BASH

Question

我能够在单独的脚本上创建 if-elif-then-else 代码块并验证工作正常。但是，当我添加 UNTIL 或 WHILE 逻辑时，我得到了无效响应。如果我手动创建 VALIDATE.txt，我 NOT 期望得到此响应 = "invalid operation" 文件，其中包含 "proceed" 或 "rollback"。请检查下面我的代码

同时脚本

#!/bin/bash
FILE=/Users/lagot/Documents/BASH-TEST/VALIDATE.txt
ACTION=`cat /Users/lagot/Documents/BASH-TEST/VALIDATE.txt >>/dev/null 2>&1`
while [ ! -f "$FILE" ]
do
  echo "not exist"
  sleep 60
done

  if [ "${ACTION}" = "proceed" ];
    then
      echo "performing proceed"
      rm -rf $FILE
  elif [ "${ACTION}" = "rollback" ];
    then
      echo "performing rollback"
      rm -rf $FILE
  else
      echo "invalid operation"
      rm -rf $FILE
  fi

直到脚本

#!/bin/bash
FILE=/Users/lagot/Documents/BASH-TEST/VALIDATE.txt
ACTION=`cat /Users/lagot/Documents/BASH-TEST/VALIDATE.txt >>/dev/null 2>&1`
until [ -f "$FILE" ]
do
   echo "not exist"
   sleep 60
done
if [ "${ACTION}" = "proceed" ];
  then
    echo "performing proceed"
    rm -rf $FILE
elif [ "${ACTION}" = "rollback" ];
  then
    echo "performing rollback"
    rm -rf $FILE
else
    echo "invalid operation"
    rm -rf $FILE
fi

我在单独的 window 上创建了 VALIDATE.txt 并检查了自己

lagot-pc:BASH-TEST lagot$ echo proceed >> VALIDATE.txt
lagot-pc:BASH-TEST lagot$ pwd
/Users/lagot/Documents/BASH-TEST
lagot-pc:BASH-TEST lagot$ cat /Users/lagot/Documents/BASH-TEST/VALIDATE.txt
proceed

我收到无效响应 "invalid operation" 而不是 "performing proceed" 如果我尝试创建 VALIDATE.txt 并在文件

中回显 "rollback"

lagot-pc:BASH-TEST lagot$ ./while-script.sh
not exist
not exist
not exist
not exist
not exist
invalid operation

Answer 1

原始代码的第一部分，更糟糕的是，它在确保 $FILE 存在之前错误地尝试赋值。所以更改这些行：

FILE=/Users/lagot/Documents/BASH-TEST/VALIDATE.txt
ACTION=`cat /Users/lagot/Documents/BASH-TEST/VALIDATE.txt >>/dev/null 2>&1`
until [ -f "$FILE" ]
do
   echo "not exist"
   sleep 60
done

收件人：

FILE=/Users/lagot/Documents/BASH-TEST/VALIDATE.txt
until [ -f "$FILE" ]
do
   echo "not exist"
   sleep 60
done
ACTION=$(<$FILE)

或者，（因为 $(<$FILE) returns 一个错误代码），少一行：

FILE=/Users/lagot/Documents/BASH-TEST/VALIDATE.txt
until { ACTION=$(<$FILE); } 2> /dev/null
do
   echo "not exist"
   sleep 60
done

在那之后，测试 ${ACTION} 的原始代码的其余部分应该可以工作。

不要混淆 >> 重定向（附加到现有文件，如果文件不存在则创建）与 >（覆盖文件，如果文件不存在则创建）。所以这样的代码 echo proceed >> VALIDATE.txt 应该是 echo proceed > VALIDATE.txt，否则如果 VALIDATE.txt 已经存在并且包含 "rollback" 结果将是两行 VALIDATE.txt file:

rollback
proceed

Answer 2

现在已经修复了，我还在下面添加了 UNTIL 和 WHILE 脚本的新格式

在脚本中修复

#!/bin/bash
FILE=/Users/lagot/Documents/BASH-TEST/VALIDATE.txt

while [ ! -f "$FILE" ]
do
  echo "not exist"
  sleep 60
done

  if [ `cat "$FILE"` = "proceed" ];
    then
      echo "performing proceed"
      rm -rf $FILE
  elif [ `cat "$FILE"` = "rollback" ];
    then
      echo "performing rollback"
      rm -rf $FILE
  else
      echo "invalid operation"
      rm -rf $FILE
  fi

在 UNTIL 脚本中修复

#!/bin/bash
FILE=/Users/lagot/Documents/BASH-TEST/VALIDATE.txt

until [ -f "$FILE" ]
do
   echo "not exist"
   sleep 60
done
if [ `cat $FILE` = "proceed" ];
  then
    echo "performing proceed"
    rm -rf $FILE
elif [ `cat $FILE` = "rollback" ];
  then
    echo "performing rollback"
    rm -rf $FILE
else
    echo "invalid operation"
    rm -rf $FILE
fi

BASH - 使用 until 或 while 循环时得到无效响应

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