重击：正确处理错误 [英] Bash: proper handling of errors

问题描述

我的bash脚本类似于：

I have bash script similar to:

{
  # Try block
  command 1
  command 2
  command 3
} || {
  # Catch errors
  while true; do
  {
    # Try block inside
    # Change parameters for command 1, command 2
    command 1
    command 2
    command 3
    break
  } || {
      # Change parameters and try again
      continue
  }
done
}

此代码或多或少可以正常工作，但是...

More or less this code works fine, but...

出于某些原因尝试部分的工作对我而言不是预期的。我以为如果我的某些命令未返回 0 代码会失败，但这不是真的。

For some reason try sections works not as expected for me. I thought that it fails if some of my commands return not 0 code, but it's not true.

对于某些命令特定情况下，我的命令2 在第一个try块中返回 1 代码，但它不会失败，并进入 catch 部分， command 3 从此 try 块执行，即

For some specific cases my command 2 returns 1 code in the first try block, but it doesn't fail and goes into catch section, command 3 executes from this try block and that's it.

这是我的问题：

如何处理bash中的错误？只是为了玩返回码？

How to handle errors in bash? Just to play with return codes?

更新：

原始代码看起来非常类似于：
主要思想是所有3个命令应一个接一个地执行，并且它们都以某种方式与 folder_name 相关。

Original code looks very similar to: The main idea is that all 3 commands should be executed one-by-one and all of them are somehow related to folder_name.

folder_name=my_folder
suffix=0
{
  cd /home/test/
  mkdir $folder_name
  ls -la $folder_name
} || {
    while true; do
      suffix=$(expr $suffix + 1)
      {
        folder_name=$folder_name_$suffix
        cd /home/test/
        mkdir $folder_name
        ls -la $folder_name
        break
      } || {
          continue
      }
    done
}

推荐答案

我在这里看到两个问题。

I see two problems here.

使用花括号对命令进行分组时，必须<分>必须在末尾（或右大括号前的换行符）。请参考此处的文档

When grouping commands using curly braces, there must be a semicolon at the end (or a newline before the closing brace). Refer to docs here

另一方面，无论如何您都不考虑返回码。通常，您使用 [[$？ -eq 0]] 。但是在这里，您可以简单地用&& 链接命令。
例如

On the other hand, you are not considering return codes anyway. You normally check the return code with something like [[ $? -eq 0 ]]. But in here, you can simply chain the commands with &&. e.g.

{
  cd /home/test/ && 
  mkdir $folder_name &&
  ls -la $folder_name;
}

但是，以下操作将满足您的需求。

However, following will do what you need.

cd /home/test/
prefix=my_folder                                                                                                                                      
suffix=0

folder_name="$prefix"
while true; do
  if [[ -e $folder_name ]]; then
    folder_name="${prefix}_$((++suffix))"
    continue
  fi  
  mkdir "$folder_name"
  if [[ $? -ne 0 ]]; then
    echo "mkdir failed"
    exit 1
  fi  
  break
done

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