Difference between revisions of "BASH/C3/Advance-topics-in-a-function/English-timed"

| Dear friends, Welcome to the spoken tutorial on'''Advance topics in a function '''

| In this tutorial, we will learn

| '''Source '''command

| To put a function in the '''background'''

| With the help of some examples.  

| To follow this tutorial you should have knowledge of '''Shell Scripting''' in''' BASH.'''

|If not, for relevant tutorials, please visit our website which is as shown '''http://spoken-tutorial.org/What\_is\_a\_Spoken\_Tutorial'''

| For this tutorial I am using

|'''GNU BASH''' version 4.2

| '''Source '''command is used to load a file into '''Shell '''script.

| It reads and execute commands from that file.

| It also imports code into the script.  

| This is useful when multiple scripts use a common data or a function library.

| The syntax for '''Source command''' is as follows.

|'''souce filename  arguments'''

| Let me open a file ''''function dot sh''''.

|'''Source detail dot sh''' will load the file '''detail dot sh '''into''' function dot sh '''

|I have a '''function''' '''machin'''.

|Now type inside the function,

|'''echo '"function machine''' is called in '''function dot sh file"'

|Here type '''echo''' '''“Beginning of program”'''

|Click on''' Save'''

|Then type  '''machine''' '''echo''' '''“End of program”'''

| This will print the message '''“Beginning of program”'''

| And this will print the message '''End of program'''

|And we are calling the '''function''' here in '''function dot sh''' file.

| Let us execute the program.

| So type on the '''terminal''' '''chmod space  plus (+) x space function dot sh'''

| Press '''Enter'''

| Type '''dot slash function dot sh'''

| The output is displayed

| To run a process in the background, we use '''&''' (ampersand)''' at the end of a '''function call.'''

| The '''shell''' forks a '''child process''' to run the command.  

|The forked process will have a '''job number''' and a '''PID (Process IDentifier)'''

| Let us understand this with the help of an example. I will open the file '''background dot sh'''

| The '''echo statement''' here displays the message '''"Inside bg_function”'''

| Next, we will use the '''find command '''to find all the dot'''mp3 '''files.

| This statement will find all the files with the extension '''dot mp3'''

| It will do so in the current working directory.

| Now type '''bg underscore function ampersand(&)''' This is the '''function call.''' '''&(Ampersand)''' puts ''''bg_function'''' in the background.

| Let us execute the program.

| Type '''chmod space plus x space background dot sh'''

|Now type '''dot slash background dot sh'''

|Type '''echo (hyphen) -e "'Process runing in background are  slash n'" ''' and '''jobs space hyphen l'''

|Click on''' Save'''

| This '''echo statement''' will displays the message “'''Process runing in background are ”'''

|Now type ''' dot slash background.sh'''

| The output is shown.

|If the function takes time to execute, it will run in the background.

|If the function gets executed before the script, we will see the status as '''Done'''

|The output will vary from machine to machine.

|Let us Summarise.  

|In this tutorial we learnt

| '''Source '''command

| To put a function in the '''background'''

| With the help of some examples  

| Watch the video available at the link shown below http://spoken-tutorial.org/What\_is\_a\_Spoken\_Tutorial

|It summarises the Spoken Tutorial project.

| The Spoken Tutorial Project Team .Conducts workshops using spoken tutorials. Gives certificates to those who pass an online test

| Spoken Tutorial Project is a part of the Talk to a Teacher project.

| More information on this Mission is available at the link shown below http://spoken-tutorial.org\NMEICT-Intro