Download to read offline
![● But if you are looking of the subdomains of facebook you need to
retype the command as following:
$ cat index.html | grep -i -o “[a-z0-9]*.facebook.com”
Shell Commands : wget](https://image.slidesharecdn.com/module2-250615182747-bb5bbe36/75/Basics-of-Bash-Scripting-OVUGUFYYGFCGHKJJJC-31-2048.jpg)
![● As you can see in the previous slide, there are repeated outcomes we
need to eliminate them
● To do so and get only the unique values, use the sort function as
following:
$ cat index.html | grep -i -o “[a-z0-9]*.facebook.com” | sort -u
Shell Commands : sort](https://image.slidesharecdn.com/module2-250615182747-bb5bbe36/75/Basics-of-Bash-Scripting-OVUGUFYYGFCGHKJJJC-32-2048.jpg)
![● Now suppose you only need the first part of the domain and ignore the
.facebook.com
● To do so, use cut function with the delimiter as following:
$ cat index.html | grep -i -o “[a-z0-9]*.facebook.com” | sort -u | cut -d “.” -f1
Shell Commands : cut](https://image.slidesharecdn.com/module2-250615182747-bb5bbe36/75/Basics-of-Bash-Scripting-OVUGUFYYGFCGHKJJJC-33-2048.jpg)
![● But if you are looking of the subdomains of facebook you need to
retype the command as following:
$ cat index.html | grep -i -o “[a-z0-9]*.facebook.com”
Shell Commands : wget](https://crownmelresort.com/image.slidesharecdn.com/module2-250615182747-bb5bbe36/75/Basics-of-Bash-Scripting-OVUGUFYYGFCGHKJJJC-31-2048.jpg)
![● As you can see in the previous slide, there are repeated outcomes we
need to eliminate them
● To do so and get only the unique values, use the sort function as
following:
$ cat index.html | grep -i -o “[a-z0-9]*.facebook.com” | sort -u
Shell Commands : sort](https://crownmelresort.com/image.slidesharecdn.com/module2-250615182747-bb5bbe36/75/Basics-of-Bash-Scripting-OVUGUFYYGFCGHKJJJC-32-2048.jpg)
![● Now suppose you only need the first part of the domain and ignore the
.facebook.com
● To do so, use cut function with the delimiter as following:
$ cat index.html | grep -i -o “[a-z0-9]*.facebook.com” | sort -u | cut -d “.” -f1
Shell Commands : cut](https://crownmelresort.com/image.slidesharecdn.com/module2-250615182747-bb5bbe36/75/Basics-of-Bash-Scripting-OVUGUFYYGFCGHKJJJC-33-2048.jpg)
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Basics of Bash Scripting OVUGUFYYGFCGHKJJJC
- 1. 1. Part 1:Shell in Linux 2. Part2: Shell commands 3. Part3: additional commands 4. Part4: Processes 5. Part5: bash code AGENDA
- 2. Shell The power ofLinux 01
- 3. ● Simply theshell is a program that takes commands from the user and gives them to the operating system to perform. ● In other words we can say that, shell is the layer of programming that understands and executes the commands a user enters. ● In some systems, the shell is called a command interpreter. Shell in Linux
- 4.
- 5. Linux User Kernel SHELL TheProgramming interface/Interpreter Commands Execute the CMD
- 6. Shell in Linux ●There are different flavors of a shell, just as there are different flavors of operating systems. ● Each flavor of shell has its own set of recognized commands and functions. ● On most Linux systems a program called bash (which stands for Bourne Again SHell, an enhanced version of the original Unix shell) program sh (written by Steve Bourne) acts as the shell program. ● Besides them, there are other shell programs available for Linux systems. These include: ksh, tcsh and zsh.
