How do I install a script to run anywhere from the command line?

Walkthrough of making a python script available anywhere:

Make a python script:

cd /home/el/bin
touch stuff.py
chmod +x stuff.py

Find out where your python is:

which python
/usr/bin/python

Put this code in there:

#!/usr/bin/python
print "hi"

Run in it the same directory:

python stuff.py

Go up a directory and it's not available:

cd ..
stuff.py

-bash: stuff.py: command not found

Not found! It's as we expect, add the file path of the python file to the $PATH

vi ~/.bashrc

Add the file:

export PATH=$PATH:/home/el/bin

Save it out, re apply the .bashrc, and retry

source ~/.bashrc

Try again:

cd /home/el
stuff.py

Prints:

hi

The trick is that the bash shell knows the language of the file via the shebang.

Just create ~/bin and put export PATH=$PATH:$HOME/bin in your bashrc/profile. Don't mess with the system, it will bite you back, trust me.

Few more things (relevant to the question but not part of the answer):

The other way export PATH=$HOME/bin:$PATH is NOT safe, for bash will will look into your ~/bin folder for executables, and if their name matches with other executables in your original $PATH you will be surprised by unexpected/non working command execution.
Don't forget to chmod+x when you save your script in ~/bin.
Be aware of what you are putting in your ~/bin folder, if you are just testing something or working on unfinished script, its always better to use ./$SCRIPT_NAME from your CWD to execute the script than putting it under ~/bin.

The best place to put things like this is /usr/local/bin.

This is the normal place to put custom installed binaries, and should be early in your PATH.

Simply copy the script there (probably using sudo), and it should work for any user.