Here we go again...

Posting this from a disc-less host, using a KNOPPIX V6.0.1 LiveCD downloaded to the Vista host using BitTorrent / BitComet.

This KNOPPIX disc divined the correct network configuration from the USR5430 Ethernet / WiFi bridge, which is configured as part of an AdHoc wireless (802.11) LAN which has an Internet backhaul (configured using ICS) over a Cricket CDMA USB BroadBand modem on the Vista box.

The KNOPPIX network configuration routine psychically determined all that and configured it without having to ask me any stupid questions. That, all by itself, is freaking amazing. Contrast it, for instance, with DamnSmallLinux (DSL) [v?] which I just argued with all weekend about the identical configuration. The DSL solution required adding a eth0:1 interface as root to begin with – it got worse from there. …

So it just booted up and ran without question, so far pretty much everything working, it appears.

Notable Factoids

• no spkrs on this box, so not sure about sound
• spell checker in Iceweasel is set for German
• Iceweasel is the default browser
• Iceweasel comes with the NoScript plugin already installed (!!!)
• a /slick/ new [to me] desktop environment called ‘Lightweight X11 Desktop Environment’ (LXDE) - really nice

Oddities

Is it true that USB devices only boot if they are formated FAT/32? Some weirdness going on there. If TRUE, I could put my PortableApps and my KNOPPIX on the same 4G USB stick? Maybe?

Glitches

For some reason, the 2nd & 3rd times I tried to boot this CD on this box, it hung during the X11 initialization - I believe(d) that some BIOS changes I made may have affected this, so the current settings changed are:

• Legacy USB support: enabled
• Startup Diagnostics screen: disabled

These settings may not matter, or may be specific to this system. They are recorded here so I can refer to them later, if necessary ;)

The hanging of the X11 startup is critical, since the system will shut itself down when X11 exits, and I was unable to find a way to interrupt the shutdown from the console during the time the X server was running. This means that if X hangs on this CD, the system shuts down after a short timeout.

Out of 4 boot-up attempts, the two that have worked (first and fourth) were both simple "put the CD in and hard boot w/o going to setup or boot-device select menu" sequences.

Video Resolution Bug

The screen resolution only seems to go up to 800x600. This has to be an incorrectly selected video device driver, since this same video card will go up to 1600x1200 and has done so in the past.

ASCII 0x07 - The BEL Character

The Visible bell mini-Howto describes the measures necessary to disable audio processing of the ASCII system bell (0x07 – BEL) character as a console "beep" in various shells and applications, including Bash and Emacs. under Linux.

MySQL script execution

The following is text copied from the mysql(3) manual page:

You can execute SQL statements in a script file (batch file) like this:

   shell> mysql db_name < script.sql > output.tab

The MySQL version 5.x and greater also provide a mysqldump which has an XML output switch. This causes mysqldump to output XML on stdout such that the mysqldump output can be used directly in an XML document output stream.

Emacs mixed-mode PHP sources

Caveat: For these ideas to work, you might [depending on your system] need to download and install either or both of these Elisp modules:

php-mode
   css-mode

Presumption [for the purposes of this tip]:  IF you are using Emacs to edit PHP and/or CSS, THEN you know about and are using one or the other or both of these modules. If not, then you should probably give up now or seek professional help immediately.

Task:  Editing a PHP source file using Emacs can involve working in several source code language formatting modes, since it is common to mix PHP, CSS, (X)HTML, Javascript, and even MySQL query syntax in one PHP source file.

Rationale:  Although mixing languages in a single source file may on the face of it seem to violate the kind of *nixish organizational precepts that give us e.g. header (.h) and source (.c) files in C, sometimes painful experience has shown that the object oriented (OOD) precepts of "Encapsulation", "Isolation of Commonality", "Maintainability", and even (in some cases) "Human Readability" are all served by facilitating the mixing of languages within a single source file.

All that to say this: When editing a block of CSS code within a PHP file (using Emacs, of course), I have found it helpful to use the Emacs 'css-mode' Meta-Q key binding to format CSS rule blocks. However, when entering a multi-line CSS comment in the traditional 'C' style, it is useful to ask Emacs to use 'php-mode' Meta-Q to format the comments.

