如果希望在shell脚本退出时，执行一些命令（例如，环境清理等），可以使用以下方法：

```bash
trap_exit_fun()
{
  echo "exit code: $?"
  # do something...
}

trap trap_exit_fun EXIT

……
```

实例（demo.sh）：

```bash
set -eo pipefail

trap_exit_fun()
{
  exit_code=$?
  echo "exit code: $exit_code"
  if [ "$exit_code" != "0" ]; then
    echo "error!"
  fi
}

trap trap_exit_fun EXIT

echo "start"
xxxxx  # error here
echo "end"
```

执行结果：

```bash
[yz@bogon demo]$ sh demo.sh
start
demo.sh: line 15: xxxxx: command not found
exit code: 127
error!
[yz@bogon demo]$ echo $?
127
```