Hacking For Kids

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A programmer’s wife sends him to the grocery store with the instructions, “get a loaf of bread, and if they have eggs, get a dozen.” He comes home with a dozen loaf of bread and tells her, “they had eggs.”

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Any JavaScript programmers out there? I'm trying to figure out why x[count] changes in the next loop iteration without me touching it when I do this:

for (var count = 0; count < 7; count++){
x[count] = y[count];
}

but it stays the same when I do this:

for (var count = 0; count < 7; count++){
x[count] = y[count] + 0;
}

Yes, I sat here for hours banging my head and all I added was a "+ 0". When is the last time "+ 0" solved anything? Did JavaScript all the sudden say "hey, lets treat this as a variable instead of a string!", or maybe I somehow created a reference?

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I was looking through old pictures of mine while stumbling across this. Yes, I made tea with my lava lamp at work. Yes, it was tasty.

I powered up an old box I used to play around on and found a file called ice.cpp. I guess this is what Vanilla Ice would come up with if he were a C++ programmer? Man, I used to do some weird stuff…

stop();
if(collaberate && listen){
  ice = back;
  width(new invention);
  something.grabs(me, "tightly");
  harpoon>>daily>>nightly;
  if(stop){
    lights = 0;
    VanillaIce.glow = 1;
    rockMike("vandal");
    lights = 1;
    Chump.wax("candle");
  }
}

stop();
if(collaberate && listen){
  ice = back;
  width(new invention);
  something.grabs(me, "tightly");
  harpoon>>daily>>nightly;
  if(stop){
    lights = 0;
    VanillaIce.glow = 1;
    rockMike("vandal");
    lights = 1;
    Chump.wax("candle");
  }
}

Can you dig it? The Warriors … good movie.

Feel free to comment!

http://www.hackingforkids.com/?p=50209

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Kristoff’s Linux Tips and Tricks
I’ve been collecting tips and tricks over the years working as a linux engineer. A lot are pretty simple, some are a bit more advanced. Feel free comment with any questions or suggestions! Ba…

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I’ve been collecting tips and tricks over the years working as a linux engineer. A lot are pretty simple, some are a bit more advanced. Feel free comment with any questions or suggestions!

Bash Tricks

Find the largest files on a system

This will output a very nice stylized list like so:

[root@upgrayedd ~]# find / -size +100M -printf '%k %p\n' 2> /dev/null | sort -nr | perl -ne 'if ( /^(\d+)\s+(.*$)/){$l=log($1+.1);$m=int($l/log(1024)); printf     1.0 G        ********************  /home/kris/Videos/Miro/Uploads-by-ComputerHistory/videoplayback-upn=m_QO_nJsugQ_sparams=cp,id,ip,ipbits,itag,.84494F724332988A7D79CF622EB53CFD5709DA5C.mp4
 869.0  M        ********************  /home/kris/Videos/Miro/Uploads-by-ComputerHistory/videoplayback-upn=Z7EuUGE7A8c_sparams=cp,id,ip,ipbits,itag,.3499AD411FFA0B830460CB619600181C21CADA7C.mp4
 700.6  M        ********************  /home/kris/Videos/Miro/Uploads-by-ComputerHistory/videoplayback-upn=pp_vMJGe03w_sparams=cp,id,ip,ipbits,itag,.A29E845C92F058212D3CEA59844B3165A7C93C79.mp4
 420.6  M         *******************  /home/kris/Videos/Miro/Hak5--HD-MP4-/hak5--1213--how-to-remove-amazon-from-your-ubuntu--hd720p30.h264.mp4
 396.9  M         *******************  /home/kris/Videos/Miro/Hak5--HD-MP4-/hak5--1215--use-wine-in-computers--hd720p30.h264.mp4
 147.5  M           *****************  /home/kris/montagueot.tar.gz
 113.2  M           *****************  /home/kris/Dropbox/Camera Uploads/2012-09-12 20.24.02.m4v
 110.6  M           *****************  /var/cache/yum/i386/17/fedora/gen/filelists_db.sqlite
 110.3  M           *****************  /home/kris/Videos/Miro/TEDTalks--hd-/BobbyGhosh_2012X-480p.mp4
 108.4  M           *****************  /home/kris/Dropbox/Camera Uploads/2012-12-30 22.06.10.m4v
 108.2  M           *****************  /home/kris/Videos/Miro/Nixie-Pixel-Geekbuzz--HD-MP4---30fps-/nixiepixel--0046--pelican-case-u100--hd720p30.h264.mp4
 104.3  M           *****************  /home/kris/Videos/Miro/TEDTalks--hd-/JonathanTrent_2012G-480p.mp4
 100.1  M           *****************  /usr/lib/locale/locale-archive

