If you want a shell script to be executable from Finder then you only need to follow two steps. No additional helper apps are needed; some exist but don't bother.
When the file.command is double-clicked/command-o in Finder, the Terminal will pop up and you'll see the script executed as well as the output.
Note 1: It does not work to symlink a current .sh script and make the symlink end in .command
Here's an example script I use to mount my code repository since I'm having trouble with AutoFS caching and failing to reconnect.
Example File: code_repos.command
#!/bin/sh sshfs adam@svn:/path/to/code_repos/ /Users/adam/ssh_mounts/code_repos -oreconnect,volname=code_repos
Example Terminal.app Output
Last login: Thu Feb 21 01:27:22 on ttys003 You have mail. /Users/adam/Desktop/Scripts/sshfs/code_repos.command ; exit; mosfet:~ adam$ /Users/adam/Desktop/Scripts/sshfs/code_repos.command ; exit; logout [Process completed]
Wherever you put the file, it will run with your home directory (ie: /Users/adam) as the current working directory.
To get around this, use the following line after the #!/bin/sh in your shell script. This will move the current working directory to the directory that contains your command file.
cd "`dirname "$0"`"