Notes

Outline

"Mark Bixby csy r&d..." Mark Bixby csy r&d lab april 4, 2002 perl programming on mpe/ix

introduction and history Practical Extraction and Report Language Pathologically Eclectic Rubbish Lister? the Swiss Army chainsaw of scripting languages optimized for text processing combines the best of C, sh, awk, and sed released in 1987 by Larry Wall initially ported to MPE by Mark Klein re-ported by Mark Bixby in 1997 with periodic updates since then "There's more than one way to do it!"

current status Perl release v5.6.1 available for MPE from jazz.external.hp.com Perl is not currently supported by HP, but if your use of Perl uncovers any underlying MPE or POSIX bugs, then we certainly want to hear from you! the best way to get assistance with Perl on MPE is to post your questions to HP3000-L official HP support for Perl on MPE is not currently planned

migrating from perl/ix to other platforms Perl originated on Unix and has been ported to virtually all flavors of Unix Perl is also available for Mac and Windows! Perl/iX is 105% compatible with perl on Unix where certain perl functionality works better than on MPE: terminal I/O sockets If you use Perl/iX for creating new business logic on MPE, it will be readily portable to other platforms

installation download from http://jazz.external.hp.com/src/hp_freeware/perl/ edit and run the INSTALL script creates a PERL account does not use Priv-Mode capability /PERL/PUB/perl is the interpreter start scripts with #!/PERL/PUB/perl don't start scripts with #!/PERL/PUB/PERL

how to execute the interpreter From the shell: /PERL/PUB/perl [optional parameters] As a shell script: #!/PERL/PUB/perl [optional parameters] From the CI: :XEQ SH.HPBIN.SYS '-c "/PERL/PUB/perl [optional parameters]"' -c - check syntax without doing execution -d - run the Perl debugger -e - specify one line of script (like sed) -v - print minimal version information -V - print verbose version information -w - prints VERY useful syntax and runtime warnings; everybody should make a habit of testing their scripts with this!

variable names scalar values $days # the simple scalar value "days" $days[28] # the 29th element of array @days $days{'Feb'} # the 'Feb' value from hash %days $#days # the last index of array @days entire arrays or array slices (aka lists) @days # ($days[0], $days[1],... $days[n]) @days[3,4,5] # same as @days[3..5] @days{'a','c'} # same as ($days{'a'},$days{'c'}) entire hashes %days # (key1, val1, key2, val2 ...)

value constructors scalar values $abc = 12345; $abc = 12345.67; $abc = 0xffff; # hexadecimal $abc = 0377; # octal $abc = 'a simple string'; $abc = "a string with a newline\n"; list values @abc = ("cat", "dog", $def); ($dev, $ino, undef, undef, $uid, $gid) = stat($file); hash values $abc{'December'} = 12; $month = $abc{'December'};

scalar vs. list context the context of some operations will determine the type of the data returned scalar list assignment to a scalar variable will evaluate the righthand side in a scalar context $onerecord = <STDIN> assignment to a list variable will evaluate the righthand side in a list context @entirefile = <STDIN> context-based behavior is always documented

simple statements terminated with a semicolon may be followed by one optional modifier if EXPR unless EXPR while EXPR until EXPR foreach EXPR $os = 'mpe'; $os = 'mpe' if $model == 3000;

compound statements a block is a sequence of statements delimited by curly brackets (braces) that defines a scope compound statements that control flow: if (EXPR) BLOCK if (EXPR) BLOCK else BLOCK if (EXPR) BLOCK elsif (EXPR) BLOCK ... else BLOCK LABEL while (EXPR) BLOCK LABEL while (EXPR) BLOCK continue BLOCK LABEL for (EXPR; EXPR; EXPR) BLOCK LABEL foreach VAR (LIST) BLOCK loop control via next, last, and redo if ($model == 3000) { $os = 'mpe' };

subroutines sub max {   my $max = shift(@_);   foreach $foo (@_) {     $max = $foo if $max < $foo; }   return $max; } $bestday = max($mon,$tue,$wed,$thu,$fri); parameters passed via @_ array @_[0] = parm1, @_[1] = parm2, etc @_ is an alias (i.e. call by reference) private variables declared with my return or the value of the last expression is the functional return value

arithmetic operators addition: + subtraction: - multiplication: * division: / modulus: % exponentiation: ** auto-increment and -decrement: ++ -- ++$a - increments $a, returns new value $a++ - returns current value, then increments $a

assignment operators works like C $a += 2; is equivalent to $a = $a + 2; **=   +=   *=   &=   <<=   &&=   -=   /= |=    >>=  ||=  .=   %=    ^=    x=

relational operators numeric comparisons: <  >  <= >= == != <=> <=> returns -1, 0, or 1 depending on whether the left argument is numerically less than, equal to, or greater than the right argument string comparsions: lt gt le ge eq ne cmp cmp returns -1, 0, or 1 depending on whether the left argument is stringwise less than, equal to, or greater than the right argument

bitwise operators shift left: << shift right: >> AND: & OR: | XOR: ^ negation: ~

i/o and file handles open files are identified via file handles uppercase handle names by convention predefined file handles: STDIN, STDOUT, STDERR <FILEHANDLE> in a scalar context reads the next record from the file <FILEHANDLE> in a list context reads ALL of the remaining records from the file filenames must be specified using POSIX HFS syntax instead of MPE syntax

opening files with open() open(HANDLE, "/path/to/file") # open for reading open(HANDLE, "< /path/to/file") # open for reading open(HANDLE, "> /path/to/file") # open for writing open(HANDLE, ">> /path/to/file") # open for appending open(HANDLE, "| shell command") # open pipe for writing open(HANDLE, "shell command |") # open pipe for reading Be very careful when passing user data to open() as a file name!  Hackers know to try using the special metacharacters listed above.

a file i/o example #!/PERL/PUB/perl open(HPSW, "/SYS/PUB/HPSWINFO"); # open for input $one = <HPSW>; # read first line $two = <HPSW>; # read second line $three = <HPSW>; # read third line @therest = <HPSW>; # read all remaining lines close(HPSW); # close the file open(PATCHES, "> /tmp/MPE.patches"); # open for output foreach $line (@therest) { # access each array line   print PATCHES $line if $line =~ /^MPE/; # print if match } close(PATCHES); # close the file

regular expressions a vast superset beyond standard Unix regexps a ? modifier to make patterns non-greedy zero-width lookahead and lookbehind assertions conditional expressions extra character class matches: \w - match a "word" character (alphanumeric, "_") \W - match a non-word character \s - match a whitespace character \S - match a non-whitespace character \d - match a digit \D - match a non-digit http://www.perl.com/pub/doc/manual/html/pod/perlre.html

using regular expressions $showme=`callci showme`; if ($showme =~ /RELEASE: ([A-Z]\.(\d)(\d)\.\d\d)/) {   $release = $1;  # the matching V.UU.FF   $mpe = "$2.$3"; # the matching U and U (i.e. 7.0) } $showme =~ s/LDev/Logical Device/gi; # global substitution $n contains the value of the n-th matching parenthesized regexp the g suffix causes a global substitution the i suffix causes case-insensitive matching

predefined variables - a partial list $| or $OUTPUT_AUTOFLUSH By default, all Perl output is buffered (0).  To enable automatic flushing, set this variable to 1.  Needed when doing MPE I/O which is usually unbuffered. $$ or $PID POSIX PID of the current process $^O or $OSNAME operating system name (mpeix) @ARGV script parameters if any %ENV or $ENV{varname} accesses the POSIX environment variables

built-in functions - a partial list Functions for SCALARs or strings chomp, chop, chr, crypt, hex, index, lc, lcfirst, length, oct, ord, pack, q/STRING/, qq/STRING/, reverse, rindex, sprintf, substr, tr///, uc, ucfirst, y/// Regular expressions and pattern matching m//, pos, quotemeta, s///, split, study, qr// Numeric functions abs, atan2, cos, exp, hex, int, log, oct, rand, sin, sqrt, srand Functions for real @ARRAYs pop, push, shift, splice, unshift Functions for list data grep, join, map, qw/STRING/, reverse, sort, unpack Functions for real %HASHes delete, each, exists, keys, values Functions for fixed length data or records pack, read, syscall, sysread, syswrite, unpack, vec

built-in functions (cont.) Input and output functions binmode, close, closedir, dbmclose, dbmopen, die, eof, fileno, flock, format, getc, print, printf, read, readdir, rewinddir, seek, seekdir, select, syscall, sysread, sysseek, syswrite, tell, telldir, truncate, warn, write Functions for filehandles, files, or directories -X, chdir, chmod, chown, chroot, fcntl, glob, ioctl, link, lstat, mkdir, open, opendir, readlink, rename, rmdir, stat, symlink, umask, unlink, utime Keywords related to the control flow of your perl program caller, continue, die, do, dump, eval, exit, goto, last, next, redo, return, sub Keywords related to perl modules do, import, no, package, require, use Functions for processes and process groups alarm, exec, fork, getpgrp, getppid, getpriority, kill, pipe, qx/STRING/, setpgrp, setpriority, sleep, system, times, wait, waitpid Time-related functions gmtime, localtime, time, times

built-in functions (cont.) Keywords related to classes and object-orientedness bless, dbmclose, dbmopen, package, ref, tie, tied, untie, use Low-level socket functions accept, bind, connect, getpeername, getsockname, getsockopt, listen, recv, send, setsockopt, shutdown, socket, socketpair System V interprocess communication functions msgctl, msgget, msgrcv, msgsnd, semctl, semget, semop, shmctl, shmget, shmread, shmwrite Fetching user and group info endgrent, endhostent, endnetent, endpwent, getgrent, getgrgid, getgrnam, getlogin, getpwent, getpwnam, getpwuid, setgrent, setpwent Fetching network info endprotoent, endservent, gethostbyaddr, gethostbyname, gethostent, getnetbyaddr, getnetbyname, getnetent, getprotobyname, getprotobynumber, getprotoent, getservbyname, getservbyport, getservent, sethostent, setnetent, setprotoent, setservent

object oriented programming an object consists of: attributes (data) methods (functions to manipulate the attributes) many CPAN modules are object-oriented for more info: http://www.perl.com/pub/2000/12/begperl5.html http://www.perldoc.com/perl5.6.1/pod/perltoot.html

object definitions example - Foo.pm package Foo; sub new { # method subroutine     my ($class_name) = @_;     my ($self) = {}; # create an empty hash to store attributes     bless ($self, $class_name); # make it an object     $self->{'_created'} = 1;     return $self; } sub put { # method subroutine     my ($self, $data) = @_;     $self->{_bar} = $data; # store data in the _bar attribute } sub get { # method subroutine     my ($self) = @_;     return $self->{_bar}; # return data from the _bar attribute } 1; # return code for use statement

object usage example #!/PERL/PUB/perl use Foo; # refers to Foo.pm file $it = new Foo(); # create a new object $it->put('hello world'); # use the put method printf "The value is %s\n",$it->get(); # use the get method

interprocess communications POSIX signals between related processes named pipes between unrelated processes create named pipes with POSIX mkfifo command unnamed pipes to child processes create using Perl open() function with "|" Internet-domain TCP and UDP sockets Unix-domain stream sockets SysV IPC - shared memory, semaphores, messages

sockets - a procedural client example #!/PERL/PUB/perl -w use Socket; $proto = getprotobyname('tcp'); # get protocol number $ipaddr = inet_aton('localhost'); # get the host's IP address $port = getservbyname('daytime', 'tcp'); # get port number $address = sockaddr_in($port, $ipaddr);  # create addr struct socket(SOCK, PF_INET, SOCK_STREAM, $proto); # create the socket connect(SOCK, $address); # connect to remote host $timestamp = <SOCK>; # read a line of data print "$timestamp\n"; # print the results close(SOCK); # close the socket