[root@upgrayedd ~]# find / -size +100M -printf '%k %p\n' 2> /dev/null | sort -nr | perl -ne 'if ( /^(\d+)\s+(.*$)/){$l=log($1+.1);$m=int($l/log(1024)); printf     1.0	G	     ********************  /home/kris/Videos/Miro/Uploads-by-ComputerHistory/videoplayback-upn=m_QO_nJsugQ_sparams=cp,id,ip,ipbits,itag,.84494F724332988A7D79CF622EB53CFD5709DA5C.mp4
 869.0	M	     ********************  /home/kris/Videos/Miro/Uploads-by-ComputerHistory/videoplayback-upn=Z7EuUGE7A8c_sparams=cp,id,ip,ipbits,itag,.3499AD411FFA0B830460CB619600181C21CADA7C.mp4
 700.6	M	     ********************  /home/kris/Videos/Miro/Uploads-by-ComputerHistory/videoplayback-upn=pp_vMJGe03w_sparams=cp,id,ip,ipbits,itag,.A29E845C92F058212D3CEA59844B3165A7C93C79.mp4
 420.6	M	      *******************  /home/kris/Videos/Miro/Hak5--HD-MP4-/hak5--1213--how-to-remove-amazon-from-your-ubuntu--hd720p30.h264.mp4
 396.9	M	      *******************  /home/kris/Videos/Miro/Hak5--HD-MP4-/hak5--1215--use-wine-in-computers--hd720p30.h264.mp4
 147.5	M	        *****************  /home/kris/montagueot.tar.gz
 113.2	M	        *****************  /home/kris/Dropbox/Camera Uploads/2012-09-12 20.24.02.m4v
 110.6	M	        *****************  /var/cache/yum/i386/17/fedora/gen/filelists_db.sqlite
 110.3	M	        *****************  /home/kris/Videos/Miro/TEDTalks--hd-/BobbyGhosh_2012X-480p.mp4
 108.4	M	        *****************  /home/kris/Dropbox/Camera Uploads/2012-12-30 22.06.10.m4v
 108.2	M	        *****************  /home/kris/Videos/Miro/Nixie-Pixel-Geekbuzz--HD-MP4---30fps-/nixiepixel--0046--pelican-case-u100--hd720p30.h264.mp4
 104.3	M	        *****************  /home/kris/Videos/Miro/TEDTalks--hd-/JonathanTrent_2012G-480p.mp4
 100.1	M	        *****************  /usr/lib/locale/locale-archive

Change the “500M” to whatever you want. Swich the M to a G if you’d like to search for gigabyte sized files.

find / -size +500M -printf '%k %p\n' 2> /dev/null | sort -nr | perl -ne 'if ( /^(\d+)\s+(.*$)/){$l=log($1+.1);$m=int($l/log(1024)); printf  ("%6.1f\t%s\t%25s  %s\n",($1/(2**(10*$m))),(("K","M","G","T","P")[$m]),"*"x (1.5*$l),$2);}'

find / -size +500M -printf '%k %p\n' 2> /dev/null | sort -nr | perl -ne 'if ( /^(\d+)\s+(.*$)/){$l=log($1+.1);$m=int($l/log(1024)); printf  ("%6.1f\t%s\t%25s  %s\n",($1/(2**(10*$m))),(("K","M","G","T","P")[$m]),"*"x (1.5*$l),$2);}'

Change to the last working directory

Useful if you temporarily change to a directory and want to get back to where you were.

cd -

cd -

Filter out comments and blank lines from configuration files

Tired of all those comments and blank lines in configuration files? Try this out for a clearer view.

grep -Ev "^#|^$" foobar.conf

grep -Ev "^#|^$" foobar.conf

Filter out comments and blank lines from configuration files w/ syntax highlighting

Want syntax highlighting? Check this out. Type “:q!” to exit vim.

