Virtualization using Vagrant for Selenium Tests

Say goodbye to “works on my machine” bugs.

Nobody likes to release software on a Friday. What if something breaks over the weekend? There’s nothing like debugging an issue in production when you’re doing some day drinking at a BBQ.

But you have nothing to worry about, right? I mean, you tested the application and it worked on *your* machine. Too bad that’s never good enough. Have fun working this weekend.

If only you had automated tests for your application (across all of the browsers and all the platforms you cared about). Then you could rest easy this weekend and enjoy the festivities.

Creating a robust and scalable execution environment for automation tests is a very essential phase. In automated tests for web, we actually need to cover different browsers and platforms.

In this documentation, we are going to see how to run our selenium tests in a Linux box using vagrant.

Basically I have a selenium test that works fine when running in different browsers in my Windows host machine. But I want to make sure that it is running fine on the browsers in a Linux box too. Instead of creating an actual VM and running my tests, I am simply going to create a light weight portable Linux box and I am going to run my selenium tests from my windows host machine.

Also every time that you want to run your tests in your local machine, it opens the browser on top of the other windows, preventing you from doing something else. Unless you use Phantomjs or HTMLUnitDriver, it is not possible to run Chrome or Firefox hidden, without disturbing you on your work. Now using Vagrant and VirtualBox, you only need to start the VM, and all your tests will be run into the VM. You can continue developing in the meanwhile!

WHY VAGRANT?

Vagrant provides us easy to configure, reproducible, and portable work environments. Vagrant stands on top of VirtualBox, VMware and some other service providers. If you’re a developer, Vagrant will isolate dependencies and their configuration within a single disposable, consistent environment. If you’re a tester, Vagrant will help you to create light weight Virtual environments to run your tests against all the possible OS + Browser combinations.

Prerequisites:

  1. Download and install Oracle VM Virtualbox – https://www.virtualbox.org/wiki/Downloads
  2. Download and install Vagrant – http://www.vagrantup.com/downloads

From command line, type vagrant –v and make sure that you get the version number that you installed. Vagrant 1.7.21

Vagrant Boxes:

Boxes are the package format for Vagrant environments. A box can be used by anyone on any platform that Vagrant supports to bring up an identical working environment. The easiest way to use a box is to add a box from the publicly available catalog of Vagrant boxes for VirtualBox. We can also add and share our own customized boxes on this website.

I am going to use this box chef/ubuntu-14.04 – a standard Ubuntu 14.04 x64 base install.

Getting Started:

  1. Create a workspace directory to store the vagrant configuration file and shell scripts.

I have created “D:\Automation\Vagrant\Demo”

  1. From Command line go to your workspace and type vagrant init chef/ubuntu-14.04

2

  1. Make sure that the vagrant file is created in “D:\Automation\Vagrant\Demo”
  2. Run the command vagrant up

3If you are running this for first time, it may take some considerable amount of time to download the virtual box image and will put it under C:\Users\<username> \VirtualBox VMs\Demo_default_*

  1. Now the Ubuntu base image VM is up and running. Run the Command vagrant halt. This will power off the VM. Because we need to provision this VM with selenium related libraries, browsers and some utilities to run our selenium tests.
  2. Update the vagrant file in “D:\Automation\Vagrant\Demo” with the following content. Basically the default generated vagrant file has some lot of optional behaviors which are commented by default and you may enable it you need. But we require only the following content in a vagrant file.

 

Vagrant.configure(2) do |config|
   config.vm.box = "chef/ubuntu-14.04"
   config.vm.provision :shell, :path =&gt; "Provisioner.sh"
   config.vm.network :forwarded_port, guest:4444, host:4444
end

Basically what we are trying to do above is enabling port forwarding in the VM. Selenium server will use the 4444 port by default and we are forwarding that port from VM to host machine.

Also we are going to provision this VM using the “Provisioner.sh” shell script. Provisioners in Vagrant allow you to automatically install software, alter configurations, and more on the machine, as part of the vagrant up process. This is useful since boxes typically aren’t built perfectly for your use case. Of course, if you want to just use vagrant ssh and install the software by hand, that works. But by using the provisioning systems built-in to Vagrant, it automates the process so that it is repeatable. Most importantly, it requires no human interaction, so you can vagrant destroy and vagrant up and have a fully ready-to-go work environment with a single command.

Vagrant gives you multiple options for provisioning the machine, from simple shell scripts to more complex, industry-standard configuration management systems. If you’ve never used a configuration management system before, it is recommended you start with basic shell scripts for provisioning.

