【Linux学习】——Shell编程基础

Shell编程基础

创建Shell脚本

#!/bin/bash
#showHllo.sh
#To shew hello to somebody
echo -n "Enter Your Name:"
read NAME
echo "Hello,$NAME!"

执行脚本

$ /bin/bash ShowHello.sh
$ bash ShowHello.sh

$ chmod a+x ShowHello.sh
$ ./ShowHello.sh

变量

输出命令echo

#!/bin/bash
echo   This is a test
echo   "This is a test"
echo    'This is a test'


root@pailanglee-virtual-machine:/home/pailanglee# cat 10_3.sh
#!/bin/bash
echo   This is a test
echo   "This is a test"
echo    'This is a test'
root@pailanglee-virtual-machine:/home/pailanglee# bash 10_3.sh
This is a test
This is a test
This is a test

变量规则

#!/bin/bash
sal=Hello
echo $sal
sal="Yes Dear"
echo $sal
read sal
echo " This is $sal"
sal="Hello"
sal=$sal",how are you."
echo $sal
sal=$pwd
echo $sal
sal=$(pwd)
echo $sal



root@pailanglee-virtual-machine:/home/pailanglee# bash bianliang.sh 
Hello
Yes Dear
make
 This is make
Hello,how are you.

/home/pailanglee
root@pailanglee-virtual-machine:/home/pailanglee# 

#!/bin/bash
ls *.txt>.rm_log
rm  *.txt  

root@pailanglee-virtual-machine:/home/pailanglee# touch f1.txt
root@pailanglee-virtual-machine:/home/pailanglee# bash txtrm.sh 
root@pailanglee-virtual-machine:/home/pailanglee# ls 
10_3.sh     视频  音乐          cos_value.c  hello.c    main.c       test.c
3186004050  图片  桌面          f1.sh        hello.o    makefile     ts1.lnk
公共的      文档  a.out         haha.c       hello.pre  sin_value.c  ts2.lnk
模板        下载  bianliang.sh  hello        hello.s    snap         txtrm.sh
root@pailanglee-virtual-machine:/home/pailanglee# ls -a
.           下载           .config      hello.s      .ssh
..          音乐           cos_value.c  .local       .sudo_as_admin_successful
10_3.sh     桌面           f1.sh        main.c       test.c
3186004050  a.out          .gnupg       makefile     .thunderbird
公共的      .bash_history  haha.c       .mozilla     ts1.lnk
模板        .bash_logout   hello        .profile     ts2.lnk
视频        .bashrc        hello.c      .rm_log      txtrm.sh
图片        bianliang.sh   hello.o      sin_value.c
文档        .cache         hello.pre    snap

#!/bin/bash
today=$(date +%y%m%d)
#date +%y等按照指定的格式显示
ls /usr/bin -al>log.$today



root@pailanglee-virtual-machine:/home/pailanglee# touch data.sh
root@pailanglee-virtual-machine:/home/pailanglee# cat data.sh 
root@pailanglee-virtual-machine:/home/pailanglee# cat > data.sh 
#!/bin/bash
today=$(date +%y%m%d)
#date +%y等按照指定的格式显示
ls /usr/bin -al>log.$today

root@pailanglee-virtual-machine:/home/pailanglee# 
root@pailanglee-virtual-machine:/home/pailanglee# bash data.sh 
root@pailanglee-virtual-machine:/home/pailanglee# ls
10_3.sh     图片  a.out         haha.c     hello.s      snap
3186004050  文档  bianliang.sh  hello      log.201122   test.c
公共的      下载  cos_value.c   hello.c    main.c       ts1.lnk
模板        音乐  data.sh       hello.o    makefile     ts2.lnk
视频        桌面  f1.sh         hello.pre  sin_value.c  txtrm.sh
root@pailanglee-virtual-machine:/home/pailanglee# 

