如何从已经ALREADY运行的进程捕获stdout

本文介绍了如何从已经ALREADY运行的进程捕获stdout的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！ 问题描述

我有一个运行cron工作，将要一段时间，我想查看其stdout。我不知道这个过程是由cron启动的事实是多么重要，但我想我会提到它。这是在OSX所以，我没有访问像... / proc / [pid] / ...，或truss或strace的东西。使用IO重定向执行的建议（例如 script> output& tail -f output ）不可接受，因为此进程1）已在运行，以及2） t重定向停止/重新启动。如果有通用的解决方案，将工作在各个Unices，这将是理想的，但具体来说，我想在Mac上完成这个现在。

I have a running cron job that will be going for a while and I'd like to view its stdout. I don't know how important the fact that the process was started by cron is, but I figure I'd mention it. This is on OSX so, I don't have access to things like... /proc/[pid]/..., or truss, or strace. Suggestions of executing with IO redirection (e.g. script > output & tail -f output) are NOT acceptable, because this process is 1) already running, and 2) can't be stopped/restarted with redirection. If there are general solutions that will work across various Unices, that'd be ideal, but specifically I'm trying to accomplish this on a Mac right now.

推荐答案

OSX的真正解决方案

将以下函数写入您的〜/ .bashrc 或〜/ .zshrc 。

capture() { sudo dtrace -p "$1" -qn ' syscall::write*:entry /pid == $target && arg0 == 1/ { printf("%s", copyinstr(arg1, arg2)); } ' }

用法：

example@localhost:~$ perl -e 'STDOUT->autoflush; while (1) { print "Hello\n"; sleep 1; }' >/dev/null & [1] 97755 example@localhost:~$ capture 97755 Hello Hello Hello Hello ...

https： //github/mivok/squirrelpouch/wiki/dtrace

注意：

您必须在El Capitan或更高版本上禁用 dtrace 限制。

You must disable dtrace restriction on El Capitan or later.

csrutil enable --without dtrace