windows: installing the recovery console on xp

To install the Recovery Console in Windows XP, follow these steps:


1.    Insert the Windows XP CD into the CD-ROM drive.
2.    Click Start, and then click Run.
3.    In the Open box, type d:\i386\winnt32.exe /cmdcons where d is the drive letter for the CD-ROM drive. In the case of 'Microsoft Windows XP Professional x64 Edition, type d:\amd64\winnt32.exe /cmdcons where d is the drive letter for the CD-ROM drive.
4.    A Windows Setup Dialog Box appears. The Windows Setup Dialog Box describes the Recovery Console option. To confirm the installation, click Yes.
5.    Restart the computer. The next time that you start your computer, "Microsoft Windows Recovery Console" appears on the startup menu.

gdb: incredibly useful stuff!

For ages, I'd wanted gdb to search for the source file recursively inside a given "dir". Now I finally figured out how to accomplish this. Not by a 'recursive dir search', but by setting a 'substitute path' in gdb. This makes life so much easier now! Woohoo! :D

Much much thanks to this source for setting substitute-paths for gdb:

You know, by using a set substitute-path <library-source-path>
installed-source-path in the $HOME/.gdbinit file it is possible to
install the library source somewhere and have gdb replace the path
where the library's debug info says the source should be with where
you've installed the library's source.

On my system, for example, by using the 'strings' command, I'm able
to see that glibmm's debug info says that the source should be found
in /build/buildd/glibmm2.4-2.14.2/. I actually installed glibmm's
source in /usr/src/glibmm2.4-2.14.2. So by including the line set
substitute-path /build/buildd /usr/src in ~/.gdbinit, gdb has no
problems finding glibmm's source any more.

This works with all debuggers (even nemiver) as long as ~/.gdbinit is
processed by gdb when it starts up. :-)

So this is my current ~/.gdbinit file:

set substitute-path /sandbox/builds/appframework_dev /data/source/branches/appframework_dev

And I tested it on piidentity.net right away. IT'S AWESOME! Works right outta da box!

You can now automatically "list" code immedidately after attaching gdb to an httpd process - totally painlessly. This is so much better than having to set each "dir" in gdb for each source directory you wanted to "list" as you debugged it. I love "set substitute-path" - it rocks!


Some more cool gdb stuff I learnt today:

• interpreter-exec mi "-file-list-exec-source-files"
  (which is equivalent to "info sources")
• interpreter-exec mi "-file-list-exec-source-file"
  (which is equivalent to "info source")
• GDB has a ncurses-based GUI called TUI mode! Whoa!
  http://sources.redhat.com/gdb/current/onlinedocs/gdb_26.html
  

windows: how to schedule a high-frequency task

Task Scheduler doesn't let you schedule tasks with fine-grained frequencies. For example, you can't schedule a task to execute every minute, or every few hours. The maximum frequency that can be given to a task is "daily" which sucks because you need to run some programs more often than that (linux's cron is still the king!)

Here's the solution. It involves using the rather powerful "schtasks" windows command:

http://www.microsoft.com/resources/documentation/windows/xp/all/proddocs/en-us/schtasks.mspx?mfr=true

Here's what I used:

schtasks /create /sc hourly /mo 2 /tn "autoupdatesourcecode" /tr c:\tools\autoupdatesourcecode.bat

And this is my super-simple autoupdatesourcecode.bat:

cd d:\Codebase\trunk\pi\
d:
svn up

c++: auto_ptr::release()

auto_ptr::release()

The release() function removes ownership of the stored object from the
invoking auto_ptr and returns a pointer to the object. After a call to release(),
the pointed-to object is not automatically destroyed when the auto_ptr object
goes out of scope.

 -- Herb Schildt's C++ Programming Cookbook, Chapter 7, page 489

c++: deleting elements from a map

Q: Does std::map.erase() properly delete pointers, or does it create memory leaks?

A: It properly does not delete pointers, because it can't assume that nothing else points at the same thing. std::map cleans up the memory *it* explicitly allocated. *You* clean up the memory *you* explicitly allocated.


