Linux Learning -10-Learning shell scripts

[Email protected] ~]# mkdir scripts; CD scripts

[Email protected] scripts]# VI sh01.sh

#!/bin/bash declaring shell names

# program: Description of Procedure Content

# This program shows the "Hello world!" in the Your screen.

# History:

# 2005/08/23 Vbird First release path=/bin:/sbin:/usr/bin:/usr/sbin:/usr/local/bin:/usr/local/sbin:~/bin main environment variable declaration

Export PATH

Echo-e "Hello world! \a \ n "Main program section

Exit 0 Execution Result return value

Execution: chmod a+x sh01.sh;./sh01.sh

Interactive scripting

[Email protected] scripts]# VI sh02.sh

#!/bin/bash

# program:

# User inputs his first name and last name. Program shows he full name.

# History:

# 2005/08/23 Vbird First release Path=/bin:/sbin:/usr/bin:/usr/sbin:/usr/local/bin:/usr/local/sbin:~/bin

Export PATH

Read-p "Please input your first name:" FirstName # Prompts the user to enter

Read-p "Please input your last name:" LastName # Prompts the user to enter

Echo-e "\nyour full name is: $firstname $lastname" # Results from Screen output

Change with date

[Email protected] scripts]# VI sh03.sh

#!/bin/bash

# program:

# program creates three files, which named by user ' s input

# and Date command.

# History:

# 2005/08/23 Vbird First release Path=/bin:/sbin:/usr/bin:/usr/sbin:/usr/local/bin:/usr/local/sbin:~/bin

Export PATH

# 1. Let the user enter the file name, and get fileuser this variable;

Echo-e "I'll use ' touch ' command to create 3 files." # Display information purely

Read-p "Please input your filename:" Fileuser # Prompts the user to enter

# 2. In order to avoid the user arbitrarily press Enter, the use of variable function analysis file name is set?

filename=${fileuser:-"FileName"} # starts to determine if there is a profile name

# 3. Start using the date command to get the required file name;

date1=$ (Date--date= ' 2 days ago ' +%y%m%d) # Date of the previous two day

date2=$ (Date--date= ' 1 days ago ' +%y%m%d) # Date of the day before

date3=$ (Date +%y%m%d) # Today's date

FILE1=${FILENAME}${DATE1} # Bottom three lines in config file name

FILE2=${FILENAME}${DATE2}

File3=${filename}${date3}

# 4. Create a file name!

Touch "$file 1" # Bottom three lines in creating the file

Touch "$file 2"

Touch "$file 3"

Numeric operations

[Email protected] scripts]# VI sh04.sh

#!/bin/bash

# program:

# User inputs 2 integer numbers; Program would cross these and numbers.

# History:

# 2005/08/23 Vbird First release Path=/bin:/sbin:/usr/bin:/usr/sbin:/usr/local/bin:/usr/local/sbin:~/bin

Export PATH

ECHO-E "You should input 2 numbers, I'll cross them! \ n "

Read-p "First Number:" Firstnu

Read-p "second number:" Secnu

total=$ (($FIRSTNU * $secnu))

Echo-e "\nthe result of $firstnu x $SECNU is ==> $total"

[[email protected] scripts]# echo $ ((13% 3))

1

Test function

TEST-E/dmtsai && echo "Exist" | | echo "not exist"

P453

# 1. Let the user enter a file name and determine if the user actually has an input string?

ECHO-E "Please input a filename, I'll check the filename ' s type and \

Permission. \ n "

Read-p "Input a filename:" filename

Test-z $filename && echo "You must input a filename." && exit 0

# 2. Determine if the file exists? Show message and end script if not present

Test! -E $filename && echo "The filename ' $filename ' do not exist ' && exit 0

# 3. Start judging file types and properties

Test-f $filename && filetype= "Regulare file"

test-d $filename && filetype= "directory"

Test-r $filename && perm= "readable"

Test-w $filename && perm= "$perm writable"

Test-x $filename && perm= "$perm executable"

# 4. Start outputting information!

echo "The filename: $filename is a $filetype"

echo "and the permissions are: $perm"

Using judgment symbols []

[-"$HOME"-==-"$MAIL"-]

[To add a space]

Read-p "Please input (y/n):" yn

["$yn" = = "Y"-o "$yn" = = "Y"] && echo "OK, continue" && exit 0

["$yn" = = "n"-o "$yn" = = "n"] && echo "Oh, interrupt!" && exit 0

echo "I don ' t know your choice is" && exit 0

Default variable $ P457

Shift offset Variable

Conditional judgement Type If...then

If [conditional judgment]; Then when the conditional judgment is established, the instruction work content can be carried out;

Fi <== The IF in turn, it becomes fi! End the IF idea!

