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What are the most inscrutable lines of $SHELL you've ever written? (programming.dev)

submitted 1 year ago* (last edited 1 year ago) by gamma to c/shell

31 comments fedilink hide all child comments

I'm sure some of you have absolute monstrosities of sigils (I know I do, in my .zshrc alone). Post them without context, and try and guess what other users's lines are. If you want to provide context or guess, use the markdown editor to spoiler-tag your guesses and explanations!

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[–] gamma 2 points 1 year ago* (last edited 1 year ago) (13 children)

Nice! This one was probably the most likely to be found, I actually got this trick from somewhere else online before I understood what it was doing. If you're curious, I've got a few other lines of nested Zsh expansions I picked out but didn't post.

[–] varsock 1 points 1 year ago (12 children)

curious to see if AI can decipher? Certainly! bonus that we get so see potentially beneficial shell

[–] gamma 1 points 1 year ago* (last edited 1 year ago) (11 children)

Here's all the ones I was considering. I only posted the first two here. I'll add the explanations later.

ZDOTDIR="${${(%):-%x}:P:h}"                                              # posted 
reply=( ${(M)dirs:#*/$~pattern}(Noe['REPLY=${(l[3][0])#REPLY:t}'][1]) )  # posted
typeset -a $1=("${(@ps[$2])"${2:-"$(<&0)"}"}")
local d=("${(@s[/])${(%):-%~}}")
print -rn $termcap[sc]${termcap[ch]//(\%i|\%p1|\%d)}$termcap[ct]${(j::)s}$termcap[rc]
[ "${(Oa@)argv[1,-2]}" "${argv[-1]//(#m)[\[\]]/${(#)$((6 ^ #MATCH))}}"   # this one is definitely not useful
set -- "${@[0,eoo]:/(#m)^-*/${MATCH:a}}" "${@[eoo+1,-1]:a}"

[–] varsock 1 points 1 year ago (1 children)

local d=("${(@s[/])${(%):-%~}}")

spoiler

The given shell script is written in the Zsh shell syntax. It initializes a local array variable d with the expansion of a string. Let's break it down step by step:

local d=: This line declares a local variable d. The local keyword is used to define variables with local scope, meaning they are only accessible within the current scope, such as within a function or a block of code.
"${(%):-%~}": This part of the script performs string expansion and substitution to populate the array d.
- %~ is a special parameter expansion in Zsh that expands to the current working directory (tilde expansion).
- (%): is another parameter expansion flag that performs splitting and globbing on the value obtained from %~. It splits the resulting string into separate elements based on the / delimiter and performs globbing (filename expansion) on each element.
  
  For example, if the current working directory is /path/to/some/directory, then %~ expands to /path/to/some/directory, and (%): splits it into individual components: path, to, some, and directory. If there are any glob patterns present, such as * or ?, they would be expanded as well.
("${(@s[/])${(%):-%~}}"): This part surrounds the expanded string with parentheses to create an array and stores it in the variable d. The (@s[/]) syntax is an array flag in Zsh that splits the resulting string into separate elements based on the / delimiter. Each element represents a directory component obtained from the %~ expansion.

In summary, this script initializes the local array variable d with the directories present in the current working directory's path. Each directory is stored as a separate element in the array d.

[–] gamma 1 points 1 year ago

It may have gotten some details wrong, but the summary is spot-on.

Corrections

(%) enables prompt expansion. %~ is a string, which when prompt expanded, is $PWD with tilde expansion.

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