在shell中编写try-catch-finally

Question

是否有像java try catch finally这样的linux bash命令？还是linux shell总是在运行？

try {
   `executeCommandWhichCanFail`
   mv output
} catch {
    mv log
} finally {
    rm tmp
}

Answer 1

我在脚本中成功地使用了以下语法：

# Try, catch, finally
(echo "try this") && (echo "and this") || echo "this is the catch statement!"

# this is the 'finally' statement
echo "finally this"

如果try语句抛出错误或以exit 1结束，那么解释器将继续执行catch语句，然后执行finally语句。

如果两个try语句都成功（和/或以退出结束），解释器将跳过catch语句，然后运行finally语句。

示例1：

goodFunction1(){
  # this function works great
  echo "success1"
}

goodFunction2(){
  # this function works great
  echo "success2"
  exit
}

(goodFunction1) && (goodFunction2) || echo "Oops, that didn't work!"

echo "Now this happens!"

输出\u 1

success1
success2
Now this happens!

示例\u 2

functionThrowsErr(){
  # this function returns an error
  ech "halp meh"
}

goodFunction2(){
  # this function works great
  echo "success2"
  exit
}

(functionThrowsErr) && (goodFunction2) || echo "Oops, that didn't work!"

echo "Now this happens!"

输出\u 2

main.sh: line 3: ech: command not found
Oops, that didn't work!
Now this happens!

Example_3

functionThrowsErr(){
  # this function returns an error
  echo "halp meh"
  exit 1
}

goodFunction2(){
  # this function works great
  echo "success2"
}

(functionThrowsErr) && (goodFunction2) || echo "Oops, that didn't work!"

echo "Now this happens!"

Output_3

halp meh
Oops, that didn't work!
Now this happens!

请注意，函数的顺序将影响输出。如果您需要两个语句分别尝试和捕获，请使用两个try catch语句。

(functionThrowsErr) || echo "Oops, functionThrowsErr didn't work!"
(goodFunction2) || echo "Oops, good function is bad"

echo "Now this happens!"

输出

halp meh
Oops, functionThrowsErr didn't work!
success2
Now this happens!

Answer 2

嗯，有点：

{ # your 'try' block
    executeCommandWhichCanFail &&
    mv output
} || { # your 'catch' block
    mv log
}

 rm tmp # finally: this will always happen

Answer 3

根据您的示例，看起来您正在尝试执行类似于总是删除临时文件的操作，而不管脚本如何退出。在Bash中，尝试使用内置命令捕获退出信号。

#!/bin/bash

trap 'rm tmp' EXIT

if executeCommandWhichCanFail; then
    mv output
else
    mv log
    exit 1 #Exit with failure
fi

exit 0 #Exit with success

脚本退出时，始终执行陷阱中的rm tmp语句，因此将始终尝试删除文件“tmp”。

安装的陷阱也可以重置；仅使用信号名称调用陷阱将重置信号处理程序。

trap EXIT

有关更多详细信息，请参阅bash手册页面：ManBash