appify — create the simplest possible Mac app from a shell script (adds an application icon)

appify.sh

#!/bin/bash

if [ "$1" = "-h" -o "$1" = "--help" ]; then cat <<EOF
appify v3.0.0 for Mac OS X - http://mths.be/appify
Creates the simplest possible Mac app from a shell script.

Appify takes a shell script as its first argument:

    `basename "$0"` my-script.sh

Note that you cannot rename appified apps. If you want to give your app
a custom name, use the second argument:

    `basename "$0"` my-script.sh "My App"

Copyright (c) Thomas Aylott <http://subtlegradient.com/>
Modified by Mathias Bynens <http://mathiasbynens.be/>
Modified by Andrew Dvorak <http://OhReally.net/>
EOF
exit; fi

# OSX_VERSION is currently unused, though knowing this may help, since the
# GenericApplicationIcon.icns file may be located elsewhere pre-10.6.x
OSX_VERSION=`sw_vers -productVersion`

APPNAME=${2:-$(basename "$1" ".sh")}
DIR="$APPNAME.app/Contents"

if [ -a "$APPNAME.app" ]; then
	echo "$PWD/$APPNAME.app already exists :("
	exit 1
fi

mkdir -p $DIR/{MacOS,Resources}

# Copy Apple's GenericApplicationIcon to our application.
# - TODO: provide command-line options for specifying an icon to use
#         (maybe even allow the user to specify an)
cp "/System/Library/CoreServices/CoreTypes.bundle/Contents/Resources/GenericApplicationIcon.icns" "$DIR/Resources/$APPNAME.icns"

cp "$1" "$DIR/MacOS/$APPNAME"
chmod +x "$DIR/MacOS/$APPNAME"

cat <<EOF > $DIR/Info.plist
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE plist PUBLIC "-//Apple Computer//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
<plist version="1.0">
<dict>
	<key>CFBundleExecutable</key>
	<string>$APPNAME</string>
	<key>CFBundleGetInfoString</key>
	<string>$APPNAME</string>
	<key>CFBundleIconFile</key>
	<string>$APPNAME</string>
	<key>CFBundleName</key>
	<string>$APPNAME</string>
	<key>CFBundlePackageType</key>
	<string>APPL</string>
</dict>
</plist>
EOF

echo "$PWD/$APPNAME.app"

Missing -o -z "$1" in your line 3, before ].

And this script breaks when apps name have spaces in it, whereas the original version was robust in this matter.
See instructions:

Note that you cannot rename appified apps. If you want to give your app
a custom name, use the second argument:
    appify my-script.sh "My App"

To fix errors for app name with spaces:

@@ -34,1 +34,1 @@
- mkdir -p $DIR/{MacOS,Resources}
+ mkdir -p "$DIR"/{MacOS,Resources}
@@ -44,1 +44,1 @@
- cat <<EOF > "$DIR/Info.plist"
+ cat <<EOF > $DIR/Info.plist

Anyone know how to make the appify'd app appear in the ⌘-tab application switcher, display the namenext to the  in the top left and show up in the dock? My app runs fine, but it's hard to go back and forth to the app once the window loses focus without a dock icon or ⌘-tab'ing to it.

This screenshot shows this behavior: http://c.b0.io/gfGK The appify'd app is active and has focus, but does not have it's name in the top left corner of the desktop and does not show up in the application switcher. Not pictured is the lack of a dock icon. (the application switcher is faded because it was hard to get a screenshot while ⌘-tab'ing). The app is a shell script that calls a Java GUI app, in case that matters.

You can’t open the application “exec” because PowerPC applications are no longer supported.

such a problem appear

yvanin commented on Jul 26 in https://gist.github.com/mathiasbynens/674099 solved the problem "You can’t open the application “exec” because PowerPC applications are no longer supported." by the following method:
It started working (OS X 10.11.2) when I changed #!/bin/bash to #!/usr/bin/env bash at the first line of my .sh script

And you have to make sure that your original script has similar lines to set up the environment

!/bin/bash

Otherwise, you will have to go into $APPNAME.app/Contents/MacOS/$APPNAME and add the environment line at the top of the script.

I forked this and added option-parsing, overridable icons file, and some other bits: https://gist.github.com/oubiwann/453744744da1141ccc542ff75b47e0cf