Add an install "one-liner" to the README.

Also fix a bug when running build_and_install.sh from a directory other
than the root of the project.

README.md

@@ -47,18 +47,37 @@ Background Music Device. You can create the aggregate device using the Audio MID
 
 ## Install
 
-No binaries yet, but building should take less than a minute. To build and install everything do the following:
+No binaries yet (working on it) but building should take less than a minute.
+
+<table>
+<tr><td>⚠️</td>
+<td>Unfortunately, <strong>it won't build if you don't have Xcode installed</strong> because xcodebuild doesn't work on its own anymore. If you don't mind a 4GB download, you can <a href="https://developer.apple.com/xcode/download/">get Xcode here</a>.</td>
+</tr></table>
+
+If you're comfortable with it, you can just paste the following at a Terminal prompt.
+
+[//]: # (Uses /bin/bash instead of just bash on the off chance that someone has a non standard Bash in their $PATH, but)
+[//]: # (it doesn't do that for Tar or cURL because I'm fairly sure any versions of them should work here. That said,)
+[//]: # (build_and_install.sh doesn't call things by absolute paths (yet?) anyway.)
+[//]: # ( )
+[//]: # (Uses "gzcat - | tar x" instead of "tar xz" because gzcat will also check the file's integrity. (Gzip files)
+[//]: # (include a checksum.))
+```shell
+(set -eo pipefail; URL='https://github.com/kyleneideck/BackgroundMusic/archive/master.tar.gz'; \
+    cd $(mktemp -d); echo Downloading $URL to $(pwd); curl -qfL# $URL | gzcat - | tar x && \
+    /bin/bash BackgroundMusic-master/build_and_install.sh && rm -rf BackgroundMusic-master)
+```
+
+Otherwise, to build and install everything, do the following:
 
 - Clone or [download](https://github.com/kyleneideck/BackgroundMusic/archive/master.zip) the project
 - If the project is in a zip, unzip it
 - [Go to the folder of the project](https://github.com/0nn0/terminal-mac-cheatsheet/wiki/Terminal-Cheatsheet-for-Mac-(-basics-)#core-commands) on your terminal
-- Run the following the command: `./build_and_install.sh`.
+- Run the following the command: `/bin/bash build_and_install.sh`.
-
-Unfortunately, **it won't build if you don't have Xcode installed** because xcodebuild doesn't work on its own anymore.
 
 The script restarts the system audio process (coreaudiod) at the end of the installation, so you might want to pause any apps playing audio.
 
-Additional detailed installation instructions can be found in the Wiki: https://github.com/kyleneideck/BackgroundMusic/wiki
+Additional detailed installation instructions can be found on [the Wiki](https://github.com/kyleneideck/BackgroundMusic/wiki/Installation).
 
 ## Uninstall
 

build_and_install.sh

@@ -32,6 +32,9 @@ IFS=$'\n\t'
 # Subshells and function inherit the ERR trap
 set -o errtrace
 
+# Go to the project directory.
+cd "$( dirname "${BASH_SOURCE[0]}" )"
+
 error_handler() {
     local LAST_COMMAND="${BASH_COMMAND}" LAST_COMMAND_EXIT_STATUS=$?
 
@@ -369,9 +372,6 @@ log_debug_info() {
 # Register our handler so we can print a message and clean up if there's an error.
 trap 'error_handler ${LINENO}' ERR
 
-# Go to the project directory.
-cd "$( dirname "${BASH_SOURCE[0]}" )"
-
 parse_options "$@"
 
 # Warn if running as root.