Embedded Files
What is Function ?
Function is a series of commands which performs particular activity in the script.
Uses of Functions ?
Code Reusability
Complexity of the script can be divided into smaller sections
Writing functions in the script will reduce the time
Syntax of Function:
Function name ()
{
Commands
}
Example1:
Write a script to print the "hello world" by using Function ?
#!/bin/bash
#script for priniting Hello world
Hello ()
{
echo "Hello World"
}
Hello
Output:
[vagrant@jhrk functions]$ sh basicfunexa1.sh
Hello World
Example2:
script for listing files with given extension ?
#! /bin/bash
#script for listing files with given extension
lsext ()
{
find -type -f -iname '*.' ${1} ' ' -exec ls -l {} \; ;
}
Output:
Example 3:
Script to execute a given Linux command on a group of files
Passing Parameters to Function
example 1:
Output:
Nested Functions
Nested Functions are the functions which can call themselves and other functions. A function which call itself is known as recursive function .
Syntax:
fun1 ()
{
commands
fun2 ()
{
commands
}
}
Example:
Output:
Function return value
Function return value
You cannot return an arbitrary result from a shell function. You can only return a status code which is an integer between 0 and 255. (While you can pass a larger value to return, it is truncated modulo 256.) The value must be 0 to indicate success and a different value to indicate failure; by convention you should stick to error codes between 1 and 125, as higher values have a special meaning (bad external command for 126 and 127, killed by a signal for higher values).
#!/bin/bash# This script will illustrate the use of return statement# It takes command line arguments as your name# choice() { echo "Is your name $* ?" while true do echo -n "Enter yes or no:" read x case "$x" in y | yes ) return 0;; n | no ) return 1;; * ) echo "Answer yes or no" esac done}# main begins here...echo "Original parameters are $*"if choice "$1"then echo "Hi $1, nice name"else echo "Never mind"fi
The execution of the above script as follows
Screenshot... Hari
:
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