<?php 
$str = "example";
>
<style<
body {
  /* 
   * To format this comment block:
   * 1. Move the cursor to this line 
   * 2. Meta-X php-mode
   * 3. Meta-Q 
   *
   */
  margin:0;
  padding:0;
}

Summary:

• The Meta-Q keystroke in Emacs formats the text under the cursor in the current buffer into a 'paragraph' [block] conforming to some arbitrary standard established for whatever mode Emacs is running in (assuming, of course, that Meta-Q is mapped for that mode).
• When editing CSS, use the CSS mode to get nicely indented rule blocks.
• Switch to PHP mode to format C-style comments within the CSS block [STYLE element code].
• Probably should format the CSS first, then break the comments out such that they are surrounded by empty lines, since the php-mode formatting works most readably that way.…

Bash PS1 Prompt Set [correction]

##
## Set that annoying Cygwin Bash prompt...;)
##
##   There was an error in this string the previously 
##   published version - here is the corrected version.
##   This is Bash shell script code; it should go in the
##   file ~/.bashrc in the user's HOME directory - it 
##   could also go in  /etc/bashrc
##
export PS1='\[\033[32m\]\u@\h: \[\033[33m\w\033[0m\]
\$'

PHP Modules: Finding Syntax Errors and Module Dependencies

In constructing a web application with more than 2 PHP source modules, I found that it is useful to have a quick and easy way of finding a syntax error that may exist in one (or more) of a list of included modules.

Getting a List of PHP Includes

There is a function in PHP for this, which we will get back to in a moment. For right now I wanted to address some things we can do at a Bash prompt to troubleshoot why a script may not be sending any output to the browser on STDOUT.

That's a very common situation when you're working on a large application with many modules. It becomes important in those situations to be meticulous about syntax checking each change in any code before making additional changes.

I've been using the 'Lint' mechanism provided by PHP to syntax check PHP source code. It works like this: 

$php -l <fileName>

Now, some of you might already be seeing the implications of this. Hows about: 

$for fn in \
      `grep require frmPlayerInformation_body.09.inc\
      | perl -ne '/\"([a-zA-Z0-9.]+)\"\;/ && print "$1\n";'` ;;
 do 
      echo $fn ;;
      php -l $fn ;;
      echo "########" ;;
 done

The implications for scripting this operation from the command line are clear.

get_included_files()

PHP provides a function to get a list of module dependencies for a running script. It's called

get_included_files()

… and here's the URL for the docs: http://us2.php.net/manual/en/function.get-included-files.php

Problems with this Approach

There is at least one serious deficiency inherent in using the require, require_once, include, and include_once directives as the sole indicators of module dependency;  that is that, simply, the modules which are required or "included" due to HTML element attribute values.

Examples include the ACTION attrubute value(s) of HTML FORM element(s), the SRC attribute values for SCRIPT elements. and so on. IFRAME and LINK elements are also among those that can cause a module dependency within the HTML, CSS, or Javascript layer(s) generated by PHP code of a site.

Transparent SSH Login (*nix)

• Procedure for Creating Transparent SSH Logins

Standard I/O Redirection in Perl

This is an excerpt from the Perl manuals at perlDoc.perl.org concerning redirection of STDOUT and STDERR in Perl:

Because backticks do not affect standard error, use shell file descriptor syntax (assuming the shell supports this) if you care to address this. To capture a command's STDERR and STDOUT together:

$output = `cmd 2>&1`;

To capture a command's STDOUT but discard its STDERR:

$output = `cmd 2>/dev/null`;

To capture a command's STDERR but discard its STDOUT (ordering is important here):

$output = `cmd 2>&1 1>/dev/null`;

To exchange a command's STDOUT and STDERR in order to capture the STDERR but leave its STDOUT to come out the old STDERR:

$output = `cmd 3>&1 1>&2 2>&3 3>&-`;

To read both a command's STDOUT and its STDERR separately, it's easiest to redirect them separately to files, and then read from those files when the program is done:

system("program args 1>program.stdout 2>program.stderr");

The STDIN filehandle used by the command is inherited from Perl's STDIN. For example:

open BLAM, "blam" || die "Can't open: $!";
    open STDIN, "<&BLAM";

    print `sort`;

will print the sorted contents of the file "blam".

