bash on ubuntu 16：set -e不继承subshel​​l

Question

当我运行此命令时

set -e; echo $(echo "$-");

我得到himBH作为输出。我期待字母e包含在输出中。怎么回事？

我正在使用Ubuntu 16.04.1 LTS GNU bash，版本4.3.46（1）-release（x86_64-pc-linux-gnu）

Answer 1

除非您处于POSIX模式或使用errexit shell选项（添加到inherit_errexit 4.4），否则命令替换不会继承bash选项。

192% bash -ec 'echo "$(echo "$-")"'
hBc
192% bash --posix -ec 'echo "$(echo "$-")"'
ehBc
192% bash -O inherit_errexit -ec 'echo "$(echo "$-")"'  # 4.4+
ehBc

Answer 2

这个问题！ 研究了几个小时，直到我找到了 htis。

我无法将 set -e 继承到子 shell。

这是我的概念证明：

#!/usr/bin/env bash
set -euo pipefail

# uncomment to handle failures properly
# shopt -s inherit_errexit

function callfail() {
  echo "SHELLOPTS - callfail - $SHELLOPTS" >&2
  local value
  value=$(fail)
  echo "echo will reset the result to 0"
}

function fail() {
  echo "SHELLOPTS - fail     - $SHELLOPTS" >&2
  echo "failing" >&2
  return 1
}

function root() {
  local hello
  hello=$(callfail)
  echo "nothing went bad in callfail"
  callfail
  echo "nothing went bad in callfail"
}

root

没有 shopt -s inherit_errexit 的执行：

$ ./test.sh         
SHELLOPTS - callfail - braceexpand:hashall:interactive-comments:nounset:pipefail
SHELLOPTS - fail     - braceexpand:hashall:interactive-comments:nounset:pipefail
failing
nothing went bad in callfail
SHELLOPTS - callfail - braceexpand:errexit:hashall:interactive-comments:nounset:pipefail
SHELLOPTS - fail     - braceexpand:hashall:interactive-comments:nounset:pipefail
failing

使用 shopt -s inherit_errexit 执行：

$ ./test.sh
SHELLOPTS - callfail - braceexpand:errexit:hashall:interactive-comments:nounset:pipefail
SHELLOPTS - fail     - braceexpand:errexit:hashall:interactive-comments:nounset:pipefail
failing