127从$返回代码？

Question

返回值127的含义是什么？在UNIX中.

Answer 1

/bin/sh当在PATH系统变量中找不到给定命令且它不是内置shell命令时,返回值127 .换句话说,系统不理解您的命令,因为它不知道在哪里找到您要调用的二进制文件.

Answer 2

通常它意味着:

127 - 找不到命令

但它也可能意味着命令被发现,
但被命令时所需的库中没有找到.

Answer 3

127 - command not found

示例:$ caat错误消息将

庆典:

caat:命令未找到

现在你检查使用 echo $?

Answer 4

一个shell约定是一个成功的可执行文件应该以值0退出.任何其他东西都可以被解释为某种类型的失败,部分是bash或刚刚运行的可执行文件.另请参阅bash手册页的$ PIPESTATUS和EXIT STATUS部分:

   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 com-
   mand 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.

   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.

Answer 5

它没有特殊意义,除了退出的最后一个进程,退出状态为127.

但是,它也被bash使用(假设您使用bash作为shell)告诉您无法执行您尝试执行的命令(即无法找到它).遗憾的是,如果进程以状态127退出,或者如果找不到,则不能立即进行推理.

编辑:
除了控制台上的输出外,不能立即推导,但这是堆栈溢出,所以我假设你在脚本中这样做.