linux - 出现错误时从 bash 函数可靠退出

Question

所以我了解到 set -e 在 Bash 函数中没有任何作用，需要将 set -o errexit 与 trap 结合起来如果发生错误，自动从函数内退出。不幸的是，如果在 if 语句内调用函数或与 && 或 || 组合使用，这似乎不起作用。

假设我设置了这样的错误处理:

#!/bin/bash
set -e
set -o errtrace
trap 'rc=$?; echo "ERROR catched."; exit $rc' ERR

function myfunc() {
  bad_command
  echo "SUCCESS!"
}

我得到了以下期望的结果:

myfunc
test.sh: line 7: bad_command: command not found
ERROR catched.

myfunc | cat
test.sh: line 7: bad_command: command not found
ERROR catched.

a=$(myfunc)
test.sh: line 7: bad_command: command not found
ERROR catched.

以及这些不受欢迎的结果:

myfunc || true
test.sh: line 7: bad_command: command not found
SUCCESS!

myfunc && true
test.sh: line 7: bad_command: command not found
SUCCESS!

if myfunc; then true; fi
test.sh: line 7: bad_command: command not found
SUCCESS!

无论函数如何执行，如何确保函数内的执行始终被中止？

Answer 1

参见trap documentation ，具体来说 -

If a sigspec is ERR, the command arg is executed whenever a simple command has a non-zero exit status, subject to the following conditions. The ERR trap is not executed if the failed command is part of the command list immediately following a while or until keyword, part of the test in an if statement, part of a && or || list, or if the command's return value is being inverted via !.

您使用 errtrace 的方法是正确的，但是当命令已经进行了条件测试时，ERR 陷阱将被忽略。

来自GNU Bash Manual功能页面 -

All other aspects of the shell execution environment are identical between a function and its caller with these exceptions: the DEBUG and RETURN traps are not inherited unless the function has been given the trace attribute using the declare builtin or the -o functrace option has been enabled with the set builtin, (in which case all functions inherit the DEBUG and RETURN traps), and the ERR trap is not inherited unless the -o errtrace shell option has been enabled. See Bourne Shell Builtins, for the description of the trap builtin.

因此，您可以使用 functrace 绕过此问题，并根据需要手动检查 DEBUG 选项。

set -o functrace
trap 'rc=$?; if ((rc)) then echo "ERROR $rc caught."; exit $rc; fi' debug

跳过set -e，但了解exit是中止脚本，而不仅仅是从函数返回。