我如何获得＆QUOT; previous执行命令＆QUOT;在bash脚本？ [英] How do I get "previous executed command" in a bash script?

问题描述

我使用多个的bash会话，我想跟踪历史，从所有的人都在一个文件中（我不在乎它是由多个会话复用的，我可以随时把会话标识符在它的前面。 ）我试图做

I use multiple bash sessions, and I want to keep track of history from all of them in one file (I don't care that it is multiplexed from multiple sessions, I can always put a session identifier in front of it.) I have tried doing

shopt -s histappend

和还加入

history -a 

到 $ PROMPT_COMMAND 变量。但没有人真正为我工作，我不明白为什么他们不工作（他们的行为非常不确定性，据我可以告诉...有时他们从复多个会话的命令，有时他们不）。

to the $PROMPT_COMMAND variable. But none of them really work for me, and I don't understand why they don't work (they behave very non-deterministically as far as I can tell... sometimes they multiplex commands from multiple sessions, sometimes they don't).

这个问题的目标是探索另一种方法来保持历史，从所有会话，在那里我可以控制我写的历史。我们的想法是存储previous命令，在一个shell变量，然后回显该变量的历史记录日志文件 PS1 变量的定义中。

The goal of this question is to explore an alternate way to keep history from all sessions, where I can control what I write to the history. The idea is to store "previous command" in a shell variable and then echo that variable to a history-log file inside the definition of PS1 variable.

现在的问题是：我得到一个shell变量previous执行命令怎么办。我知道我可以执行回音！ ＆GT;＆GT; LOGFILE.TXT 交互式bash命令将其记录到日志文件。但我怎么做到这一点的脚本文件（或.bashrc文件）？

The question is: How do I get the "previous executed command" in a shell variable. I know I can execute echo !! >> logfile.txt in interactive bash session to record it to a log file. But how do I do this in a script file (or .bashrc file)?

我曾尝试

PROMPT_COMMAND="PC=$_;"
PREVIOUS_COMMAND=$(echo $PC)  # $_ only gives the last argument of previous command
export PS1="[\u@\h \w] [$PREVIOUS_COMMAND $(echo $_) $_] $ "

但这些都不工作。

But none of this works.

感谢您的时间，
〜瑜伽士

Thanks for your time, ~yogi

推荐答案

类似

fc -ln -1

应该工作。这就是说，你很可能运行到并发访问的问题（阅读：多壳覆盖彼此的历史），你可能无法用手做得更好

should work. That said, you're probably running into concurrent access issues (read: multiple shells overwriting each others' history) and you may not be able to do any better by hand.

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