10. The case statement example
#!/bin/bash echo -e "Enter some character : \c" #\c是末尾不加换行符号；＃-e表示激活转义字符。使用-e选项时，将\c特别加以处理，而不会将它当成一般文字输出; read value case $value in [a-z] ) echo "User entered $value a to z" ;; [A-Z] ) echo "User entered $value A to Z" ;; ＃如果运行输入大写字母输出的仍然是上一行的语句，则在终端先执行命令LANG=C [0-9] ) echo "User entered $value 0 to 9" ;; ? ) echo "User entered $value special character" ;; ＃包括任何其他特殊符号比如^&%... * ) echo "Unknown input" ;; esac11. Array variables
#!/bin/bash os=('ubuntu' 'windows' 'kali') os[3]='mac' ＃add new element 'mac' #os[0]='mac' ＃replace 'ubuntu' by 'mac' unset os[2] ＃remove 'kali' echo "${os[@]}" ＃print all echo "${os[1]}" ＃print the second element echo "${!os[@]}" ＃print all index values echo "${#os[@]}" ＃print the total number of elements string=sadfadfadfag echo "${string[@]}" echo "${string[0]}" echo "${string[1]}" echo "${#string[@]}"
12. While loops
#!/bin/bash #while loops n=1 #while [ $n -le 10 ] while (( $n <= 10 )) ＃note the difference of brackets and expression do echo "$n" #n=$((n+1)) #((n++)) (( ++n )) ＃three expressions are all right done
13. Using sleep and open terminal with While loop
#!/bin/bash #while loops n=1 while [ $n -le 10 ] do echo "$n" ((n++)) sleep 1 ＃print $n every one second done #!/bin/bash #while loops n=1 while [ $n -le 3 ] do echo "$n" ((n++)) #gnome-terminal & ＃two methods to open 3 terminals xterm & done14. Read a file content in bash
#!/bin/bash #while loops while read p do echo $p done < hello.sh cat hello.sh | while read p do echo $p done #while IFS= read -r line while IFS=' ' read -r line do echo $line done < /etc/host.conf
15. Until loops
#!/bin/bash # until loops n=1 until [ $n -ge 10 ] #until (( $n -gt 10 )) do echo $n n=$(( n+1 )) done16. For loops
#!/bin/bash # for loops for i in 1 2 3 4 5 do echo $i done for i in {1..10} do echo $i done echo ${BASH_VERSION} for i in {0..10..2} #{start..end..increment} can use above bash version 4.0 do echo $i done for ((i=0; i<5; i++)) do echo $i done17. Use FOR loop to execute command
#!/bin/bash # for loops for command in ls pwd date do echo "----------$command----------" $command ＃execute command done for item in * do if [ -d $item ] #if [ -f $item ] then echo $item fi done
18. Select loop
#!/bin/bash # select loop select name in mark john tom ben do case $name in mark) echo mark selected ;; john) echo john selected ;; tom) echo tom selected ;; ben) echo ben selected ;; *) echo "Error please provide the no. between 1..4" esac done #the same results: select name in mark john tom ben do echo "$name selected" done
19. Break and continue
#!/bin/bash for (( i=1; i<=10; i++ )) do if [ $i -gt 5 ] then break fi echo "$i" done for (( i=1; i<=10; i++ )) do if [ $i -eq 3 -o $i -eq 6 ] then continue fi echo "$i" done以上内容参考bilibili站视频https://www.bilibili.com/video/av51517726
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我终将青春还给了他
连同指尖弹出的盛夏
