Shell script preliminary learning-basic learning of laruence Linux Private food

Shell scripts are important for Linux system administrators and O & M personnel. I recently read the shell script. In order to systematically learn the shell script, I read the third edition of "laruence's Linux basic learning for Private food, chapter 1 describes how to learn shell scripts. You can go to the bird's website: Chapter 13th, learning Shell
Scripts takes a look at the examples in this chapter. It is good for beginners to learn shell scripts!

Good habits of writing shell scripts
1. Script functions;
2. script version information;
3. The author and contact information of the script;
4. script version declaration method;
5. Script history (History)
6. Execute special commands in the script in "absolute path" mode;
7. Environment Variable pre-declaration and settings required for script execution.

Sh01.sh

#!/bin/bash# program:# This program show "Hello World!" in your screen# History:# 2013/04/21 15:31 ccf First releasePATH=/bin:/sbin:/usr/bin:/usr/sbin:/usr/local/bin:/usr/local/sbin:~/binexport PATHecho -e "Hello World! \a \n"exit 0

Sh02.sh

#! /Bin/bash # Program # user inputs his first name and last name. program shows his full name. # history #2013/04/21, by CCF, first releasepath =/bin:/sbin:/usr/bin:/usr/sbin:/usr/local/bin: /usr/local/sbin :~ /Binexport pathread-P "Please input your first name:" firstname # prompt the user to enter read-P "Please input your last name: "lastname # Prompt user input echo-e" \ Nyour full name is: $ firstname $ lastname "# The result is output by the screen

Sh03.sh

#! /Bin/bash # Program # program creates three files, which named by user's input # And date command # History: #2013/04/21 Sunday CCF first releasepath =/bin:/sbin: /usr/bin:/usr/sbin:/usr/local/bin:/usr/loacl/sbin :~ /Binexport path #1. ask the user to input the file name and obtain the fileuser variable echo-e "I will use 'touch' command to create 3 files. "# purely display information read-P" Please input your filename: "fileuser # Prompt user input #2. to prevent users from pressing enter at will, use the variable function to analyze whether the file name has been set to filename =$ {fileuser:-"FILENAME"} # Start to determine whether there is a configuration file name #3. start to use the date command to get the required file name date1 =$ (date -- date = '2 Days ago '+ % Y % m % d) # date2 = $ (date -- date = '1 days ago '+ % Y % m % d) # date of the previous day date3 =3 (date + % Y % m % d) # Today's date file1 =1 {filename }$ {date1} # The following three lines are configured in the file name file2 =$ {filename }$ {date2} file3 =3 {filename }$ {date3} #4. create File Name touch "$ file1" Touch "$ file2" Touch "$ file3"

Sh04.sh

#!/bin/bash# Program:# User inputs 2 integer numbers; program will cross these two numbers.# History:# 2013/04/21 ccf19881030  First releasePATH=/bin:/sbin:/usr/bin:/usr/sbin:/usr/local/bin:/usr/local/sbin:~/binexport PATHecho -e "You should input 2 numbers, I will cross them!\n"read -p "first number: "  firstnumread -p "second number: " secondnumtotal=$(($firstnum * $secondnum))echo -e "\nThe result of $firstnum * $secondnum is ==> $total"

Sh05.sh

#! /Bin/bash # program: # user input a filename, program will check the follwing: #1.) exist? 2.) file/directory? 3 .) file permissions # History: #2013/05/14 CCF first releasepath =/bin:/sbin:/usr/bin:/usr/sbin:/usr/local/bin: /usr/local/sbin :~ /Binexport path #1. Ask the user to input the file name and determine whether the user has an input string echo-e "Please input a filename, I will check the filename's type and permission. \ n "# purely display information read-P" input a filename: "FILENAME # Prompt user input test-Z $ filename & Echo" you must input a filename. "& Exit 0 #2. Determine whether the file exists. If not, display the information and end the Script test! -E $ filename & Echo "the filename '$ filename 'do not exist" & Exit 0 #3. Start to judge the file type and attribute test-F $ filename & filetype = "Regular file" test-d $ filename & filetype = "directory" test-r $ filename & perm = "readable" test-W $ filename & perm = "$ perm writeable "test-x $ filename & perm =" $ perm executable "#4. Start to output information! Echo "the filename: $ filename is a $ filetype" Echo "and the permission are: $ perm"

Sh06.sh

#!/bin/bash# Program:#     This program shows the user's choice# History:# 2013/05/14 ccf First releasePATH=/bin:/sbin:/usr/bin:/usr/sbin:/usr/local/bin:/usr/local/sbin:~/binexport PATHread -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 0echo "I don't know what your choice is" && exit 0

You can run shell scripts through SH sh01.sh or chmod A + x sh01.sh;./sh01.sh.