grep -Ev "^#|^$" foobar.conf | vim -Rc 'set ft=conf' -

grep -Ev "^#|^$" foobar.conf | vim -Rc 'set ft=conf' -

Convert epoch time to human time

That ugly large number is epoch.

date -d @1317755469

date -d @1317755469

Delete files older than 7 days

This will find all files ending with .gz. Change that to whatever extension you want. Remove everything after the “+7″ to test and not actually delete anything (highly recommended).

find /var/log/*.gz -type f -mtime +7 -exec rm {} \;

find /var/log/*.gz -type f -mtime +7 -exec rm {} \;

See if a package is available on a RedHat system

yum list packagename

yum list packagename

Clear a Dell DRAC ESM log

omconfig system esmlog action=clear

omconfig system esmlog action=clear

Find what domains in a list are not legit

Put a list of domains into domains_file, one domain per line.

for x in $(cat domains_file); do host $x > /dev/null ; if [ $? -ne 0 ]; then echo "$x"; fi; done

for x in $(cat domains_file); do host $x > /dev/null ; if [ $? -ne 0 ]; then echo "$x"; fi; done

Reverse your grep

This will show everything in a file except what you’re searching for.

grep -v "dumb monkey" filename

grep -v "dumb monkey" filename

Search for multiple things

You can do some fun stuff with regular expressions and grep. I’ve found this the most useful.

egrep "dog|cat|capybara" filename

egrep "dog|cat|capybara" filename

OR

grep -E "dog|cat|capybara" filename

grep -E "dog|cat|capybara" filename

List files in order by date

This will show the newest files first.

ls -lt

ls -lt

This will show the oldest files first.

ls -ltr

ls -ltr

E-mail with attachment

This will let you send a file via commandline with an attached file. Note that the file you want to attach is the “origname.txt” and the second filename can be whatever you want (or the same as the original filename). Either way, you have to specify a filename twice.

(echo "Body of message here"; uuencode origname.txt attachmentname.txt) | mail -s "Subject Goes Here" user@example.com

(echo "Body of message here"; uuencode origname.txt attachmentname.txt) | mail -s "Subject Goes Here" user@example.com

Send an email with attachment and body

Same as above, except put your actual message into body.txt.

(cat body.txt; uuencode origname.txt attachmentname.txt) | mail awesome_person@gmail.com

(cat body.txt; uuencode origname.txt attachmentname.txt) | mail awesome_person@gmail.com

Quickly show how many CPUs a box has:

cat /proc/cpuinfo | grep processor | wc -l

cat /proc/cpuinfo | grep processor | wc -l

Find out what is taking up free space

Keep on adding to the path at the end until you find the culprit(s):

du -hx --max-depth=1 /

du -hx --max-depth=1 /

Remove leading whitespace from file

Where pizza_rocks is filename:

cat pizza_rocks | sed -e 's/^[ \t]*//'

cat pizza_rocks | sed -e 's/^[ \t]*//'

To sort a file by column

Where the number 2 is the number of column to sort by:

sort -k2 awesomefilename

sort -k2 awesomefilename

Is echo/bash displaying things on different lines when it shouldn’t be?

Set the internal field separator (IFS) variable back:

IFS=$'\n'

IFS=$'\n'

Use last command starting with foo

Not recommended for potentially dangerous commands such as rm:

!foo

!foo

To change the hostname on a Cent/RedHat box

Recommended restart after change instead of changing $HOSTNAME.:

vim /etc/sysconfig/network

vim /etc/sysconfig/network

“Disown” a job

So you can close the terminal and it will continue to run (where jobID is the job you want disowned):

jobs; disown %jobID

jobs; disown %jobID

Create a large list of IPs

ex. 255.255.0.0, each on newline:

echo -e 192.168.{1..255}.{1..255} >> ips; tr ' ' '\n' < ips > endresult

echo -e 192.168.{1..255}.{1..255} >> ips; tr ' ' '\n' < ips > endresult

Execute command on each line in file

Where zaphodbeeblebrox is filename:

for LINE in $( cat zaphodbeeblebrox ) ; do echo "$LINE" ; done

for LINE in $( cat zaphodbeeblebrox ) ; do echo "$LINE" ; done

Show free memory (physical and swap) on a box

free -m

free -m

To override an alias

Use single quotes around command:

