how to delete last command from bash history

If you have ever typed something into a command prompt that you wished you hadn't - you may find it useful to know that you can delete it from ~/.bash_history very easily.

The command:

history -d offset

will delete the history entry at position offset.

# history
1 cd
2 history
3 ls -alhF
4 history
5 wget username:password@private.ftp.com/secret/file.tar.gz
6 history

so to delete the wget command (which contains a password) - just use:
history -d 5

# history -d 5
# history
1 cd
2 history
3 ls -alhF
4 history
5 history
6 history -d 5
7 history



This is (hopefully) the final update to an OLD post.  Sorta "pre-StackOverflow" internet.  

Checkout this question instead:
http://superuser.com/questions/384366/remove-a-certain-line-from-bash-history-file

^posted in the comments

The below is preserved only for hysterical accuracy


But suppose you KNOW you're about to enter a command you don't want to go into history. It'd be nice if you could just tack a little "hideme" modifer onto the front or tail of your command and be done with it. Unfortunately from what I've been able to google there is no such feature built into history or bash.

Naturally I made one.

TMP=$(history | tail -1 | awk '{print $1}') && history -d $TMP && \
paste_in_shell_and_replace_this_with_whatever_you_want_to_hide
And naturally someone smarter than me came along and found a better way to do it - THANKFULLY they posted a comment here to help us out (thanks Mitch!):

history -d $((HISTCMD-1)) && \
paste_in_shell_and_replace_this_with_whatever_you_want_to_hide

Rather than holding down backspace, you may find it useful to know that in bash Ctrl-W will delete from the cursor to the beginning of the previous word.

What I don't get, is that according man bash HISTCMD should be the CURRENT history number:

HISTCMD
The history number, or index in the history list, of the current command.

and yet in ALL my tests $HISTCMD is the "index in the history list, of the current command" +1

But it can still lead to two two useful aliases:

alias hideme='history -d $((HISTCMD-1))'
alias hideprev='history -d $((HISTCMD-2)) && history -d $((HISTCMD-1))'

Dig the sneaky:

# history
1 cd
2 history
3 ls -alhF
4 history
5 history
6 history -d 5
7 history
8 vi .bashrc
9 history
# echo password && hideme
password
# echo password
password
# hideprev# history
1 cd
2 history
3 ls -alhF
4 history
5 history
6 history -d 5
7 history
8 vi .bashrc
9 history
10 history

I know the blog's kinda been on Linux kick lately - some of that is coming from the new job - I'm using Linux more. But, I've been working on a little project in Eclipse - Java/SWT - and I'm getting to a point where I may have some useful learnings to post coming out of that. Or maybe not...

Internet Tablet, and all my xbox's are running fine...

I'd like to throw out some props to Ivie for sending me an email about one of my posts that she read. I try to post stuff that I myself have trouble finding out there on the interwebz - so it's always nice to hear from someone that finds it useful - thanks Ivie!

ubuntu disable hardware

I had a second sound card that kept getting picked up by apps under ubuntu as my primary audio device. In windows I sometimes use the game port on this pci sound card, but in general I don't even care if Linux detects it.

In ubuntu gnome, under System->Preferences->Sound
I had something like this:


In an unrelated effort, I had only recently discovered an important linux command - lsmod

The command list modules will display information about all loaded kernel modules. Kernel modules are dynamically loaded kernel functions, such as a device driver.

When I looked through the list of loaded kernel modules on my system:

lsmod | less

I found this:

snd_ens1370 21536 0
gameport 16776 1 snd_ens1370
snd_ak4531_codec 9856 1 snd_ens1370
snd_pcm 80388 5 snd_ens1370,snd_intel8x0,snd_ac97_codec

There was no doubt in my mind - I needed to stop the kernel from loading the module snd_ens1370.

