http://www.ruanyifeng.com/blog/2017/11/bash-set.html

#!/usr/bin/env bash
set -u

echo $a
echo bar

$ bash script.sh
bash: script.sh:行4: a: 未绑定的变量

#!/usr/bin/env bash
set -x

echo bar

$ bash script.sh
+ echo bar
bar

#!/usr/bin/env bash

foo
echo bar

$ bash script.sh
script.sh:行3: foo: 未找到命令
bar

#!/usr/bin/env bash
set -e

foo
echo bar

$ bash script.sh
script.sh:行4: foo: 未找到命令

#!/usr/bin/env bash
set -e

foo | echo a
echo bar

$ bash script.sh
a
script.sh:行4: foo: 未找到命令
bar

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

foo | echo a
echo bar

$ bash script.sh
a
script.sh:行4: foo: 未找到命令