So to run a selenium test in a new plain OS, we need following things.

  • JDK/JRE – To run the selenium server.
  • Google chrome browser
  • ChromeDriver
  • Some utilities like ‘Unzip’ to extract the chromedriver zip file.
  • Selenium Standalone Server
  • Xvfbor X virtual framebuffer – To run tests in headless mode.

Xvfb is a display server implementing the X11 display server protocol. In contrast to other display servers, Xvfb performs all graphical operations in memory without showing any screen output. So actually when we run our tests in a VM box, we won’t be able to see any browser popping up. It means no GUI interactions are possible. So I am going to install all the above packages along with the dependencies using Provisioner.sh

  1. Create Provisioner.sh in the “D:\Automation\Vagrant\Demo” with the following content.

#!/usr/bin/env bash

# Set start time so we know how long the bootstrap takes

T="$(date +%s)"

#echo 'Updating'

sudo apt-get -y update

echo 'Installing Zip/Unzip'

sudo apt-get -y install zip unzip

echo 'Installing Google Chrome'

sudo apt-get -y install google-chrome-stable

wget https://dl.google.com/linux/direct/google-chrome-stable_current_amd64.deb

sudo dpkg -i google-chrome-stable_current_amd64.deb

sudo apt-get -y install -f

echo 'Installing Google XVFB'

sudo apt-get -y install xvfb

sudo apt-get -y install -f

echo 'Installing JRE'

sudo apt-get -y install default-jdk

sudo apt-get -y install -f

echo 'Downloading and Moving the ChromeDriver/Selenium Server to /usr/local/bin'

cd /tmp

wget "http://chromedriver.storage.googleapis.com/2.8/chromedriver_linux64.zip"

wget "https://selenium.googlecode.com/files/selenium-server-standalone-2.35.0.jar"

unzip chromedriver_linux64.zip

mv chromedriver /usr/local/bin

mv selenium-server-standalone-2.35.0.jar /usr/local/bin

export DISPLAY=:10

cd /vagrant

echo "Starting Xvfb ..."

Xvfb :10 -screen 0 1366x768x24 -ac &

echo "Starting Google Chrome ..."

google-chrome --remote-debugging-port=9222 &

echo "Starting Selenium ..."

cd /usr/local/bin

java -jar selenium-server-standalone-2.35.0.jar

# Print how long the bootstrap script took to run

T="$(($(date +%s)-T))"

echo "Time bootstrap took: ${T} seconds"

  1. Run vagrant up –provision this will start the VM and then install the list of packages that we have added in the sh and also it will start the selenium server in 4444 port.

4

You can see this by navigating to http://localhost:4444/wd/hub/static/resource/hub.html from your windows host machine [As we have port forwarded].

Now run the following selenium test from any of your favorite IDE.

package test;

import java.net.URL;
import java.util.concurrent.TimeUnit;
import org.openqa.selenium.WebDriver;
import org.openqa.selenium.remote.DesiredCapabilities;
import org.openqa.selenium.remote.RemoteWebDriver;

public class HeadlessSession {	  
	  public static void main(String args[]) throws InterruptedException, Exception {	  
		  HeadlessSession.HeadlessSessionId();
	  }
	  
	  public static void HeadlessSessionId() throws Exception {
               DesiredCapabilities capabilities = new DesiredCapabilities();
	       capabilities.setBrowserName("chrome");
	       WebDriver driver = new RemoteWebDriver(new URL("http://localhost:4444/wd/hub"), capabilities);	  
		  try {				
			    String baseUrl = "http://www.google.com";
			    driver.manage().timeouts().implicitlyWait(60, TimeUnit.SECONDS);
			    driver.get(baseUrl);
			    System.out.println("Title : " + driver.getTitle());
			    String browserName = capabilities.getBrowserName().toLowerCase();
			    System.out.println("Browser : " + browserName);
		  } catch (Exception e) {
			  System.out.println(e.getMessage());
		  }
		  finally {
		    driver.close();
		    driver.quit();
		  }
	  }
}

That’s it. Now you have successfully ran your tests in Chrome browser in a Linux box from your windows host machine.