I had considered just deleting it all together:

$ locate 1370
/lib/modules/2.6.22-14-generic/kernel/sound/pci/snd-ens1370.ko
/usr/src/linux-headers-2.6.22-14-generic/include/config/snd/ens1370.h
/usr/share/alsa/cards/ENS1370.conf

But it turns out there is a more elegant way.

To disable hardware in ubuntu - blacklist the module.

Take a look at, /etc/modprobe.d/blacklist

To disable my Ensoniq sound card in ubuntu - I added the following lines:

# disable my PCI ensoniq sound card
blacklist snd_ens1370

then just reboot...

how does bash work

When evoked the Borne Again Shell can launch one of two different types of interactive shells, login or non-login.

These descriptions are based on my experiences with a variety of Debian & Fedora based environments - each has their own peculiarities in their implementation of bash. I'll do my best to be "generic"

When you login via tty, ssh, or su --login - your $SHELL is launched for you. This is called a "login" shell, and it will automatically source the following files:

1) /etc/profile

then

2) ~/.profile or ~/.bash_profile
(but generally not both, one will take "precedence")

When you launch /bin/bash by some other means (xterm, konsole, su, or even typing /bin/bash) it is considered non-login and it WILL source .bashrc

It is VERY common for ~/.profile (or ~/.bash_profile) to source ~/.bashrc by either:

. ~/.bashrc

or

source ~/.bashrc

You can use source either way - in both interactive and non-interactive shells.

/etc/profile may source lots of other files. Sometimes /etc/bashrc (or /etc/bash.bashrc) and sometimes even ~/.bashrc - so watch out!

Your system may not have all these files - or they may have different names. Try:

ls -al /etc/ | grep bashrc
ls -al /etc/ | grep profile
ls -al ~ | grep bashrc
ls -al ~ | grep profile

to get some different ideas.

the command "su -" is short hand for "su --login root" or "switch user to root and launch a login shell"
it is NOT "switch to super user and load environment variables" (even if that may be the case on some systems)

3RLOD Error 0020 X Clamp Replacement

And so, it was my turn:


For a used 360, I'm actually pretty happy it lasted as long as it did. Manufacture date was 2/06 - so there's nothing holding me back now.

Funny thing, this is actually how my FIRST xbox got modded. When it broke, it was out of warranty, so I had nothing keeping me from opening it up. XBMC is the best thing I ever did for my entertainment center.

In this case the interwebz says I need an X-Clamp Replacement - so you know... whatever.

I went with RBJ's MKIII method. Which is extremely well documented, so I didn't really take many pictures. (Update: Last I checked RBJ had taken down his tutorial, which is too bad - I sent him a message. Lamma has a good one up, which is essentially the same thing. However, it should be noted I did NOT buy the kit he's selling - although I'm sure it's worth every penny - you can get the parts anywhere. It's the work of removing the x-clamp, not the tools/equipment you use, that fixes your xbox.)

I used the following hardware from Lowe's:
2 packs - M5-.8x20mm - Oval Head Phillips - Sales # 138573 - $.92 each pack (Qty:2)
2 packs - M5-.8x16mm - Oval Head Phillips - Sales # 138566 - $.68 each pack (Qty:2)
5 packs - 5mm Flat Washers - Part # 138319 - $.56 each pack (Qty:10)


I spent probably more time than I should have cleaning the old thermal paste off the chips & heat sinks. Goo-Gone and 99% alcohol. Then I used a razor to spread a very thin even layer of some generic thermal paste on the CPU and GPU. I just used what I had lying around instead of the "artic silver" stuff everyone talks about.

Drilling the holes in the case was surprisingly pretty easy - I used a 1/4" bit for a pilot hole, then opened it up to 3/8's. Using the tape to hold the bolts in place while I got the board in place also went pretty smooth.

I accidentally screwed the CPU head sink down backward on my first try putting things back together (heat tube AWAY from the GPU) - but once I got everything screwed down... It booted up on the first try - green lights all around.