'cp' -rf ~/illegalmp3s /media/thumbdrive

'cp' -rf ~/illegalmp3s /media/thumbdrive

OR use a backslash at the beginning of the line

\cp -rf ~/illegalmp3s /media/thumbdrive

\cp -rf ~/illegalmp3s /media/thumbdrive

To tar gzip a folder

tar czvf roflcopter.tar.gz roflcopter/

tar czvf roflcopter.tar.gz roflcopter/

To decompress a tar.gz file

tar xvfz monkeydoodles.tar.gz

tar xvfz monkeydoodles.tar.gz

To turn off the PC speaker beep in BASH

setterm -blength 0

setterm -blength 0

Paswordless SSH login

(host A, host B)

ssh-keygen -t rsa (on A), cat .ssh/id_rsa.pub | ssh username@B 'cat >> .ssh/authorized_keys'

ssh-keygen -t rsa (on A), cat .ssh/id_rsa.pub | ssh username@B 'cat >> .ssh/authorized_keys'

Generate SHA password for LDAP

As root, hax0r is password)

slappasswd -h {SHA} -s hax0r

slappasswd -h {SHA} -s hax0r

Download entire website w/ bandwidth speed limit

wget --wait=20 --limit-rate=20K -r -p -U Mozilla http://www.hackingforkids.com

wget --wait=20 --limit-rate=20K -r -p -U Mozilla http://www.hackingforkids.com

To see what is in the clipboard buffer every 2 seconds

Useful when pasting to IRC

watch -n 10 xclip -o

watch -n 10 xclip -o

Execute command on each line in file “foo”

for line in `cat foo`; do command $line; done;

for line in `cat foo`; do command $line; done;

To check what kind of architecture a system is running

uname -a

uname -a

To pull files via scp

Example is to pull all files in one dir into home directory on local machine.

scp username@hostname:Documents/* ~

scp username@hostname:Documents/* ~

To see what process is listening on a port

Where tcp is protocol (can use udp) and 80 is port:

sudo fuser -v -n tcp 80

sudo fuser -v -n tcp 80

Show line numbers with less

less -N file

less -N file

To show stdout and stderr to screen and also write to file

-a flag appends to file. Note that “tee” may need to be installed.

programname | tee -a logfilename 2>&1

programname | tee -a logfilename 2>&1

To get a list of users on a system

cut -d: -f1 /etc/passwd

cut -d: -f1 /etc/passwd

To show only unique lines in a file

Foobar is filename

sort foobar | uniq

sort foobar | uniq

To set the number for a screen session

When showing as a list

Ctrl+a, type a colon, then type in "number 24" (no quotes & 24 is win #)

Ctrl+a, type a colon, then type in "number 24" (no quotes & 24 is win #)

Color manpages

1) Install most (apt-get install most), 2) Add the following to ~/.bashrc:

export MANPAGER="/usr/bin/most -s"

export MANPAGER="/usr/bin/most -s"

To push remotely a file to another server

copyme is file to be copied

scp /usr/local/bin/copyme username@remoteservername:/home/username/

scp /usr/local/bin/copyme username@remoteservername:/home/username/

To remove leading spaces from a file

sed 's/^[ \t]*//;s/[ \t]*$//' filename

sed 's/^[ \t]*//;s/[ \t]*$//' filename

To do a direct filesystem copy

Where sda is the source and sdb is the destination

dd if=/dev/sda of=/dev/sdb

dd if=/dev/sda of=/dev/sdb

To grep all .gz files in one directory

zgrep 'ohai' *.gz

zgrep 'ohai' *.gz

To change file attributes on a file

Example will lock a file down so even root can’t delete (uses +/- to add/remove)

chattr +i filename

chattr +i filename

To create a text dialog

You can also create menus for input and other cool things:

dialog --title 'Message' --msgbox 'Hello, world!' 5 20

dialog --title 'Message' --msgbox 'Hello, world!' 5 20

To append an IP range to a file with bash brace expansion

echo -e 192.168.1.{1..255}"\n" >> out

echo -e 192.168.1.{1..255}"\n" >> out

Vim Tricks

Delete whitespace from the beginning of lines

:%le

:%le

To map a function key

Press the key first to see if your window manager traps it. This will execute the current file.

:map  : !%:p

:map  : !%:p

Execute the script that is currently being edited

:!%:p

:!%:p

Toggle visible whitespace

:set list!

