backticks"
Backticks create a subprocess, and pass the enclosed string
to it for execution as a \s-1DCL\s0 command.  Since the subprocess is
created directly via \f(CW\*(C`lib$spawn()\*(C'\fR, any valid \s-1DCL\s0 command string
may be specified.
.IP "binmode \s-1FILEHANDLE\s0" 4
.IX Item "binmode FILEHANDLE"
The \f(CW\*(C`binmode\*(C'\fR operator will attempt to insure that no translation
of carriage control occurs on input from or output to this filehandle.
Since this involves reopening the file and then restoring its
file position indicator, if this function returns \s-1FALSE\s0, the
underlying filehandle may no longer point to an open file, or may
point to a different position in the file than before \f(CW\*(C`binmode\*(C'\fR
was called.
.Sp
Note that \f(CW\*(C`binmode\*(C'\fR is generally not necessary when using normal
filehandles; it is provided so that you can control I/O to existing
record-structured files when necessary.  You can also use the
\&\f(CW\*(C`vmsfopen\*(C'\fR function in the VMS::Stdio extension to gain finer
control of I/O to files and devices with different record structures.
.IP "crypt \s-1PLAINTEXT\s0, \s-1USER\s0" 4
.IX Item "crypt PLAINTEXT, USER"
The \f(CW\*(C`crypt\*(C'\fR operator uses the \f(CW\*(C`sys$hash_password\*(C'\fR system
service to generate the hashed representation of \s-1PLAINTEXT\s0.
If \s-1USER\s0 is a valid username, the algorithm and salt values
are taken from that user's \s-1UAF\s0 record.  If it is not, then
the preferred algorithm and a salt of 0 are used.  The
quadword encrypted value is returned as an 8\-character string.
.Sp
The value returned by \f(CW\*(C`crypt\*(C'\fR may be compared against
the encrypted password from the \s-1UAF\s0 returned by the \f(CW\*(C`getpw*\*(C'\fR
functions, in order to authenticate users.  If you're
going to do this, remember that the encrypted password in
the \s-1UAF\s0 was generated using uppercase username and
password strings; you'll have to upcase the arguments to
\&\f(CW\*(C`crypt\*(C'\fR to insure that you'll get the proper value:
.Sp
.Vb 9
\&    sub validate_passwd {
\&        my($user,$passwd) = @_;
\&        my($pwdhash);
\&        if ( !($pwdhash = (getpwnam($user))[1]) ||
\&               $pwdhash ne crypt("\eU$passwd","\eU$name") ) {
\&            intruder_alert($name);
\&        }
\&        return 1;
\&    }
.Ve
.IP "die" 4
.IX Item "die"
\&\f(CW\*(C`die\*(C'\fR will force the native \s-1VMS\s0 exit status to be an \s-1SS$_ABORT\s0 code
if neither of the $! or $? status values are ones that would cause
the native status to be interpreted as being what \s-1VMS\s0 classifies as
\&\s-1SEVERE_ERROR\s0 severity for \s-1DCL\s0 error handling.
.Sp
When the future \s-1POSIX_EXIT\s0 mode is active, \f(CW\*(C`die\*(C'\fR, the native \s-1VMS\s0 exit