Posts for the month of July 2008

Stopping a Windows Executable from Running

To prevent a file from being created, in the past I have created a folder with the same name. This lets you stop a file from running (the example used is a worm executable):

  1. Create a registry key with the name of the process you want to prevent to execute. Ex.: calc.exe
    HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Image File Execution Options\calc.exe 
  1. Under this new key you've just created, create a SZ value called "Debugger" and set it to the following value:
    SZ Debugger = "cmd.exe /c echo  %time% %date% calc.exe >> c:\ExecBlocked.log"

From with slight mods by me.

Random Unix/Linux Tips

Yeah, that's pretty much the subtitle of this blog, but I found another that has similar stuff:

My favs (I'm copying in case the site goes down):

Convert a static lib (.a) into a dynamic one (.so)

gcc -shared -o \
	-Wl,-soname, \

Create PNGs from a pdf presentation

gs -dSAFER -dBATCH -dNOPAUSE -dTextAlphaBits=4 \
    -dGraphicsAlphaBits=4 \
    -r85 -q -sDEVICE=png16m -sOutputFile=icfp-pg%02d.png \

Read a damaged CD/DVD valid parts and get the rest with rsync

As is often the case, when I bring some burned CD/DVD 
from work, I find out that its bad at some offset.
I came up with this Perl script:

#!/usr/bin/perl -w
use strict;

my $i=0;

select((select(STDOUT), $| = 1)[0]);

system("dd if=/dev/zero of=zero bs=2K count=1");

my $step = 1;

print "Sector:             ";
while(1) {
 system("dd if=/cdrom/BadSector of=sector bs=2K skip=$i".
    "count=1 >/dev/null 2>&1");
 if ($? == 0) {
     print sprintf("\b\b\b\b\b\b\b\b%08d", $i);
     system("cat sector >> data");
     $step = 1;
     $i += $step;
 } else {
     system("cat zero >> data");
     $step += $step;
     $i += $step;
     print "\nJumped over $step\nSector:             ";

With the CD/DVD mounted on /cdrom/, it will slowly but 
effectively copy sector by sector of the file mentioned 
in the 'dd' line into the file called 'data'. Reading 
sector-sector proves to be enough to correct a multitude 
of read-errors on my DVD reader, but even if that isn't 
enough, it will quickly jump over the problem areas
in the DVD, writing blank 'sectors' to mark the jumps.

After that, rsync can save the day:

rsync -vvv -B 131072 -e ssh \
	[email protected]:/path/todata data