shell脚本的参数问题

今天药忘吃喽~ 2022-08-06 15:05 184阅读 0赞

一个简单例子  
  
para.sh  
\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#  
\#!/bin/sh  
\#scriptname:para  
  
echo "this script is call $0"  
echo "$0 $1 $2"  
echo "The number  of  positionalparameters is $\#"  
  
echo "$\* is the dollar star"  
  
echo "$@ is the dollar at"  
  
echo " "$\*" is the dollar star which has quoation marks"  
  
echo " "$@" is the dollar at which has quoation marks"  
\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#  
\[root@yqrh5u2\]chmod +x para.sh  
\[root@yqrh5u2 rbf\]\# ./para.sh  1st\_name 2nd\_para 3rd\_last  
this script is call ./para.sh  
./para.sh 1st\_name 2nd\_para  
The number  of  positionalparameters is 3  
1st\_name 2nd\_para 3rd\_last is the dollar star  
1st\_name 2nd\_para 3rd\_last is the dollar at  
1st\_name 2nd\_para 3rd\_last is the dollar star which has quoation marks  
1st\_name 2nd\_para 3rd\_last is the dollar at which has quoation marks  
  
  
  
  
Positional Parameter    What It References  
   
$0          References the name of the script,脚本的名称  
   
$\#          Holds the value of the number of positional parameters，参数的个数  
   
$\*           Lists all of the positional parameters，列出所有的参数  
   
$@          Means the same as $\*, except when enclosed in double quotes  
   
"$\*"        Expands to a single argument (e.g., "$1 $2 $3")，  
   
"$@"       Expands to separate arguments (e.g., "$1" "$2" "$3")  
   
$1 .. $9    References up to nine positional parameters，应用对应的参数  
  
  
 $\* and $@ 区别，只有单他们有双引号是才有区别：  
 $ set 'apple pie' pears peaches  
  
6   $ for i in $@  
    > do  
    > echo $i  
    > done  
  
    apple  
    pie  
    pears  
    peaches  
  
  
  
7   $ set 'apple pie' pears peaches  
8   $ for i in "$@"         \# At last!!  
    > do  
    > echo $i  
    > done  
  
    apple pie  
    pears  
    peaches  
  
  
  
脚本的参数至少是1，  
name=$\{1:?"requires an argument" \}  
  
echo Hello $name  
 :? 将会检验$1是否有值，加入没有，脚本退出，并且报错误信息。