Here's how to safely delete all elements in a map, that will work for any container:

std::map<int, char*> Mappy;

int main()
{
    for(int Index = 0; Index < 10; ++Index)
    Mappy.insert(std::make_pair(Index, new char[10]));

    for(std::map<int, char*>::iterator MapItor = Mappy.begin(); MapItor != Mappy.end(); ++MapItor)
    {
        char* Value = (*MapItor).second;
        delete Value;
    }

    system("pause");
    return 0;
}

visual studio: how to show the full file path in the title bar

http://www.helixoft.com/blog/archives/32

batch file to fix WMI errors

There's a lot to learn about batch file scripting from this example!
source

net stop winmgmt

pause

c:

cd c:\windows\system32\wbem

rd /S /Q repository

regsvr32 /s %systemroot%\system32\scecli.dll

regsvr32 /s %systemroot%\system32\userenv.dll

mofcomp cimwin32.mof

mofcomp cimwin32.mfl

mofcomp rsop.mof

mofcomp rsop.mfl

for /f %%s in ('dir /b /s *.dll') do regsvr32 /s %%s

for /f %%s in ('dir /b *.mof') do mofcomp %%s

for /f %%s in ('dir /b *.mfl') do mofcomp %%s

mofcomp exwmi.mof

mofcomp -n:root\cimv2\applications\exchange wbemcons.mof

mofcomp -n:root\cimv2\applications\exchange smtpcons.mof

mofcomp exmgmt.mof

linux: adding swap space on-the-fly to your system

You might find that the swap partition you specified at install-time just isn't enough anymore. Maybe you've added more RAM to your machine and need to increase the swap partition accordingly. Or maybe you're upgrading your system to a version that uses more swap in relation to physical RAM. Perhaps you're running Oracle. In case your machine is swapping like mad and you just can't take it down right now to add more RAM, you can add more swap space on the fly using the following procedure. As an example, to keep the machine from running out of memory entirely and freezing up, we'll add 128 MB more swap space by creating a swap file. First we check out the memory usage:

[root@domain /root]# free -m
total       used       free     shared    buffers     cached
Mem:           251        242          8         22         11         32
-/+ buffers/cache:        198         52
Swap:          133        133          0

Make sure we have 128 MB laying around somewhere:

[root@domain /root]# df
Filesystem           1k-blocks      Used Available Use% Mounted on
/dev/hda9               132207     33429     91952  27% /
/dev/hda1                15522      2537     12184  17% /boot
/dev/hda6              6143236    739000   5092176  13% /opt
/dev/hda7              1035660    836204    146848  85% /usr
/dev/hda5              2071384    344048   1622112  17% /usr/local
/dev/hda8               303344     14439    273244   5% /var

OK, we're going to make a swap file in /opt by using dd to create a file 128 MB in size.

[root@domain /opt]# dd if=/dev/zero of=swapfile bs=1024 count=132207
132207+0 records in
132207+0 records out
[root@domain /opt]# ls -l
total 132364
drwxr-xr-x   20 usr-3 users        4096 May 22 10:46 usr-3
drwxr-xr-x    2 root     root        16384 Feb 21 07:04 lost+found
-rw-r--r--    1 root     root     135379968 May 29 11:52 swapfile

Let's not make it world-readable...

[root@domain /opt]# chmod 600 swapfile
[root@domain /opt]# ls -l
total 132364
drwxr-xr-x   20 usr-3 users        4096 May 22 10:46 usr-3
drwxr-xr-x    2 root     root        16384 Feb 21 07:04 lost+found
-rw-------    1 root     root     135379968 May 29 11:52 swapfile

Now we set up the swap area and enable it.

[root@domain /opt]# mkswap swapfile
Setting up swapspace version 1, size = 135372800 bytes
[root@domain /opt]# swapon swapfile

And voila! Twice as much swap as before.

[root@domain /opt]# free
total       used       free     shared    buffers     cached
Mem:        257632     254632       3000       2512      36172      15096
-/+ buffers/cache:     203364      54268
Swap:       268708     136512     132196

You can append a line like this to /etc/fstab to enable your swap file automatically at boot time:

/opt/swapfile           swap                    swap    defaults        0 0

source