Question

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

readonly err_code=256

my_function () {
    return $err_code
}

my_function

echo $? # print 0

如果err_code超过255，则所有最高位将像unsigned byte一样被丢弃，如何解释呢？是否有任何功能文档？我用谷歌搜索了很多没有运气的东西。

谢谢！

更新：

好的，我明白了，它不仅发生在shell中，而且发生在基于Unix的系统中，shell函数也通过命令替换来调用。感谢您提出的问题！

Answer 1

如果您查看admin.py并搜索admin.site.register(CustomUser)，则会发现以下说明：

man bash

如果您真的要返回大于125的值，则可以使用EXIT STATUS代替EXIT STATUS The exit status of an executed command is the value returned by the waitpid system call or equivalent function. Exit statuses fall between 0 and 255, though, as explained below, the shell may use values above 125 specially. Exit statuses from shell builtins and compound commands are also limited to this range. Under certain circumstances, the shell will use special values to indicate specific failure modes. For the shell's purposes, a command which exits with a zero exit status has succeeded. An exit status of zero indicates success. A non-zero exit status indicates failure. When a command terminates on a fatal signal N, bash uses the value of 128+N as the exit status. If a command is not found, the child process created to execute it returns a status of 127. If a command is found but is not executable, the return status is 126. If a command fails because of an error during expansion or redirection, the exit status is greater than zero. Shell builtin commands return a status of 0 (true) if successful, and non-zero (false) if an error occurs while they execute. All builtins return an exit status of 2 to indicate incorrect usage, generally invalid options or missing arguments. Bash itself returns the exit status of the last command executed, unless a syntax error occurs, in which case it exits with a non-zero value. See also the exit builtin command below.，如下所示：

echo

shell函数的返回值不能超过255吗？

1 个答案: