的if else语句

Question

我要问这个问题：“你想用什么格式？”，那么，这取决于答案是否xml或json，打印适当的输出。但是，如果它不是xml或json，则代码结束。

代码：

#!/bin/bash 
read -r -e -p "What format do you want to use? json/xml?: " format 

if [[ "${format,,}" == "json" ]]; then 
    curl=$curl"\"\Content-Type: application/json\"\ 
else [[ "${format,,}" == "xml" ]]; then 
    curl=$curl"\"\Content-Type: application/xml\"\ 
elif [[ "${format,,}" == "no" ]]; then 
    echo "Goodbye, you must specify a format to use Rest" 
else 
    echo "Unknown" 
    exit 0 
fi 
echo $curl 

我收到此错误，当我尝试运行它：

[root@osprey groups]# ./test3 
What format do you want to use? json/xml?: xml 
./test3: line 8: syntax error near unexpected token `then' 
./test3: line 8: `elif [[ "${format,,}" == "no" ]]; then' 

Answer 1

我会用时间长一点，但更人性化的变种：

err() { echo "$@" >&2; return 1; } 

show_help() { 
cat - >&2 <<EOF 
You must specify a format to use Rest because bla bla... 
EOF 
} 

select_format() { 
    PS3="Select the format do you want to use?> " 
    select ans in json xml "quit program"; do 
     case "$REPLY" in 
      [0-9]*) answer=$ans;; 
      *) answer=$REPLY;; 
     esac 
     case "${answer,,}" in 
      '') ;; 
      j|js|json) echo '-H "Content-Type: application/json"' ; return 0 ;; 
      x|xml)  echo '-H "Content-Type: application/xml"' ; return 0 ;; 
      q|quit*) err "Bye..." ; return 1;; 
      h|help) show_help ;; 
      *) err "Unknown format $answer" ;; 
     esac 
    done 
    [[ "$answer" ]] || return 1 #handles EOF (ctrl-D) 
} 

curl_args=() 
curl_args+=($(select_format)) || exit 1 
echo curl "${curl_args[@]}" 

它显示一个菜单：

1) json 
2) xml 
3) quit program 
Select the format do you want to use?> 

，并且用户可以输入：

• 任一相应的数字
• 或j，js，json对JSON和x，xml的XML
• h的帮助
• 和q的退出...
• 不正确的（错误输入）的答案被处理，并再次要求.. 。

Answer 2

正确的语法是

if ... 
elif ... 
else ... 
fi 

else必须遵循的命令，而不是一个条件和; then。

Answer 3

#!/bin/bash 
read -r -e -p "What format do you want to use? json/xml?: " format 

if [[ "${format,,}" == "json" ]]; then 
    curl=$curl"\"Content-Type: application/json\"" 
elif [[ "${format,,}" == "xml" ]]; then 
    curl=$curl"\"Content-Type: application/xml\"" 
elif [[ "${format,,}" == "no" ]]; then 
    echo "Goodbye, you must specify a format to use Rest" 
else 
    echo "Unknown" 
    exit 0 
fi 
echo $curl 

应该工作。如果没有，则问题不在于if/else语句。

编辑：发现问题。这是不正确的使用引号。我试图解决它，所以上面应该现在工作。

Answer 4

选项和参数应存储在数组中，而不是一个单一的字符串。此外，这里的陈述会更简单。

#!/bin/bash 

curl_opts=() 
read -r -e -p "What format do you want to use? json/xml?: " format 

shopt -s nocasematch 
case $format in 
    json) curl_opts+=(-H "Content-Type: application/json") ;; 
    xml) curl_opts+=(-H "Content-Type: application/xml") ;; 
    no) printf 'Goodbye, you must specify a format to use Rest\n' >&2 
     exit 1 
     ;; 
    *) printf 'Unknown format %s, exiting\n' "$format" >&2 
     exit 1 
     ;; 
esac 

curl "${curl_opts[@]}" ...