FW: Perl Reporting by Anthony Lawrence

I often forget about Perl's reporting formats, and I suspect that a lot of people do - we're so used to Perl as a programming language that we forget it's original namesake: Practical Extraction and Report Language. Reporting was a big part of Perl's beginnings, but it's hardly ever mentioned today.

In fact, it's been so long since I have used any of these features that I had to drag out my big Camel Book to review the whole subject - I had forgotten everything. Fortunately, it's not hard, and using these capabilities can make output much easier: you don't have to keep track of lines printed so that you can generate headers on new pages or print page numbers: Perl does that for you. You can justify and center, easily handle variable width data and more. Perl Report Formats make all this easy.

Here's an example using a format suggested in the Camel book (or online at Perl Formats)

:

#!/usr/bin/perl

# a report on the /etc/passwd file

format STDOUT_TOP =

                        Passwd File

Name                Login    Office   Uid   Gid Home

------------------------------------------------------------------

.

format STDOUT =

@<<<<<<<<<<<<<<<<<< @||||||| @<<<<<<@>>>> @>>>> @<<<<<<<<<<<<<<<<<

$name,              $login,  $office,$uid,$gid, $home

.

$= = 20;

# sets 20 lines per page

while (<>) {

( $name, $login,  $office,$uid,$gid, $home) =split /:/;

next if not $login;

write;

}

On my Mac, running that program with /etc/passwd as its argument produces this:

                        Passwd File

Name                Login    Office   Uid   Gid Home

------------------------------------------------------------------

nobody                 *     -2        -2 Unpri /var/empty

root                   *     0          0 Syste /var/root

daemon                 *     1          1 Syste /var/root

_uucp                  *     4          4 Unix  /var/spool/uucp

_lp                    *     26        26 Print /var/spool/cups

_postfix               *     27        27 Postf /var/spool/postfix

_mcxalr                *     54        54 MCX A /var/empty

_pcastagent            *     55        55 Podca /var/pcast/agent

_pcastserver           *     56        56 Podca /var/pcast/server

_serialnumberd         *     58        58 Seria /var/empty

_devdocs               *     59        59 Devel /var/empty

_sandbox               *     60        60 Seatb /var/empty

_mdnsresponder         *     65        65 mDNSR /var/empty

_ard                   *     67        67 Apple /var/empty

_www                   *     70        70 World /Library/WebServer

_eppc                  *     71        71 Apple /var/empty

_cvs                   *     72        72 CVS S /var/empty

_svn                   *     73        73 SVN S /var/empty

_mysql                 *     74        74 MySQL /var/empty

_sshd                  *     75        75 sshd  /var/empty

_qtss                  *     76        76 Quick /var/empty

_cyrus                 *     77         6 Cyrus /var/imap

_mailman               *     78        78 Mailm /var/empty

_appserver             *     79        79 Appli /var/empty

_clamav                *     82        82 ClamA /var/virusmails

_amavisd               *     83        83 AMaVi /var/virusmails

_jabber                *     84        84 Jabbe /var/empty

_xgridcontroller       *     85        85 Xgrid /var/xgrid/control

_xgridagent            *     86        86 Xgrid /var/xgrid/agent

_appowner              *     87        87 Appli /var/empty

_windowserver          *     88        88 Windo /var/empty

_spotlight             *     89        89 Spotl /var/empty

_tokend                *     91        91 Token /var/empty

_securityagent         *     92        92 Secur /var/empty

_calendar              *     93        93 Calen /var/empty

_teamsserver           *     94        94 Teams /var/teamsserver

_update_sharing        *     95        -2 Updat /var/empty

^L                      Passwd File

Name                Login    Office   Uid   Gid Home

------------------------------------------------------------------

_installer             *     96        -2 Insta /var/empty

_atsserver             *     97        97 ATS S /var/empty

_unknown               *     99        99 Unkno /var/empty

Ever had to handle variable length data in a report? That can be annoying, can't it? Let's say we have this text file:

02/04/2008:No changes

02/08/2008:Maintenance

02/16/2008:Major problems.  Disk crash, all work lost

02/17/2008:Starting over

02/19/2008:This is just too much work.  The project is not worth the trouble. I quit.

02/25/2008:Wow! Big raise.  Guess I don't quit.

Here's a little Perl script that eats that up:

#!/usr/bin/perl

format STDOUT =

Date              Action

@<<<<<<<<         ^<<<<<<<<<<<<<<<<<<<<

$date             $action

~                 ^<<<<<<<<<<<<<<<<<<<<

                  $action

~                 ^<<<<<<<<<<<<<<<<<...

                  $action

.

while (<>) {

($date,$action)=split /:/;

write;

}

If we run that against our data file, we'll get:

02/04/200         No changes

02/08/200         Maintenance

02/16/200         Major problems.  Disk

                  crash, all work lost

02/17/200         Starting over

02/19/200         This is just too much

                  work.  The project is

                  not worth the...

02/25/200         Wow! Big raise.

                  Guess I don't quit.

There's a lot more to this, I just wanted to give you a taste here. You can read the docs and play with it yourself but can probably easily see how much time and trouble this could save you.