Useful Vagrant Commands:

Command Action
vagrant up Power on the VM
vagrant halt Power off the VM
vagrant reload Restart
vagrant suspend Saving the VM state and sleep
vagrant resume Resuming the suspended VM
vagrant provision Provision the VM by running the Provisioner.sh or any other shell script mentioned in the vagrant file.
vagrant up –provision Power on with provision
vagrant reload –provision Restart with provision

Pros:

  1. Easy to setup and maintain.
  2. It’s free.
  3. Able to clone the production/staging environment for our test execution.
  4. Light weight and portable.
  5. Support to provisioning scripts like Shell, Chef, and Puppet.
  6. Simple command line based workflow.
  7. Goodbye to ‘Works on my machine’ bugs.
  8. For selenium, you can able to run headless tests on your favorite browser.
  9. Create and destroy the VMs as needed.
  10. It works on all major platforms.
  11. We can also use Selenium Grid along with vagrant to run tests parallely across different VM’s.

Cons:

  1. Base boxes for your choice of operating system might not be readily available.
  2. Little bit of time consuming to make vagrant VM up and running.
  3. Taking lot of time when provisioning the VM box. To avoid this, create your own base box by installing all the required dependencies by manually SSH into it and then use provisioning script only for starting the Selenium Server.
  4. Light weight. But looks fatty when considering the alternatives like Docker.
  5. It requires you to have a hard drive file that can be huge and it takes a lot of RAM.

SoapUI Get SessionID

The whole purpose is, I have to automate testing for some Secured API’s, which need Session Id of my application to send request and to receive expected response.

I am using Soap-UI for my API Testing.

Initially I thought of using SoapUI to achieve the same. But my application uses SAML requests and do lot of redirection before getting into the Login Page.

So my alternative workaround is to go for the some other frameworks to fetch this session Id.

I have already discussed the same in the following post.

https://linkeshkannavelu.com/2014/02/13/selenium-webdriver-get-sessionid-from-a-web-application/

But in the above mentioned Post, I was using the FirefoxDriver. This will trigger the Firefox browser all the time and then it will fetch me the session information.

I somehow felt inside that this is not a proper workaround and always searched for the better alternative solutions.

Now I just want to let you know something that I have tried earlier to get the Session Cookie in headless mode without a browser.

Earlier I have tried out a solution to use the HTMLUnitDriver instead of FirefoxDriver to get the session information with a headless browser.

Initially I got lot of exceptions with earlier version of selenium standalone server.

But this works perfectly with the latest version of selenium. I really don’t know why.

Now the updated script will run in daemon mode and will fetch you the session id without a browser.

Obviously if you use HTMLUnitDriver, it will always throw severe bunch of warnings that you may not need.

All we need is just the session information of the application.

So, somehow I found out a way to turn off the HTMLUnitDriver logging just to avoid these bunch of severe warnings and unwanted information.

The following method will get you the SessionId of a web application.

I just pasted the method here. Of course you guyz may need to do some modification based on your needs.

You need to add the latest version of Selenium-Standalone-Server in your class path for this method to work.

public static void HeadlessSessionId() throws Exception {
		  WebDriver driver = new HtmlUnitDriver(true);
		  
		  try {		  	
			  	LogFactory.getFactory().setAttribute("org.apache.commons.logging.Log", "org.apache.commons.logging.impl.NoOpLog");
			    java.util.logging.Logger.getLogger("com.gargoylesoftware.htmlunit").setLevel(Level.OFF);
			    java.util.logging.Logger.getLogger("org.apache.commons.httpclient").setLevel(Level.OFF);
				String domainString = ServiceEndPoint;		
			    String baseUrl = domainString;
			    driver.manage().timeouts().implicitlyWait(60, TimeUnit.SECONDS);
			    driver.get(baseUrl + "/Demo/");			    
			    driver.findElement(By.id("username")).clear();
			    driver.findElement(By.id("username")).sendKeys("UserName");
			    driver.findElement(By.id("password")).clear();
			    driver.findElement(By.id("password")).sendKeys("PassWord");
			    driver.findElement(By.cssSelector("input.primary.btn")).click();			    		    
			    String SessionId = driver.manage().getCookieNamed("sessionId").toString();			    
			    domainString = domainString.replaceAll("http://", "domain=");
			    String SessionID = ((SessionId).replaceAll("path=/;", " ")).replaceAll(domainString, "").replaceAll("Cookie: ", ""); 
			    Cookie = SessionID;
			    System.out.println(SessionID);
		  }
		  finally {
		    driver.close();
		  }
	  }

So That’s it. We have the session information of our application in Hand. Now how we are going to integrate this with our SoapUI?

During the development phase/when running my tests manually from SoapUI GUI, I have a project level property defined in SoapUI called “Cookie”.

