Paths

Basics

The dirname command

Get the parent directory of a file or directory.

dirname PATH

$ dirname foo/bar
foo

The path does not have to exist as this is a string operation.

The realpath command

Expand a relative path to a full path - resolving symlinks. The path must be valid.

Works on macOS or Debian - requires coreutils.

REALPATH(1)

NAME
       realpath - print the resolved path

SYNOPSIS
       realpath [OPTION]... FILE...

DESCRIPTION
       Print the resolved absolute file name; all but the last component must exist

Example:

$ realpath Documents/mono.conf
/home/michael/Documents/mono.conf

Given that ~/bin is a symlink, this command will resolve it by default.

$ realpath ~/bin/
/home/michael/repos/shell-dev-setup/bin

To leave symlinks unresolved:

$ realpath -s ~/bin
/Users/mcurrin/bin

Warning: If you run cd in a script then you will change the working directory and then realpath will be relative to that, not the original working directory.

Working directory

Get the current working directory - where the commands or scripts are run from, not where they are located.

Print value:

pwd

Use in a string:

echo "You are here: $PWD"
echo "You are here: $(pwd)"

As an approximation, the current working directory and relative path to a script can be combined to a full path.

$PWD/$0

However, it is safer using one of the approaches covered next.

Get path of a script within a script

Note that getting the current directory with pwd will give the working directory of the user. If a script is not the the working directory, then you need something more precise. If you want to get the directory where a script is in, from inside the script, use this.

File path

The path to a script from within a script. Note that $0is the relative path to current script and the working directory will be prepended to it.

realpath $0

SCRIPT_PATH=$(realpath $0)

For script ~/foo/bar.sh, printing that variable:

/Users/my-user/foo/bar.sh

From top answer on SO.