Get an absolute path to a folder that doesn't exist yet [bash]

Question

Trying to make a bash script (on mac) that creates a folder then runs a bunch of scripts in that folder. I want to echo the absolute path to folder and prompt user to confirm before taking action.

The script takes a relative path as an argument, how do I convert to an absolute path before creating the folder?

!/bin/bash
if [[ $# -eq 0 ]] ; then
  echo 'Whoa! You dont want to do that! you need to tell me where to put it'
  exit 0
fi

ORG_DIR=$(pwd)
#here I want to get path before making directory, I've only figured out how to do after.
mkdir ../$1
cd ../$1
NEW_DIR=$(pwd)

echo "Running scripts in"
echo $NEW_DIR
read -p "Are you sure? (y/n) " -n 1 -r
if [[ ! $REPLY =~ ^[Yy]$ ]]
then
   # run a bunch of scripts
fi

How do I get the absolute path of NEW_DIR before making it?

Note: Platform is OSX, I don't need to support other 'nix variants.

EDIT: Sat, 29

I realized that in an effort to trim the question down to essential details only, I trimmed to much, my apologies.

This script exists in (for example sake)

/Documents/git/ProjectGenerator

I intend the script to generate a project in (or whatever path is entered)

/Documents/git/NewProject

It runs a combination of npm scripts, and copying files from

/Documents/git/ProjectGenerator

The rest of the script works fine now, however I recently accidentally hit enter on the wrong dir. Since this script is intended for my use only (and not sudo), I'm trying to add a sanity check, not a security check to the beginning of the script. Must type Y and enter after looking at the dir.

I'm trying to get an absolute path and what I'm getting is

/Documents/git/ProjectGenerator/../NewProject

I'm trying to get it to echo

/Documents/git/NewProject

prior to creating the directory. (sometimes the path is far more complex)

In node we have path.resolve(path) In php or c its realpath(path)

I cant seem to find an equivalent command in osx bash, is there one? or do I need to parse the string?

Answer 1

You want to change to the previous directory with .. and that's causing problems finding out the absolute path of your new directory (named $1 in your script, I'll call it $new_directory_name here) that will be ../$new_directory_name.

Before doing any cd or mkdir, I'd use the basename command to show the original directory's ($PWD's) absolute path, then append $new_directory_name to it, like this:

echo $(dirname $PWD)/$new_directory_name

(or replace the $(...) command substitution with backticks `...` (they display funny on stackexchange sometimes - see the Command Substitution section of man bash

I believe you could just use bash's Parameter Expansion (also in man bash) on $PWD instead of basename like this:

 echo ${PWD%/*}/$new_directory_name

---

Examples

$ new_directory_name=newdir
$ pwd
/tmp/testdir
$ echo ${PWD%/*}/$new_directory_name
/tmp/newdir
$ echo $(dirname $PWD)/$new_directory_name
/tmp/newdir

---

Like user912264 mentions, you might consider checking whether .. is a writable directory (with stat -c %a or %A), or if you're already in / then cd .. doesn't go anywhere new, or just watch for errors from mkdir, like

mkdir ... || { echo mkdir ERROR exiting; exit; }

Answer 2

From this comment on stack overflow https://stackoverflow.com/questions/284662/how-do-you-normalize-a-file-path-in-bash#comment81662652_284671

I came to the conclusion coreutils (which I already had installed) has the greadlink command which has the functionality I need.

NEW_DIR=$(greadlink -f ../$1)

EDIT 1:

#!/bin/bash
if [[ $# -eq 0 ]] ; then
  #simple check to ensure enter was not accidently pressed without directory specified
  echo 'Whoa! You dont want to do that! you need to tell me where to put it';
  exit 0
fi

ORG_DIR=$(pwd)
#here I want to get path before making directory, I've only figured out how to do after.
NEW_DIR=$(greadlink -f ../$1)

echo "Running scripts in"
echo $NEW_DIR
read -p "Are you sure? (y/n) " -n 1 -r
if [[ $REPLY =~ ^[Yy]$ ]]
then

  cp -r $ORG_DIR/skeleton $NEW_DIR

  cd $NEW_DIR

  #init the project with default answers.
  yarn init -y

  #add dev scripts
  yarn add --dev webpack webpack-cli babel-loader @babel/preset-react @babel/core @babel/preset-env webpack-dev-server css-loader sass-loader node-sass style-loader file-loader url-loader redux-devtools eslint eslint-plugin-react babel-eslint

  #add production scripts
  yarn add react react-dom react-hot-loader react-redux redux redux-saga redux-socket.io socket.io

fi