And I will manually replace that project property with the session information that I got from my selenium script.

Later I will use this Project level Property in my SoapUI test cases/ test steps.

But as a automation engineer, at some point, I may want to add these tests in my Continuous Integration Server to run these tests on a nightly Builds.

At that time, there should not be any manual intervention in my automated tests.

So lets see how I actually integrated the session that I am getting it from Selenium with SoapUI.

All we need to do is simple.

Instead of printing the session Id, write it in a property file. I used to write this session Id in “SoapUIProjectProerties.props”

Export the entire Java project into a runnable Jar file.

If you are using any IDE like Eclipse, it is not that difficult task. Then create a Batch file that will do the following steps.

1. First run the Jar File and this will write the SessionID into that Property File.
2. Use SoapUI TestRunner Batch from Command Line and Specify it to load the Properties from the “SoapUIProjectProerties.props”

@ECHO OFF
SET SOAPUI_TEST_RUNNER="C:\Program Files (x86)\SmartBear\SoapUI-5.0.0\bin\"
java -jar HeadlessSessionId.jar
%SOAPUI_TEST_RUNNER%testrunner.bat -sTestSuiteName -r -a -j -f"Reports" -i Project-Name.xml 
-Dsoapui.properties.CommonAuthWebService=SoapUIProjectProerties.props

Now during the runtime, the session Id property defined in the property file will be used by SoapUI for hitting secured API’s.

I hope this solution might be helpful for your when automating secured API’s which need session Id.

My Colleague is working on another interesting solution to rewrite the whole Java program as a ‘Groovy Test Script’ in SoapUI.

I will let you know if that works. Thanks.

RoboCopy in Windows

Robocopy (Robust File Copy) is a command-line file copy utility.

To use this utility simple type the following command in the command prompt.

Robocopy C:\SourceFolder C:\DestinationFolder

This will copy the contents of the source folder to destination folder.

To copy all contents including empty directories of SourceFolder to DestinationFolder:
Robocopy C:\SourceFolder C:\DestDir /E 

Redirecting Logs in Windows Batch File to a Log File

If you simply want to redirect all your logs to a Log.txt file, use the following script and save it as a ".bat" file.
@echo off
SET LOGFILE="Log.txt"
call :Logit >> %LOGFILE%
exit /b 0
:Logit
ECHO ########This is a Log######################################

Now Run the batch file that you have created. You will see the logs in a Log.txt file.

If you want to Create the Log file with date time stamp, then use the following script and save it as a batch file.

 @echo off 
SET LOGFILE="LOG-%date%-%time:~0,2%-%time:~3,2%-%time:~6,2%.txt" 
call :Logit >> %LOGFILE% 
exit /b 0 
:Logit 
ECHO ########This is a Log######################################

This will create the LOG-YYYY-MM-DD-HH-MM-SS.txt file for you.

UNIX BASICS

UNIX BASICS

Main features of unix :

Multi user – More than one user can use the machine

Multitasking– More than one program can be run at a time.

Portability – This means the operating system can be easily converted to run on different browsers.


Commands

ls

when invoked without any arguments, lists the files in the current working directory. A directory that is not the current working directory can be specified and ls will list the files there. The user also may specify any list of files and directories. In this case, all files and all contents of specified directories will be listed.

Files whose names start with “.” are not listed, unless the -a flag is specified or the files are specified explicitly.

Without options, ls displays files in a bare format. This bare format however makes it difficult to establish the type, permissions, and size of the files. The most common options to reveal this information or change the list of files are:

-l long format, displaying Unix file type, permissions, number of hard links, owner, group, size, date, and filename

-F appends a character revealing the nature of a file, for example, * for an executable, or / for a directory. Regular files have no suffix.

-a lists all files in the given directory, including those whose names start with “.” By default, these files are excluded from the list.

-R recursively lists subdirectories. The command ls -R / would therefore list all files.



cd

Is a command line command used to change the current working directory in the Unix and DOS operating systems. It is also available for use in Unix shell scripts or DOS batch files. cd is frequently included built into certain shells such as the Bourne shell, tcsh, bash (where it calls the chdir() POSIX C function) and in DOS’s COMMAND.COM.

A directory is a logical section of a filesystem used to hold files. Directories may also contain other directories. The cd command can be used to change into a subdirectory, move back into the parent directory, move all the way back to the root (/ in UNIX, \ in DOS) or move to any given directory.

pwd

command (print working directory) is used to print the name of current working directory from a computer’s command-line interface. If the shell prompt does not already show this, the user can use this command to find their place in the directory tree. This command is found in the Unix family of operating systems and other flavors as well. The DOS equivalent is “CD” with no arguments.

