Displaying only matching regex with sed

sed -n 's/stuff\(.*\)more stuff/\1/p'

This will only show the data matched by the parenthesised expression.

The following example shows only unique filenames leaving out paths:
find . -iname "*file*"| sed  -n 's/.*\/\(.*\)$/\1/p' | sort | uniq | less

The watch command

Wow, what a useful command I just learned of.
Watch executes any task at a given interval, like a hassle-free on the fly cron job.
For instance to display your arp table and refresh every 10 seconds:

watch -n 10 arp -a

Mass file renaming

I just learned that Linux's rename command can use regular expressions to  substitute file name parts.

(-v tells you what was renamed)
rename -v 's/FROM/TO/g'  *

This will replace the word FROM to the word TO in all file names.

Make inplace changes with sed

If you want sed to actually make changes to a file, not just show the output on stdout, use the -i option.  If you add an extension, it will be used to create a backup of the file before changing it.

-i is inline
-i.bak (No space) will make a .bak

sed -i.bak 's/findthis/changetothis/' myfile

Send signal to dd to view progress

If you start dd and want to see how far its progressed send it a USR1 signal.


The loop shown doesn't work for me, but this does "sudo killall -USR1 dd" albeit not in a loop. There is also some similar documentation in the man page for dd (or the help page one).

One line web server using Python

Python 2.x:
python -m SimpleHTTPServer

Python 3.x: *
python -m http.server 8000


From http://www.garyrobinson.net/2004/03/one_line_python.html

*The 3.x option doesn't work for me as I have no "http" module, but I can use:
python -m BASEHTTPServer instead, pydoc -k http will show all modules with http in the name.

Great Android programming video

It's two hours long, and over a year old so may be getting out of date, but this is really good.


Youtube video

USB Sniffing

This page details how to sniff usb data in Linux. Under Ubuntu some things have changed. You can use lsusb to see the USB information for your devices, and the folder under /sys has changed to /sys/kernel/debug/usb/usbmon

Transparent backgrounds with CSS

Simple method: 

#lightbox {
   background: white;
   border: 20px solid rgba(0,0,0,0.3);
}

There may be more to it depending on what you want to accomplish 

(where does the transparency begin and end?):

http://css-tricks.com/7423-transparent-borders-with-background-clip/ 

Disable broken scrollbars in Ubuntu 11.04

The code below will supposedly start applications that don't work 

with the new Ubuntu 11.04 overlay scrollbar (such as eclipse), 

without the scrollbar. 

LIBOVERLAY_SCROLLBAR=0 /usr/bin/program_to_run

Monitor the light sensor in Android

Haven't tried it yet, but
From this post

Only two files:
Code:

package com.exercise.AndroidLightSensor;

import android.app.Activity;
import android.content.Context;
import android.hardware.Sensor;
import android.hardware.SensorEvent;
import android.hardware.SensorEventListener;
import android.hardware.SensorManager;
import android.os.Bundle;
import android.widget.TextView;

public class AndroidLightSensor extends Activity {
 
 SensorManager mySensorManager;
 Sensor myLightSensor;
 TextView textLightSensorData;
 
   /** Called when the activity is first created. */
   @Override
   public void onCreate(Bundle savedInstanceState) {
    
       super.onCreate(savedInstanceState);
       setContentView(R.layout.main);
       TextView textLightSensor = (TextView)findViewById(R.id.lightsensor);
       textLightSensorData = (TextView)findViewById(R.id.lightsensordata);
      
       mySensorManager = (SensorManager)getSystemService(Context.SENSOR_SERVICE);
       myLightSensor = mySensorManager.getDefaultSensor(Sensor.TYPE_LIGHT);
      
       if (myLightSensor == null){
        textLightSensor.setText("No Light Sensor!");
       }else{
        textLightSensor.setText(myLightSensor.getName());
        
        mySensorManager.registerListener(lightSensorEventListener,
          myLightSensor,
          SensorManager.SENSOR_DELAY_NORMAL);
       }
   }
  
   SensorEventListener lightSensorEventListener
    = new SensorEventListener(){

   @Override
   public void onAccuracyChanged(Sensor arg0, int arg1) {
    // TODO Auto-generated method stub
    
   }

   @Override
   public void onSensorChanged(SensorEvent arg0) {
    // TODO Auto-generated method stub
    if(arg0.sensor.getType()==Sensor.TYPE_LIGHT){
     textLightSensorData.setText("Light Sensor Date:"
       + String.valueOf(arg0.values[0]));
    }
   }};
}

And layout:

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
   android:orientation="vertical"
   android:layout_width="fill_parent"
   android:layout_height="fill_parent"
   >
<TextView 
   android:layout_width="fill_parent"
   android:layout_height="wrap_content"
   android:text="@string/hello"
   />
<TextView 
   android:id="@+id/lightsensor"
   android:layout_width="fill_parent"
   android:layout_height="wrap_content"
   />
<TextView 
   android:id="@+id/lightsensordata"
   android:layout_width="fill_parent"
   android:layout_height="wrap_content"
   />
</LinearLayout>

Satisfying depdencies when building from source

If a source package has a Make file with "make install" functionality, running the command "check install" will generate a pseudo package for you that will install all required dependencies and after building the package can be used to remove all dependencies. What a find!

Handy tips

I just realized that a good way to remember the tips and things I come across that I have no place to put them, yet I realize I will never remember them when I actually need to use them, is to create a blog. So here we are. (I am thinking of Linux stuff, but anything will work).