sockets - an object-oriented client example #!/PERL/PUB/perl -w use IO::Socket; # create the socket and connect to the host $remote = IO::Socket::INET->new(     Proto = 'tcp',     PeerAddr = 'localhost',     PeerPort = 'daytime'); $timestamp = <$remote>; # read a line of data from the socket print "$timestamp\n"; # print the results close($remote); # close the socket

web server cgi - a simple example use CGI qw(:standard); print header; print start_html('A Simple Example'),     h1('A Simple Example'),     start_form,     "What's your name? ",textfield('name'),     p,     "What's the combination?",     p,     checkbox_group(-name=>'words',                    -values=>['eenie','meenie','minie','moe'],                    -defaults=>['eenie','minie']),     p,     "What's your favorite color? ",     popup_menu(-name=>'color',                -values=>['red','green','blue','chartreuse']),     p,     submit,     end_form,     hr;

web server cgi - a simple example (cont.) if (param()) {     print         "Your name is ",em(param('name')),         p,         "The keywords are: ",em(join(", ",param('words'))),         p,         "Your favorite color is ",em(param('color')),         hr; } print end_html; http://stein.cshl.org/WWW/software/CGI/ for more information

mpe as a web client it's now possible to write MPE applications that look like web browsers perform simple HTTP GET requests, or even complicated HTTP POST requests to fill out remote web forms #!/PERL/PUB/perl use LWP::Simple; # read the web page contents into the scalar variable $webpage $webpage = get('http://www.bixby.org/mark/perlix.html'); See http://www.linpro.no/lwp/ for more information

debugging invoke the debugger by starting Perl with the -d parameter #!/PERL/PUB/perl -d examine or modify variables single-step execution set breakpoints list source code set actions to be done before a line is executed a 53 print "DB FOUND $foo\n" debugger terminal I/O may act a bit strangely on MPE

perl extensions binary code residing in an external NMXL loaded at run time a thin layer of C that allows the Perl interpreter to call compiled code written in other languages several extension libraries come bundled with Perl (sockets, POSIX, etc) a decent tutorial is available - the examples even work on MPE! http://www.perldoc.com/perl5.6.1/pod/perlxstut.html this is how you would do it to add support for intrinsics

comprehensive perl archive network (cpan) http://www.cpan.org/ a vast collection of free Perl modules over 3000 modules of cool stuff mirrored at more than 175 sites around the world typical installation process for a CPAN module: perl Makefile.PL make make test make install

integration with mpe for access to MPE commands: system("callci mpe_command") `callci mpe_command` integration with Apache via mod_perl available from  http://www.bixby.org/mark/apacheix.html (unsupported freeware) TurboIMAGE intrinsic functionality available from http://www.cpan.org/modules/by-authors/Ted_Ashton/ CI command, JCW, variable, and file intrinsic functionality available from http://invent3k.external.hp.com/~MGR.HIRSCH/ want to increase Perl's integration with MPE? a great opportunity for somebody to write additional MPE-specific Perl extension libraries

perl resources http://www.perl.com/ - the starting point for all things Perl http://perl.oreilly.com/news/success_stories.html - how Perl is being used in real-life situations http://www.perl.com/pub/2000/10/begperl1.html - Beginner's Introduction to Perl http://perl.apache.org/ - The Apache/Perl Integration Project http://jazz.external.hp.com/src/hp_freeware/perl - for the latest info about Perl on MPE Usenet newsgroups comp.lang.perl.*

join the hp3000-L community! Available as a mailing list and as the Usenet newsgroup comp.sys.hp.mpe In-depth discussions of all things HP e3000 Talk with other people using Perl on MPE seek advice, exchange tips & techniques Keep up with the latest HP e3000 news Interact with CSY http://jazz.external.hp.com/papers/hp3000-info.html