Directory tree with links

We write a Bash script for building a directory tree for a repository in the Markdown file. We use only Bash builtin tools and basic Linux software — ls, sed, tr and printf — without additional programs. The obtained file DIRECTORY_TREE.md is useful in the web-interface to navigate through the objects of the repository.

We create a recursive function and use it to bypass all files and directories of the repository, excluding the list from .gitignore — we build a directory structure in the form of a tree. We output the elements as links <a>, collapse folders with one nested element into one line, place the constructed tree in a container <pre> and add the header — as a result, we get a short and concise Markdown file with links.

#!/bin/bash
# directory tree with links
function directory_tree {
  # arguments
  local path="$1"
  local head="$2"
  local tail="$3"
  # get directory contents
  if [ -d "$path" ]; then
    # first uppercase letters, then lowercase, first directories, then files
    ls_sorted="LC_COLLATE=C ls -A --group-directories-first $exclusions $path"
    # sorted array of files and directories
    local list && readarray -t list < <(eval "$ls_sorted")
    # length of array
    local size=${#list[@]}
    # skip empty directory
    [ "$size" == 0 ] && return
  fi
  # prefix of current element, collapse singletons into one line
  [ "$4" == "one" ] && printf '%s' "/" || printf '\n%s' "$head"
  # current element of the tree — relative hyperlink
  printf '%s' "<a href='${path#*/}'>${path##*/}</a>"
  # recursive calls for subdirectories
  if [ -d "$path" ]; then
    local i # counter
    for ((i = 0; i < size; i++)); do
      if ((size == 1)); then
        directory_tree "$path/${list[$i]}" "$tail" "$tail" "one"
      elif ((i < size - 1)); then
        directory_tree "$path/${list[$i]}" "$tail├─ " "$tail│  "
      else
        directory_tree "$path/${list[$i]}" "$tail└─ " "$tail   "
      fi
    done
  fi
}
# line of exclusions for "ls" from the list of untracked files ".gitignore"
exclusions="-I'.git' $(sed -E "s|^(.*)$|-I'\1'|" .gitignore | tr '\n' ' ')"
# place the tree in a container, add a header and output to a file
printf '%s\n' "## Directory tree" "" "<pre>" \
  "$(directory_tree . | grep '\S')" "</pre>" >DIRECTORY_TREE.md