- 7. User Application Shell Low levelutilities and modules Kernel
- 8. ● Terminal isa program that opens a window and lets you interact with the shell. ● There are a bunch of different terminal emulators we can use. ● These might include: ○ gnome-terminal ○ Konsole ○ Xterm ○ Rxvt ○ Kvt ○ nxterm ○ eterm. Terminal
- 9. User Application Shell Low levelutilities and modules Kernel Terminal
- 10. Shell Commands Enjoy thepower of shell ! 02
- 11. ● Shell ispowerful program that allow you to perform a lot of commands to save your effort, time and many more ● Some of commands we are going to discuss are: ○ Echo ○ > and >> ○ grep ○ Piping “|” ○ Head ○ Tail ○ ; and && ○ Locate ○ The & Shell Commands
- 12. ● Echo commandallows you to print out the string or other on the terminal ● $ echo “Hello .. This is Banhawi” Shell Commands : Echo
- 13. ● These twosymbols “>” and “>>” let you save the command output into a file ● The difference between them is: ○ “>” will delete whatever pre-stored in the file and save the new output into this file ○ “>>” will abend over whatever pre-stored in the file Shell Commands : > and >>
- 16. ● Grep commandlet you filter or search for specific word inside a file ● Suppose you listed /etc subfile and subdirectories and saves it into Test.txt on the Desktop ● This file contains a huge files and to search for specific file you need to use “grep” command Shell Commands : grep
- 18. ● Piping “|”let you to do another command after the first command be successfully performed. ● So if you need to list the subdirectories and store it after you can do it using this command too. ● Thus we can say that piping command always related to the previous command, it will perform an additional command on the output of the first command Shell Commands : piping “|”
- 20. ● Head commandlet you view the top lines of any file. ● You can specify number of lines you need to view using the argument -n Shell Commands : head
- 21. ● Tail commandlet you view the bottom lines of any file. ● You can specify number of lines you need to view using the argument -n Shell Commands : tail
- 22. ● The semicolon“;” and “&&” allow you to do two or more different command in the same line one after one. Shell Commands : “;” and &&
- 23. ● To searchfor some file or directory, locate is one of the command you can use to search for this file or directory. ● As we see, we tried to search for the file “rockyou.txt” in the system and the location is: /usr/share/wordlist/ Shell Commands : locate
- 24. ● Now supposeyou need to perform a command however you know that this command will take a lot of time to be executed. ● The proper way to do this is to run this command in the background and here come the power of “&” ● & let you perform your command in the background while you perform other tasks. ● All you need to do is to type your command and at the very end just type “&” Shell Commands : &
- 25. ● As youcan see below after typing the command, a new process initiated with PID: 2542 to perform this task in the background ● After the task has been finished the terminal notified you with that this task has been done successfully ● If you need to see the live process that take a place right now only you need to type $ top Shell Commands : &
- 26.
- 27. ● Now weare going to discuss more commands to use. ● Some of commands we are going to discuss are: ○ wget ○ Sort ○ Cut Shell Commands
- 28. ● Wget letyou download the index page of any website. ● For example, let’s wget the facebook page Shell Commands : wget
- 29. ● Now ifyou cat the index file that has just downloaded you will see a huge file Shell Commands : wget
- 30. ● Let usgrep it to get only facebook.com ● To do it in effective way just type: $ cat index.html | grep -i -o “facebook.com” ○ -i >> to ignore the case sensitivity ○ -o >> to restrict the output on “facebook.com” only Shell Commands : wget
- 31. ● But ifyou are looking of the subdomains of facebook you need to retype the command as following: $ cat index.html | grep -i -o “[a-z0-9]*.facebook.com” Shell Commands : wget
- 32. ● As youcan see in the previous slide, there are repeated outcomes we need to eliminate them ● To do so and get only the unique values, use the sort function as following: $ cat index.html | grep -i -o “[a-z0-9]*.facebook.com” | sort -u Shell Commands : sort
- 33. ● Now supposeyou only need the first part of the domain and ignore the .facebook.com ● To do so, use cut function with the delimiter as following: $ cat index.html | grep -i -o “[a-z0-9]*.facebook.com” | sort -u | cut -d “.” -f1 Shell Commands : cut
- 34. Processes What is doingbehind ! 04
- 35. More Commands ● Processesin linux is something similar to the task manager in Windows. ● It shows you the process running in the background with more extra information ● A lot of commands used for this task: ○ Ps ○ Ps -aux ○ Top ○ htop
- 36.
- 37. Bash Scripting ● Inbash scripting you can perform all of the previous tasks and save them as sh or bash file to be executed automatically once needed. ● Let us try to make our examples ...