It is a command which is sometimes included built into certain shells such as sh, and bash. It can be implemented easily with the POSIX C functions getcwd() and/or getwd().

Example:

$ pwd

/home/foobar


mkdir

command in the Unix operating system is used to make a new Directory. Normal usage is as straightforward as follows:

mkdir name_of_directory

Where name_of_directory is the name of the directory one wants to create. When typed as above (ie. normal usage), the new directory would be created within the current directory.

rm (short for remove)

is a Unix command used to delete files from a filesystem. Common options that rm accepts include:

-r, which processes subdirectories recursively

-i, which asks for every deletion to be confirmed

-f, which ignores non-existent files and overrides any confirmation prompts (“force”)

rm is often aliased to “rm -i” so as to avoid accidental deletion of files. If a user still wishes to delete a large number of files without confirmation, they can manually cancel out the -i argument by adding the -f option.

rm -rf” (variously, “rm -rf /”, “rm -rf *”, and others) is frequently used in jokes and anecdotes about Unix disasters. The “rm -rf /” variant of the command, if run by an administrator, would cause the contents of every mounted disk on the computer to be deleted.

rmdir

is a command which will remove an empty directory on a Unix-system. It cannot be capitalized. Normal usage is straightforward where one types:

rmdir name_of_directory

Where name_of_directory corresponds with the name of the directory one wishes to delete. There are options to this command such as -p which removes parent directories if they are also empty.

For example:

rmdir –p foo/bar/baz

Will first remove baz/, then bar/ and finally foo/ thus removing the entire directory tree specified in the command argument.

Often rmdir will not remove a directory if there is still files present in the directory. To force the removal of the directory even if files are present usually the -rf flag can be used. For example:

rmdir -Rf for/bar/baz



cp

is the command entered in a Unix shell to copy a file from one place to another, possibly on a different filesystem. The original file remains unchanged, and the new file may have the same or a different name.

To Copy a File to another File

cp [ -f ] [ -h ] [ -i ] [ -p ][ — ] SourceFile TargetFile

To Copy a File to a Directory

cp [ -f ] [ -h ] [ -i ] [ -p ] [ -r | -R ] [ — ] SourceFile … TargetDirectory

To Copy a Directory to a Directory

cp [ -f ] [ -h ] [ -i ] [ -p ] [ — ] { -r | -R } SourceDirectory … TargetDirectory

-f (force) – specifies removal of the target file if it cannot be opened for write operations. The removal precedes any copying performed by the cp command.

-h – makes the cp command copy symbolic links. The default is to follow symbolic links, that is, to copy files to which symbolic links point.

-i (interactive) – prompts you with the name of a file to be overwritten. This occurs if the TargetDirectory or TargetFile parameter contains a file with the same name as a file specified in the SourceFile or SourceDirectory parameter. If you enter y or the locale’s equivalent of y, the cp command continues. Any other answer prevents the cp command from overwriting the file.

-p (preserve) – duplicates the following characteristics of each SourceFile/SourceDirectory in the corresponding TargetFile and/or TargetDirectory:

Examples

To make a copy of a file in the current directory, enter:

cp prog.c prog.bak

This copies prog.c to prog.bak. If the prog.bak file does not already exist, the cp command creates it. If it does exist, the cp command replaces it with a copy of the prog.c file.

To copy a file in your current directory into another directory, enter:

cp jones /home/nick/clients

This copies the jones file to /home/nick/clients/jones.

To copy a file to a new file and preserve the modification date, time, and access control list associated with the source file, enter:

cp -p smith smith.jr

This copies the smith file to the smith.jr file. Instead of creating the file with the current date and time stamp, the system gives the smith.jr file the same date and time as the smith file. The smith.jr file also inherits the smith file’s access control protection.

To copy all the files in a directory to a new directory, enter:

cp /home/janet/clients/* /home/nick/customers

This copies only the files in the clients directory to the customers directory.

To copy a directory, including all its files and subdirectories, to another directory, enter:

cp -R /home/nick/clients /home/nick/customers

This copies the clients directory, including all its files, subdirectories, and the files in those subdirectories, to the customers/clients directory.

To copy a specific set of files to another directory, enter:

cp jones lewis smith /home/nick/clients

This copies the jones, lewis, and smith files in your current working directory to the /home/nick/clients directory.

