BASH/C3/Advance-topics-in-a-function/English-timed

Time	Narration
00:01	Dear friends, welcome to the spoken tutorial onAdvance topics in a function .
00:08	In this tutorial, we will learn:
00:11	source command To put a function in the background
00:14	with the help of some examples.
00:18	To follow this tutorial, you should have knowledge of Shell Scripting in BASH.
00:24	If not, for relevant tutorials, please visit our website which is as shown. http://spoken-tutorial.org/What_is_a_Spoken_Tutorial
00:30	For this tutorial, I am using:
00:32	Ubuntu Linux 12.04 Operating System and
00:36	GNU BASH version 4.2
00:40	Please note, GNU Bash version 4 or above is recommended for practice.
00:46	source command is used to load a file into Shell script.
00:53	It reads and executes commands from that file.
00:58	It also imports code into the script.
01:01	This is useful when multiple scripts use a common data or a function library.
01:09	The syntax for source command is as follows-
01:12	source filename
01:15	source Path_to_file
01:18	souce filename arguments.
01:22	Let me open a file 'function dot sh'.
01:26	This is theshebang line.
01:29	source detail dot sh will load the file detail dot sh into function dot sh.
01:37	Let me open detail dot sh file.
01:41	I have a function machine.
01:44	Now, type inside the function-
01:47	echo "function machine is called in function dot sh file" .
01:52	Click on Save.
01:54	Now let us go back to function dot sh file.
01:59	Here, type: echo “Beginning of program”.
02:04	Click on Save.
02:06	Then type: machine echo “End of program”.
02:12	This will print the message “Beginning of program”.
02:16	machine is the function call.
02:19	And this will print the message End of program.
02:23	Note that machine is the function which we created in the detail dot sh file.
02:29	And we are calling the function, here, in function dot sh file.
02:34	Now click on Save.
02:36	Let us execute the program.
02:41	So, type on the terminal: chmod space plus (+) x space function dot sh
02:51	Press Enter.
02:53	Type: dot slash function dot sh
02:56	Press Enter.
02:59	The output is displayed.
03:02	Now let's move on to background function.
03:06	To run a process in the background, we use & (ampersand) at the end of a function call.
03:13	The shell forks a child process to run the command.
03:19	The forked process will have a job number and a PID (Process Identifier).
03:27	Let us understand this with the help of an example. I will open the file background dot sh.
03:35	This is the shebang line.
03:38	bg underscore function marks the beginning of the function.
03:44	The echo statement here displays the message "Inside bg_function”.
03:50	Next, we will use the find command to find all the dotmp3 files.
03:57	This statement will find all the files with the extension dot mp3.
04:03	It will do so in the current working directory.
04:07	Hyphen iname is used to ignore the case.
04:11	And the result is stored in myplaylist.txt.
04:16	Now, type: bg underscore function ampersand(&). This is the function call. '&'(Ampersand) puts 'bg_function' in the background.
04:28	Now click on Save.
04:31	Let us execute the program.
04:34	Come back to the terminal.
04:37	Type: chmod space plus x space background dot sh
04:45	Press Enter.Now, type: dot slash background dot sh
04:51	Press Enter.
04:53	Blank output indicates dot mp3 file is not present in current directory.
05:02	Now, come back to our program.
05:05	Type: echo (hyphen) -e "Process running in background are: backslash n" and jobs space hyphen l
05:19	Click on Save.
05:21	This echo statement will display the message “Process running in background are ”.
05:28	jobs space hyphen l lists the status of all background jobs.
05:34	Now come back to our terminal.
05:38	Now, type: dot slash background.sh.
05:42	Press Enter.
05:44	The output is shown.
05:48	Here, one within opening and closing square bracket is the job number.
05:53	3962 is the PID.
05:57	PID will vary accordingly.
06:01	If the function takes time to execute, it will run the process in the background
06:06	and we will see the status as "Running".
06:11	If the function gets executed before the script, we will see the status as "Done".
06:20	The output will vary from machine to machine.
06:23	This brings us to the end of this tutorial.
06:28	Let us summarize.In this tutorial, we learned:
06:32	* Source command
06:34	* To put a function in the background
06:36	with the help of some examples.
06:39	As an assignment:Write a function add to add two numbers and call the function in another file.
06:47	Watch the video available at the link shown below http://spoken-tutorial.org/What_is_a_Spoken_Tutorial
06:51	It summarizes the Spoken-Tutorial project.
06:55	If you do not have good bandwidth, you can download and watch it.
07:00	The Spoken Tutorial Project team: Conducts workshops using spoken tutorials. Gives certificates to those who pass an online test.
07:10	For more details, please write to contact@spoken-tutorial.org
07:18	Spoken Tutorial project is a part of the Talk to a Teacher project.
07:22	It is supported by the National Mission on Education through ICT, MHRD, Government of India.
07:30	More information on this mission is available at the link shown below. http://spoken-tutorial.org/NMEICT-Intro
07:36	The script has been contributed by FOSSEE and Spoken-Tutorial teams.
07:42	This is Ashwini from IIT Bombay. Thank you for joining.

Contributors and Content Editors

Pratik kamble, Sandhya.np14