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Shell简介 Shell简单的说就是命令解析器，将用户输入的指令转换为相应的机器能够执行的程序。 Shell脚本是一个包含一系列命令序列的文本文件（批处理）。当运行这个脚本文件时，文件中包含的命令序列将得到执行。 HelloWorld Shell脚本的第一行必须是如下格式： #!/bin/bash 符号#!用来指定该脚本文件的解析程序。例中使用bash，也可以使用其他shell。如#!/bin/sh。 当编辑好脚本后，必须使其具有可执行属性。 chmod +x filename Shell脚本hello.sh view plaincopy to clipboardprint? #!/bin/bash echo "hello world!" mkdir ./helloworld #!/bin/bash echo "hello world!" mkdir ./helloworld Shell中的变量 在Shell编程中，所有的变量都由字符串组成，并不需要预先对变量声明。 Shell脚本s1.sh view plaincopy to clipboardprint? #!/bin/sh #号后面是注释 #set variable a a="hello" #print a echo "A is: $a" #!/bin/sh #号后面是注释 #set variable a a="hello" #print a echo "A is: $a" 命令行参数传递 $#:传入脚本的命令行参数个数 $*:所有的命令行参数，各参数值之间留有空格 $0:命令本身（shell文件名） $1:第一个命令行参数 $2:第二个命令行参数 shell脚本s2.sh view plaincopy to clipboardprint? #!/bin/sh echo "numer of vars:"$# echo "values of vars:"$* echo "value of var1:"$1 echo "value of var2:"$2 echo "value of var3:"$3 echo "value of var4:"$4 #!/bin/sh echo "numer of vars:"$# echo "values of vars:"$* echo "value of var1:"$1 echo "value of var2:"$2 echo "value of var3:"$3 echo "value of var4:"$4 运行 ./s2.sh a b c d 输出结果： numer of vars:4 values of vars:a b c d value of var1:a value of var2:b value of var3:c value of var4:d Shell中的局部变量 shell脚本s3.sh view plaincopy to clipboardprint? #!/bin/bash hello="var1" echo $hello function funcl { local hello="var2" echo $hello } funcl echo $hello #!/bin/bash hello="var1" echo $hello function funcl { local hello="var2" echo $hello } funcl echo $hello 在变量首次被赋值时加上local关键字可以声明一个局部变量 注意：(1)变量赋值时，“=”左右两边都不能有空格 (2)BASH中的语句结尾不需要分号 Shell中的控制结构 if语句 if[expression] then #code block if if[expression] then #code block else #code block fi 比较运算符 比较操作 整数操作 字符串操作 比较操作 整数操作 字符串操作 相同 -eq = 大于或等于 -ge 不同 -ne != 小于或等于 -le 大于 -gt > 为空 -z 小于 -lt < 不为空 -n 使用实例： 比较整数a是否大于整数b： if[ $a -gt $b ] 判断字符串a是否为空： if[ -z $a ] 注意： (1)在"["和"]"符号的左右都留有空格 (2)"="左右都有空格 shell脚本s4.sh view plaincopy to clipboardprint? #!/bin/bash a=$1 b=$2 if [ -z $a ] || [ -z $b ] then echo "please enter 2 no" exit 1 fi if [ $a -eq $b ] ; then echo "number a = number b" else if [ $a -gt $b ] then echo "number a>number b" elif [ $a -lt $b ] then echo "number a<number b" fi fi #!/bin/bash a=$1 b=$2 if [ -z $a ] || [ -z $b ] then echo "please enter 2 no" exit 1 fi if [ $a -eq $b ] ; then echo "number a = number b" else if [ $a -gt $b ] then echo "number a>number b" elif [ $a -lt $b ] then echo "number a<number b" fi fi 判断 -e 文件已经存在 -f 文件是普通文件 -s 文件大小不为零 -d 文件是一个目录 -r 文件对当前用户可以读取 -w 文件对当前用户可以写入 -x 文件对当前用户可以执行 shell脚本s5.sh view plaincopy to clipboardprint? #!/bin/sh folder=/home [ -r "$folder" ] && echo "Can read $folder" [ -f "$folder" ] || echo "this is not file" #!/bin/sh folder=/home [ -r "$folder" ] && echo "Can read $folder" [ -f "$folder" ] || echo "this is not file" shell脚本s6.sh view plaincopy to clipboardprint? #!/bin/bash DIR=$1 #if the string empty if [ "$DIR" = " " ] then echo "usage: `basename $0` directory to create" >&2 exit 1 fi echo "dir" $DIR if [ -d $DIR ] then echo "The directory already exist" exit 0 else echo "The directory does exist" echo -n "Create is now? [Y/N]:" read create if [ "$create" = "y" ] || [ "$create" = "Y" ] then echo "creating now" if [ mkdir $DIR ] DIR=" " fi if [ "$DIR" = " " ] then echo "create directory sucess" else echo "create directory error" fi elif [ "$create" = "n" ] || [ "$create" = "N" ] then echo "does not create directory" exit 0 else echo "Errors order" exit 1 fi fi #!/bin/bash DIR=$1 #if the string empty if [ "$DIR" = " " ] then echo "usage: `basename $0` directory to create" >&2 exit 1 fi echo "dir" $DIR if [ -d $DIR ] then echo "The directory already exist" exit 0 else echo "The directory does exist" echo -n "Create is now? [Y/N]:" read create if [ "$create" = "y" ] || [ "$create" = "Y" ] then echo "creating now" if [ mkdir $DIR ] DIR=" " fi if [ "$DIR" = " " ] then echo "create directory sucess" else echo "create directory error" fi elif [ "$create" = "n" ] || [ "$create" = "N" ] then echo "does not create directory" exit 0 else echo "Errors order" exit 1 fi fi for循环 for循环结构与C语言中有所不同，在bash中for循环的基本结构式 for var in [list] do #code lock done 其中$var是循环控制变量，[list]是var遍历的一个集合，do/done对包含了循环体。 另外，如果for和do写在同一行，必须在do前面加";"。 shell脚本s7.sh view plaincopy to clipboardprint? #!/bin/bash for day in Sun Mon Tue Wed Thu Fri Sat do echo $day done #!/bin/bash for day in Sun Mon Tue Wed Thu Fri Sat do echo $day done shell脚本统计当前目录下的文件数 view plaincopy to clipboardprint? #!/bin/bash counter=0 for files in * do counter=`expr $counter + 1` done echo "There are $counter files in `pwd` we need to process" #!/bin/bash counter=0 for files in * do counter=`expr $counter + 1` done echo "There are $counter files in `pwd` we need to process" shell脚本将用户输入的数字按倒序的方式输出 view plaincopy to clipboardprint? #!/bin/bash echo -n "Pleasw enter number : " read n sd=0 rev="" on=$n echo "$n" while [ $n -gt 0 ] do sd=$(( $n % 10 )) # get Remainder n=$(( $n / 10 )) # get next digit rev=$( echo $rev$sd) done echo "$on in a reverse order $rev" #!/bin/bash echo -n "Pleasw enter number : " read n sd=0 rev="" on=$n echo "$n" while [ $n -gt 0 ] do sd=$(( $n % 10 )) # get Remainder n=$(( $n / 10 )) # get next digit rev=$( echo $rev$sd) done echo "$on in a reverse order $rev" until循环 until循环的基本结构 until [condition] do #code block done while和until的区别在于while是为真时执行，until是为假时执行。 shell脚本 移动一个文件，如果目标存在，监视该文件，直到文件被删除才移动文件。 view plaincopy to clipboardprint? #!/bin/bash if [ "$1" = "" ] || [ "$2" = "" ] then echo "Please enter file name" exit 1 fi if [ -e $2 ] then echo "The file already exists" until [ ! -f $2 ] do sleep 1 done fi if [ ! `mv $1 $2` ] then echo "mv sucessful" else echo "mv error" fi #!/bin/bash if [ "$1" = "" ] || [ "$2" = "" ] then echo "Please enter file name" exit 1 fi if [ -e $2 ] then echo "The file already exists" until [ ! -f $2 ] do sleep 1 done fi if [ ! `mv $1 $2` ] then echo "mv sucessful" else echo "mv error" fi case语句 case语句结构 case "$var" in condition1) ;; condion2) ;; *) default statments;; esac shell脚本 判断键盘输入大小写 view plaincopy to clipboardprint? #!/bin/bash echo "Hit a key, then hit return." read Keypress case "$Keypress" in [A-Z] ) echo "Uppercase letter";; [a-z] ) echo "Lowercase letter";; [0-9] ) echo "Digit";; * ) echo "Punctuation, whitespace, or other";; esac #!/bin/bash echo "Hit a key, then hit return." read Keypress case "$Keypress" in [A-Z] ) echo "Uppercase letter";; [a-z] ) echo "Lowercase letter";; [0-9] ) echo "Digit";; * ) echo "Punctuation, whitespace, or other";; esac (责任编辑：IT) |