编程提领/解决在bash别名 [英] Programmatically dereference/resolve aliases in bash

问题描述

我需要确定哪些命令外壳别名解析为在bash，编程;即，我需要编写，将采取一个名字可能指的是一个别名，并返回真正的bash函数命令，它最终是指，通过别名链递归适用。

I need to determine which command a shell alias resolves to in bash, programmatically; i.e., I need to write a bash function that will take a name potentially referring to an alias and return the "real" command it ultimately refers to, recursing through chains of aliases where applicable.

例如，下面给出的别名：

For example, given the following aliases:

alias dir='list -l'
alias list='ls'

在我的功能就是 dereference_alias ，

dereference_alias list    # returns "ls"
dereference_alias dir     # also returns "ls"

有一些内置的我不知道，这是否整齐，否则我就辞职自己刮别名？

Is there some builtin I don't know about that does this neatly, or shall I resign myself to scraping the output of alias?

推荐答案

下面就是我正在做的，虽然我不知道这是最好的方式：

Here's how I'm doing it, though I'm not sure it's the best way:

dereference_alias () {
  # recursively expand alias, dropping arguments
  # output == input if no alias matches
  local p
  local a="$1"
  if [[ "alias" -eq $(type -t $a) ]] && p=$(alias "$a" 2>&-); then
    dereference_alias $(sed -re "s/alias "$a"='(\S+).*'$/\1/" <<< "$p")
  else
    echo $a
  fi
}

这里主要的缺点是我靠 SED ，和我的别名将任何参数来停止在第一个空间，希望没有别名将永远点一个程序当中，由于某些原因，有空格在其名称（即别名badprogram ='A \\非常\\坏\\程序 - 有些参数的），这是一个合理的足够的假设，但仍。我认为，至少在整个 SED 部分可以通过或许真的杠杆的bash自己的解析/分裂/命令行的标记化所取代，但我不知道从哪里开始。

The major downsides here are that I rely on sed, and my means of dropping any arguments in the alias stops at the first space, expecting that no alias shall ever point to a program which, for some reason, has spaces in its name (i.e. alias badprogram='A\ Very\ Bad\ Program --some-argument'), which is a reasonable enough assumption, but still. I think that at least the whole sed part could be replaced by maybe something leveraging bash's own parsing/splitting/tokenization of command lines, but I wouldn't know where to begin.

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