Linux如何通过错误号获取错误描述 [英] Linux How to get error description by error number

问题描述

在linux系统中(特别是我有Ubuntu 14)，如果某些程序因错误而终止，我可以通过$?变量获取数字错误代码

In linux (specifically I have Ubuntu 14) if some program terminates with an error, I can get numerical error code via $? variable

$ ./failing_app
$ echo $?

但是数字本身并不能告诉我太多，如何获得错误名称和描述?

However the number itself does not tell me much, how do I get error name and description?

$ man errno中有一个错误列表，但仅提供名称，而不提供数值.

There is a list of errors in $ man errno but it gives only names, not numerical values.

我已经搜索过google，结果非常奇怪:例如我有一个玩具Rust程序，在其中我试图越界访问数组元素.程序出现紧急情况，$?是101，但是据说它与Network unreachable错误相对应，这没有任何意义.

I've search the google and results are quite strange: e.g. I have a toy Rust program in which I'm trying to access array element out of bounds. The program panics and $? is 101, however it is said to correspond to Network unreachable error, which doesn't make any sense.

推荐答案

程序的退出状态(shell中的$?)与C errno无关.

The exit status of a program ($? in the shell) is unrelated to the C errno.

在C程序中，退出状态通常来自exit的自变量或main的返回值.约定是0表示成功退出(对于shell来说为true)，而其他值则为失败(ir为false).

In a C program, normally the exit status comes from the argument to exit or the return value of main. The convention is that 0 means a successful exit (or true for the shell) and other values are a failure (ir false).

但是，如果程序因接收到信号而死亡，则外壳程序会将$?设置为128加信号号.例如，在出现分段错误(SIGSEGV为11)时，$?将为139.

However if a program died from receiving a signal, the shell sets $? to 128 plus the signal number. For example, on a segmentation fault (SIGSEGV, which is 11), $? would be 139.

要列出信号编号，请运行kill -l.

To list signal numbers, I run kill -l.

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