Question

我是Bash脚本的新手，尽管多次尝试重构伪代码中显示的逻辑结构，但我无法使其工作。如何将if / else逻辑与for循环一起分割？

伪代码：我有一个命令检查HDFS文件系统的目录中是否存在任何子文件夹。让我们调用这个命令_A。

If subfolders do NOT exist {
    proceed with remaining execution of script
}
Else {
    sleep for 30 minutes and run command_A again to see if the subfolders have been removed.  Note:  This sleep and re-check cycle should repeat up to 4 times and if subfolders are never removed the script is killed with exit 1
}

我试过的样本如下。我无法弄清楚我应该如何使用||与else语句一起使用。

使用这些结构：

1. for i in {1..4}; do command_A && break || sleep 1800; done
2. if command_A ; then echo "Command succeeded" else echo "Command failed" fi

测试示例：

for i in {1..4};
  do
     if hdfs dfs -test -e $mypath/*
       echo "Folder is empty" && break
else
     ???

更新显示工作解决方案 ：

for i in {1..4};
  do
   if hdfs dfs -test -e $mypath/*;
     then
       if [ $i -eq 4 ]
        then
          echo "script exiting now with code 1"
       else
          echo "Folder is full"
          sleep 10
       fi
   else
    echo "Folder is empty"
    break
  fi
done

Answer 1

<强>更新

这是针对此特定问题的完整代码，我将保留原始稍微更通用的代码以供将来参考，因为对于搜索类似问题的其他人来说，它不那么复杂（如果/ else则嵌套少）。

for i in {1..4};
  do
   if hdfs dfs -test -e $mypath/*;
     then
       if [ $i -eq 4 ]
        then
          echo "script exiting now with code 1"
       else
          echo "Folder is full"
          sleep 10
       fi
   else
    echo "Folder is empty"
    break
  fi
done

我认为这样的事情会起作用，这就是你所拥有的。您只需将您要检查的内容放在if语句中，此代码应该适合您。

for i in {1..4}
do
   if [ <check for subdirs> ]
   then 
       echo "Folder is empty!" 
       break
   else
       sleep 1800
   fi
done

Answer 2

这会有用吗？

sleep_count=0
max_attempts=4
for ((i=0; i < $max_attempts; i++)); do
  if hdfs dfs -test -e $mypath/*; then
     echo "No subfolders!"
     break
  else
     # subfolders exist; wait for a while and see if they go away
     ((sleep_count++))
     sleep 1800
  fi
done

if [[ $sleep_count == $max_attempts ]]; then
  # waited too long for subfolders to go away
  exit 1
fi

# probably repeat the above steps again?

Bash脚本 - for循环和if-else

2 个答案: