Add a bash script to path

Try this:

• Save the script as apt-proxy (without the .sh extension) in some directory, like ~/bin.
• Add ~/bin to your PATH, typing export PATH=$PATH:~/bin
• If you need it permanently, add that last line in your ~/.bashrc. If you're using zsh, then add it to ~/.zshrc instead.
• Then you can just run apt-proxy with your arguments and it will run anywhere.

Note that if you export the PATH variable in a specific window it won't update in other bash instances.

You want to define that directory to the path variable, not the actual binary e.g.

PATH=$MYDIR:$PATH

where MYDIR is defined as the directory containing your binary e.g.

PATH=/Users/username/bin:$PATH

You should put this in your startup script e.g. .bashrc such that it runs each time a shell process is invoked.

Note that order is important, and the PATH is evaluated such that if a script matching your name is found in an earlier entry in the path variable, then that's the one you'll execute. So you could name your script as apt-get and put it earlier in the path. I wouldn't do that since it's confusing. You may want to investigate shell aliases instead.

I note also that you say it works fine from your current directory. If by that you mean you have the current directory in your path (.) then that's a potential security risk. Someone could put some trojan variant of a common utility (e.g. ls) in a directory, then get you to cd to that directory and run it inadvertently.