Linux operating system shell and functions

definition of shell and function

1. Linux Shell functions

form a set of command sets or statements into an available block, These statement blocks are called functions.

2. composition of Shell functions

Functions Name: Function names, note that the function name in a script is unique, otherwise it will cause the calling function to be disorganized.

function Body: a collection of functions internal commands that implement a business function.

3. format of Shell function definition

function function name () # function can be omitted, note () inside without any parameters.

{

Command 1

Command 2

. . .

}

Examples of function use methods

1. function definition and reference instance one: The simplest definition and reference

[Email protected] myscript]$ sh func_1.sh

Walkthrough function Definition and Reference method :

Welcome,now time is Wed 16:01:58 CST 2015

Actual environment operation:

Execution Result:

2. function definition and reference instance two: passing parameters to a function walkthrough

passing arguments to a function is like using a special variable $1,$2...$9 in a generic script , after the function obtains the argument, it is best to reset the variable to save the argument within the function.

Program function: Pass a variable value to the function, perform the related operation on the value of the variable, and output the result.

[Email protected] myscript]$ sh func_2.sh

The method of passing the arguments inside the function (note the method of receiving the variable)

Number of arguments conforming to function requirements

10+90=100

Actual environment operation:

Execution Result:

3. function files and script files are not in the same file, how can I call this function?

program function: Enter the path of a file, and then print out the file's MD5 summary information.

[[email protected] myscript]$ Cat func_3.sh # function File

[[Email protected] myscript]$ SH func_call.sh # script file

Please enter a file name : test1.sh

Test1.sh 's MD5 Summary is : 5615ac3ce36ec58748a80649c3599d88 test1.sh

Please enter a file name : test2.sh

Test2.sh 's MD5 Summary is : 4446b536dff610ea440663147914c52b test2.sh

Please enter a file name : ttt.sh

Ttt.sh 's MD5 Summary is : 5615ac3ce36ec58748a80649c3599d88 ttt.sh

Notice how the function is imported:

. whitespace file name

Actual environment operation:

Execution Result:

Original link:http://www.maiziedu.com/wiki/linux/array/

Linux operating system shell and functions