#!/bin/bash
read a
b=$a$(pwd)
echo $b



root@pailanglee-virtual-machine:/home/pailanglee# touch reada.sh
root@pailanglee-virtual-machine:/home/pailanglee# cat > reada.sh 
#!/bin/bash
read a
b=$a$(pwd)
echo $b
root@pailanglee-virtual-machine:/home/pailanglee# 
root@pailanglee-virtual-machine:/home/pailanglee# bash reada.sh 
long long 
long long/home/pailanglee

unset命令

#!/bin/sh
foo="Hello World"
echo $foo
unset foo
echo $foo


root@pailanglee-virtual-machine:/home/pailanglee# cat > foo.sh
#!/bin/sh
foo="Hello World"
echo $foo
unset foo
echo $foo
root@pailanglee-virtual-machine:/home/pailanglee# 
root@pailanglee-virtual-machine:/home/pailanglee# bash foo.sh
Hello World

引号的规则

#!/bin/sh
myvar="Hi there"
echo $myvar
echo "$myvar"
echo '$myvar'
echo $myvar
echo Enter some text
read myvar
echo '$myvar' now equals $myvar
exit 0

root@pailanglee-virtual-machine:/home/pailanglee# cat > variable.sh
#!/bin/sh
myvar="Hi there"
echo $myvar
echo "$myvar"
echo '$myvar'
echo $myvar
echo Enter some text
read myvar
echo '$myvar' now equals $myvar
exit 0
root@pailanglee-virtual-machine:/home/pailanglee# bash variable.sh
Hi there
Hi there
$myvar
$myvar
Enter some text
hi
$myvar now equals hi

环境变量

root@pailanglee-virtual-machine:/home/pailanglee# cat huanjing.sh
cat: huanjing.sh: 没有那个文件或目录
root@pailanglee-virtual-machine:/home/pailanglee# cat >  huanjing.sh
#!/bin/sh
echo $HMOE    
echo This is Home
echo $PATh
root@pailanglee-virtual-machine:/home/pailanglee# vi huanjing.sh 
root@pailanglee-virtual-machine:/home/pailanglee# cat huanjing.sh 
#!/bin/sh
echo $HMOE
echo This is Home
echo $PATH

root@pailanglee-virtual-machine:/home/pailanglee# cat>> huanjing.sh 
echo $SHELL
root@pailanglee-virtual-machine:/home/pailanglee# cat huanjing.sh 
#!/bin/sh
echo $HMOE
echo This is Home
echo $PATH

echo $SHELL
root@pailanglee-virtual-machine:/home/pailanglee# bash huanjing.sh 

This is Home
/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/usr/games:/usr/local/games
/bin/bash

系统变量

#!/bin/sh
salutation="Hello"
echo $salutation
echo "The program $0 is now running"
echo "The second parameter was $2"
echo "The first parameter was $1"
echo "The parameter list was $*"
echo "The user's home directory is $HOME"
echo "Please enter a new greeting"
read salutation
echo $salutation
echo "The script is now complete"
exit 0



root@pailanglee-virtual-machine:/home/pailanglee# cat > ry_var.sh
#!/bin/sh
salutation="Hello"
echo $salutation
echo "The program $0 is now running"
echo "The second parameter was $2"
echo "The first parameter was $1"
echo "The parameter list was $*"
echo "The user's home directory is $HOME"
echo "Please enter a new greeting"
read salutation
echo $salutation
echo "The script is now complete"
exit 0


root@pailanglee-virtual-machine:/home/pailanglee# bash ry_var.sh 
Hello
The program ry_var.sh is now running
The second parameter was 
The first parameter was 
The parameter list was 
The user's home directory is /root
Please enter a new greeting
HI
HI
The script is now complete


root@pailanglee-virtual-machine:/home/pailanglee# bash ry_var.sh a b c d
Hello
The program ry_var.sh is now running
The second parameter was b
The first parameter was a
The parameter list was a b c d
The user's home directory is /root
Please enter a new greeting
mk
mk
The script is now complete