To use pattern-matching characters to copy files, enter:

cp programs/*.c .

This copies the files in the programs directory that end with .c to the current directory, signified by the single . (dot). You must type a space between the c and the final dot.


find


program is a search utility, mostly found on Unix-like platforms. It searches through a directory tree of a filesystem, locating files based on some user-specified criteria. By default, find returns all files below the current working directory. Further, find allows the user to specify an action to be taken on each matched file. Thus, it is an extremely powerful program for applying actions to many files. It also supports regexp matching.


Examples

From current directory

find . -name my\*

This searches in the current directory (represented by a period) and below it, for files and directories with names starting with my. The backslash before the star is needed to avoid the shell expansion. Without the backslash, the shell would replace my* with the list of files whose names begin with my in the current directory. An alternative is to enclose the the arguments in quotes: find . -name “my*”

Files only

find . -name “my*” -type f

This limits the results of the above search to only regular files, therefore excluding directories, special files, pipes, symbolic links, etc. my* is enclosed in quotes as otherwise the shell would replace it with the list of files in the current directory starting with my

Commands

The previous examples created listings of results because, by default, find executes the ‘-print’ action. (Note that early versions of the find command had no default action at all; therefore the resulting list of files would be discarded, to the bewilderment of naïve users.)

find . -name “my*” -type f -ls

This prints an extended file information.

Search all directories

find / -name “myfile” -type f -print

This searches every file on the computer for a file with the name myfile. It is generally not a good idea to look for data files this way. This can take a considerable amount of time, so it is best to specify the directory more precisely.

Specify a directory

find /home/brian -name “myfile” -type f -print

This searches for files named myfile in the /home/brian directory, which is the home directory for the user brian. You should always specify the directory to the deepest level you can remember.

Find any one of differently named files

find . ( -name “*jsp” -or -name “*java” ) -type f -ls

This prints extended information on any file whose name ends with either ‘jsp’ or ‘java’. Note that the parentheses are required. Also note that the operator “or” can be abbreviated as “o”. The “and” operator is assumed where no operator is given. In many shells the parentheses must be escaped with a backslash, “\(” and “\)”, to prevent them from being interpreted as special shell characters.

touch

is a program on Unix and Unix-like systems used to change a file’s date- and time-stamp. It can also be used to create an empty file. The command-syntax is:

touch [options]

If the file exists, its access and modification time-stamps are set to the system’s current date and time, as if the file had been changed. To touch a file simulates a change to the file. If the file does not exist, an empty file of that name is created with its access and modification time-stamps set to the system’s current date and time. If no file path is specified, the current directory is assumed.

touch can be invoked with options to change its behaviour, which may vary from one Unix to another. One option makes it possible to set the file’s time-stamp to something other than the current system date and time, but this action is normally restricted to the owner of the file or the system’s superuser.

echo

is a command in Unix (and by extension, its descendants, such as Linux) and MS-DOS that places a string on the terminal. It is typically used in shell scripts and batch programs to output status text to the screen or a file.

$ echo This is a test.

This is a test.

$ echo “This is a test.” > ./test.txt

$ cat ./test.txt

This is a test.


cat

program concatenates the contents of files, reading from a list of files and/or standard input in sequence and writing their contents in order to standard output. cat takes the list of files as arguments but also interprets the argument “-” as standard input.

Example: cat filename

who

The Unix command who displays a list of users who are currently logged into a computer. The command accepts various options that vary by system to further specify the information that is returned, such as the length of time a particular user has been connected or what pseudo-teletype a user is connected to. The who command is related to the command w, which provides the same information but also displays additional data and statistics.

Example output

user19 pts/35 Apr 18 08:40 (localhost)

user28 pts/27 Apr 18 09:50 (localhost)



du (abbreviated from disk usage)

is a Unix computer program to display the amount of disk space used under a particular directory or files on a file system.

du counts the disk space by walking the directory tree. As such, the amount of space on a file system shown by du may vary from that shown by df if files have been deleted but their blocks not yet freed.

In Linux, it is a part of the GNU Coreutils package.

The du utility first appeared in version 1 of AT&T UNIX.

Example

The -k flag will show the sizes in 1K blocks, rather than the default of 512 byte blocks.

$du -k /seclog

4 /seclog/lost+found

132 /seclog/backup/aix7

136 /seclog/backup

44044 /seclog/temp

439264 /seclog


We will discuss more advanced commands in the next article.