Been running great for 3 days - posted success.

BTW, I start the new job @ Rackspace on Monday.

Reset BIOS password on an IBM Thinkpad T23

I had really hoped I could reset the supervisor password on a spare IBM T23 laptop we had around the office by - disconnecting the CMOS battery or shorting a jumper. Anything besides the procedure described on sodoityourself.com

But apparently there's no way to "reset it" you just have to build yourself a "testpoint" jig and read the encrypted data directly off the EEPROM connected to the main board.

So I picked up a few parts from RadioShack and went to work. BTW, The password turned out to be XPBIOS.


But, I feel it's important to note, I'm an idiot.

The image you see above here is NOT of a working cable. It is in-fact the improperly constructed cable which was later rebuilt and used to successfully dump the contents of the actmel eeprom on the IBM Thinkpad.

Apparently there isn't much standardization to diagramming a serial connector. It's hard to tell if the flat picture you're looking at is supposed to be a male or female connection. And even worse - true circuit diagrams will often show the BACK of the connector - i.e. they draw it so you would be looking at where the "wires" are ACTUALLY connecting to the BACK of the connector.

Crazy.

Your only real hope is to know the pin numbers of an rs232 cable. Thankfully, almost ALL diagrams will include pin numbers to specify the orientation of the connector and avoid this type of confusion.

Well... that doesn't help you much if you don't know which pin is which on your cable. So here is a picture of an rs232 / db9 / 9-pin serial cable - with both male and female connectors labeled pin 1, pin 5, pin 6, and pin 9.


Not even wiki has this kind of information...

Nokia 770 OS2007HE - Can't change Regional settings

Flashed my Nokia tablet with the new '07 OS "Hacker Edition" - it's been running strong all night.

The first issue I came into was a problem changing the Regional settings and Device language from English (United Kingdom) to English (USA). I would get an error:

Device storage memory full.
Delete some data to free memory.

Total rubbish, the memory was fine. Not surprisingly all this little drop down does is change a setting in a config file. Install xTerm, gainroot, find the file, edit the setting, reboot and now my date displays month/day/year - no problem.

**UPDATE** Ivie found an even simpler solution documented on her blog - you may want to try that first.

I found an updated version of xTerm that draws the screen quite a bit better, and supports color. To install xTerm on a Nokia 770 0S2007HE go to maemo-hackers and click on the .install link for "bora"

To gain root access on a Nokia 770 OS2007HE use the same old 2006 "becomeroot" package - download it here.

Then just open up xTerm, su gainroot and edit the following file:

/etc/osso-af-init/locale

change the last two lines to:

export LANG=en_US
export LC_MESSAGES=en_US

that is... as long as you live here in the states.

I'll probably have more updates as I run into more snags installing and reconfiguring all my packages. To-Do list updated.

Configure Nokia 770 Internet Search Applet

Configure Nokia 770 Internet Search Applet
Originally uploaded by clay.gerrard@sbcglobal.net

Add additional search engines to your Nokia 770 Internet Search Applet by creating carefully crafted .xml documents in /usr/share/mis. You can even make custom icons!

To add IMDB, Amazon, eBay, NewEgg & Google Maps (for Nokia 770) download internetsearch.zip from my media fire account, and add the extracted files to /usr/share/mis

Extract the files into a folder on your Nokia 770's memory card (something like internetsearch). Then you'll need to fire up xTerm and becomeroot. Copy the files to /usr/share/mis using a command similar to this:

cp /media/mmc1/internetsearch/* /usr/share/mis/

Reboot for changes to take effect.

I've added my favorite search engines. I particularly like the Google Maps for Nokia 770 - the trick to using this effectively is to "zoom in" to 150% using the buttons on top. Then instead of "dragging" around the map - you click where you want to re-center.

This is an update and repackage of work started by Moonshine.

For more details about the format of these .xml files reference this post on internet tablet talk.