Multi-criteria

&& representative and;

|| represent or;

The last example changes to a single condition judgment

Read-p "Please input (y/n):" yn

If ["$yn" = = "Y"] | | ["$yn" = = "Y"]; Then

echo "OK, continue"

Exit 0

Fi

If ["$yn" = = "N"] | | ["$yn" = = "n"]; Then

echo "Oh, interrupt!"

Exit 0

Fi

echo "I don ' t know your choice is" && exit 0

# A conditional judgment, sub success and failure (else)

If [conditional judgment]; Then

When the conditional judgment is established, the instruction work content can be carried out;

Else

When the conditional judgment is not established, the instruction work content can be carried out;

Fi

# Multiple conditional judgments (if ... else) are performed in a number of different situations (if elif ... elif)

If [conditional judgment type one]; Then

When the conditional judgment is established, the instruction work content can be carried out;

elif [conditional judgment type II]; Then

When the conditional judgment two is established, the instruction work content can be carried out;

Else

When the conditional judgment one and two are not established, the instruction work content can be carried out;

Fi

Multi-Conditional judgment

Read-p "Please input (y/n):" yn

If ["$yn" = = "Y"] | | ["$yn" = = "Y"]; Then

echo "OK, continue"

elif ["$yn" = = "N"] | | ["$yn" = = "n"]; Then

echo "Oh, interrupt!"

Else

echo "I don t know your choice is"

Fi

=====================================

# 1. Let's do some telling.

echo "Now, I'll detect your Linux server ' s services!"

Echo-e "The WWW, ftp, ssh, and mail'll be detect! \ n "

# 2. Start doing some testing, and also output some information!

testing=$ (Netstat-tuln | grep ": 80") # Detect see Port 80 in no?

If ["$testing"! = ""]; Then echo "WWW was running in your system."

Fi

testing=$ (Netstat-tuln | grep ": 22") # detect see Port 22 in no?

If ["$testing"! = ""]; Then

echo "SSH is running in your system."

Fi

testing=$ (Netstat-tuln | grep ": 21") # Detect see Port 21 in no?

If ["$testing"! = ""]; Then

echo "FTP is running in your system."

Fi

testing=$ (Netstat-tuln | grep ": 25") # Detect see port 25 in no?

If ["$testing"! = ""]; Then

echo "Mail is running in your system."

Fi

Use case ... Esac

Case $ variable name in <== keyword for case, there are variables before the rich font size

"First variable content") <== the contents of each variable are suggested to be enclosed in double quotation marks, and the key words are parentheses.

Program Segment

;; <== use two consecutive semicolons to handle each category end!

"Second variable content")

Program Segment

;;

*) <== The last variable content will use * to represent all other values

Other program execution segments that do not contain the contents of the first variable and the contents of the second variable

Exit 1

;;

Esac <== The final case ending! "Turn to write" Think about it!

Case $ in

"Hello")

echo "Hello, how is it?"

;;

"")

echo "You must input parameters, ex> {Someword}"

;;

*) # In fact, the equivalent of a wildcard, 0~ infinite number of arbitrary characters meaning!

echo "Usage $ {Hello}"

;;

Esac

function functions

function fname () {

Program Segment

}

Loop loop

While doing done, the until do-done indeterminate loop

While [condition] <== the state inside the brackets is the judging formula

Do <==do is the beginning of the loop!

Procedure Paragraph

Done <==done is the end of the loop

until [condition]

Do

Procedure Paragraph

Done

For...do...done (fixed cycle)

For Var in con1 con2 Con3 ...

Do

Program Segment

Done

Numerical processing of For...do...done

for (initial value; limit value; execution step))

Do

Program Segment

Done

Shell script Tracking and debug

Linux Learning -10-Learning shell scripts