:set list!

Show manpage for command under cursor

K

K

Run make in current directory

:make

:make

Show line numbers

:set number

:set number

Turn off line numbers

:set nonumber

:set nonumber

To remove blank lines

:v/./d

:v/./d

Change VIM color scheme

“Colo” is short for “colorscheme”. Type that in, space, then control + d to show a list of options. Then start typing in a scheme you want and tab out the rest

:colo
adrian        wombat256mod  default       elflord       morning       peachpuff     slate
codeschool    blue          delek         evening       murphy        ron           torte
vividchalk    darkblue      desert        koehler       pablo         shine         zellner

:colo
adrian        wombat256mod  default       elflord       morning       peachpuff     slate
codeschool    blue          delek         evening       murphy        ron           torte
vividchalk    darkblue      desert        koehler       pablo         shine         zellner

:colo evening

:colo evening

Write + execute script

This will save and execute a script you are currently working on. Add this to your ~/.vimrc. Press F8 in VIM to use.

:map!   :w :!%:p
:map   :w :!%:p

:map!   :w :!%:p
:map   :w :!%:p

Sometimes this doesn’t work right, so I normally use this as a backup instead. This won’t save the file first, so it’ll execute whatever you have saved already. Press F7 in VIM to use.

:map  :!%:p
:map!  :!%:p

:map  :!%:p
:map!  :!%:p

Just For Fun

Sample different cowsay “cows”

Press Enter for next cow

for x in $(ls /usr/share/cowsay/cows); do cowsay -f $x Oh dang.; input; done

for x in $(ls /usr/share/cowsay/cows); do cowsay -f $x Oh dang.; input; done

To output banner-like messages (w/ colors).

You can also output in HTML and IRC colors.

toilet -w 200 -f bigmono9 --gay Hello world!

toilet -w 200 -f bigmono9 --gay Hello world!

A dancing 3d juggler

For the holidays!

/usr/lib/xscreensaver/juggler3d -pattern "2 2"

/usr/lib/xscreensaver/juggler3d -pattern "2 2"

Other

Use less when using mysql interactively

When using mysql, use command:

pager less;

pager less;

In HP-UX, if the backspace simply enters a ^? instead of erasing, do the following

Good idea to add to your ~/.profile

stty erase ^?

stty erase ^?

Get MAC/IP of DRAC

When ssh’d into system

omreport chassis remoteaccess

omreport chassis remoteaccess

Starting January 19th, I'm going to refrain to the best of my abilities from using Facebook and G+ at all, as well as watching TV and playing video games. I'm going to take this time to up my game and become better. Better at what? Well, better at what I do, and better at what I'd like to be doing. I'm going to focus on doing my job better as well as getting back into shape. I now have a fiance (and a puppy) to support and I've got a good start already. I'm going to shape up to make the best of my life, to make things financially right, and to let myself have some fun with what I do. Life is full of potential and opportunities for us all. You may not think so, but it's true for even you. Social networking has been sort of a sickness for me in particular lately, and it's time to stop.

I remember when I was younger, when I had nothing else I wanted to do other than ride my bike, split wood, work out, and read computer books. I had focus back then because there wasn't much to distract me. There was no Facebook, there was no 42" TV sitting in front of me, and there weren't a lot of really fun games sitting at my disposal. I was kickass, I was on my game, and I've slipped. I want to be that person again. I desperately want to be who I was, because I'm ashamed of who I am now.

I haven't seen a lot of you in years, yet I read what you're doing every day. Unless you're part of my life, it's time to let go of being "friends". If you want to actually hang out sometime, message me with your email address or number, or just get get my number from my profile. I'll be unfriending most of you after a month.

The technicals? I'm going to block social networking sites on my router as well as blackhole the sites in my hosts files. I'm also going to get rid of the apps on my phone. I'd get rid of Internet here at home, but my job kinda requires it, and it's going to be useful for learning new things. I'm also going to get rid of Netflix for a bit, which I should do anyway since I rarely watch it. And last, I'm going to unplug the mess that is my entertainment center, less the wireless router.

Seriously though, if you ever want to hear of me again … ever, give me some contact information. I have a suspicion that I may deactivate my Facebook account after all of this. And if we've never hung out before, it doesn't matter. Good breweries are in abundance around here, and I'd be glad to meet some of you there.

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