The I/O Operators manual also has some interesting information about standard file I/O in Perl.

Detecting active VNC server instances

I needed something to tell me what VNC server (vncserver()) instances were running, and on which DISPLAY ports, and with what resolution(s) (geometry), so I wrote one. Here is the HTMLized Perl source code:

#!/usr/bin/perl -w
######################################################################
## FILE:  findvncport.pl 

## DESC:  display information about VNC server instances
## VERS:  01
## DATE:  2009-05-13
## AUTH:  pdw@thesoftwaremaster.com
##############################################################################
##  USAGE NOTES:
##
##    This is a script to find out the connection port number and screen
##    geometry of any VNC server instances currently running on a host.  

##
##    This functionality is most useful to a user who needs to know what VNC
##    server instance(s) is(are) running, and on what port(s) - E.G.  at logon
##    (to a shell) time when a vncserver has been left running.
##
##    For convenience, the geometry of the X interface, the PID of Xvnc (the
##    actual X server invoked by vncserver), and such other info as we can
##    glean from the process listing on the host.
##

##    Note that this script only returns information about VNC instances
##    running under the UID of the user who runs the script.  The value of
##    the environment variable $USER is used to filter the process listing.
##    The user's $UID value is displayed, but is not used.
##
##    This program is designed to be run on a remote, ssh-accessible host
##    computer during the login and user account initialization process.
##
##  EXAMPLE:

##
##    I place this script in the .bash_login shell script that runs at user
##    login.
##
##
##  _TODO_: there is no buglist, yet, but there are some things need done to
##          this script right to begin with (i.e. the functionality is
##          marginal, and will almost certainly "break" the first time someone
##          tries to use it on some other platform or environment.  First on

##          the list of things to do must be: Fix the regular expression
##          parsing which finds the data in the process listing.  As the code
##          is now, these regex statements will break e.g. if the Xvnc command
##          line doesn't look like it expects. 2nd on the list has to be the
##          addtion of command line parameters to modify the output of the
##          script. :_TODO_
##
#############################################################################
##  REVISION HISTORY:

##
##     01: 2009-05-13 pdw
##         Initial version
##
#############################################################################
##
## Load up some environmental info...
$curruid = `echo \$UID`;

$curruser = `echo \$USER`;
@processes = `ps x -u \$USER`;
chomp($curruid);

chomp($curruser);

## @displays gets the data about whatever VNC displays are running
@displays = ();

while ($_ = shift(@processes)) {

 my $d = {};
 my $found = 0;
 chomp;

 next unless ($_);
  
 next unless (/^\s*(\d+).+Xvnc\s*(\:\d+)/)

  && ( $display = $2, $vncpid = $1 );

 # get desktop 

 m/-desktop(.+)-httpd/ 
  && ($desktop = $1);

 m/-geometry\s+(\d+x\d+)/
  && ( $geometry = $1 );

 m/-depth\s+(\d+)/
  && ( $depth = $1 );

 $d = {
  'Display'  => $display,
  'VNC PID'  => $vncpid,

  'Desktop'  => $desktop,
  'Geometry' => $geometry,

  'Depth'    => $depth,
 };
 push(@displays, $d);

}

## Display what we found out 
print "VNC server info for USER \'$curruser\':\n";
if (scalar(@displays)) {

 foreach my $disp (@displays) {
  foreach my $k (keys(%$disp))

  {
   print"  $k: \t".$disp->{$k}."\n";

  }
 }
} else {
 print "
  VNC server not found in process listing.

";
}

ls2csv.pl

#!/usr/bin/perl -w
#
# ls2csv.pl - show a listing of the PHP file
#            (*.inc and *.php) 
#             as a CSV table; no table headings included in 
#             output; no params defined
#
sub create_listing($) 
{
  my $xtn = shift;
  my @files = `ls -ghoG *.$xtn`;
  foreach my $f (@files) {
    chomp($f);
    $f =~ s/^\s*[-rw]+\s+\d\s+(.+)/$1/;
    $f =~ s/ /\",\"/g;
    $f =~ s/^(.)/\"$1/;
    $f =~ s/(.)$/$1\"/;
    print "$f\n";
  }
}

map { create_listing($_) } ("inc","php");