Partially mimic the `tree` command via Bash in macOS, Synology Disk Station Manager (DSM), et al.

faux_tree.sh

#!/usr/bin/env bash
#
# Faux "tree" function in macOS, Synology Disk Station Manager (DSM), et. al.
# Comparable in output to Steve Baker's "tree" utility:
# http://mama.indstate.edu/users/ice/tree/
#
# Add function to: /Users/foo/.profile, or: .bash_profile,
# then refresh the profile with: source .profile or: source .bash_profile
# 
# Inspired by this thread: https://superuser.com/questions/359723/mac-os-x-equivalent-of-the-ubuntu-tree-command

##########################################################################
# Recursive directory/file listing of present working directory (PWD),
# with summary count of directories and files.
# Argument: 
#   Directory of interest,
#     e.g.: tree /Users/foo/foo_dir
# Output:
#   Recursive directory/file listing of named directory,
# 
# Argument:
#   Directory of interest, with user-defined level of resursive depth,
#     e.g.: tree /System/Library 2
# Output:
#   Recursive directory/file listing of named directory, stopping at
#   user defined depth of recursion, e.g. 2
##########################################################################

tree () {
    [ -n "$2" ] && local depth="-maxdepth $2";
    find "${1:-.}" "${depth}" -print 2> /dev/null | sed -e 's;[^/]*/;|____;g;s;____|; |;g'
}