using PATH to run scripts from anywhere

Background

I have been looking at setting up a tools folder on my computer so scripts within it can be run from anywhere. Normally, you can only invoke a script like this from either within the folder it is placed, or by specifying the path in which the script resides. To do this we can modify the .bash_profile file, depending on the shell you are using. For example: Here is my current PATH:

/Library/Frameworks/Python.framework/Versions/3.4/bin:/Library/Frameworks/Python.framework/Versions/3.6/bin:/usr/local/bin:/usr/bin:/bin:/usr/sbin:/sbin:/opt/X11/bin

I’ve created a simple script that echos Test to the terminal in:

/Users/Simac/Tools

Tools $ ls
time.sh

when I execute this in my home directory, it is not recognised by the system as the above current PATH does not include my script. The system checks the PATH from left-to-right looking for the file to execute. Each directory is colon separated and if it finds the script in /usr/local/bin it won’t search any further. There is potential for danger here as if some malicious script is placed at the start of the PATH, then it will override a legitimate, similarly named script. For that reason, I would recommend to place the new path at the end (far right of the full PATH). I am using bash as my shell, which can be checked with:

~ $ echo $0
-bash

so the directory is added in ~/.bash_profile
Enter the below:

export PATH="$PATH:/Users/Simac/Tools"

open a new terminal session for the new PATH to take effect or use source ~/.bash_profile

Now you can see the changes have taken effect:

~ $ echo $PATH

/Library/Frameworks/Python.framework/Versions/3.4/bin:/Library/Frameworks/Python.framework/Versions/3.6/bin:/usr/local/bin:/usr/bin:/bin:/usr/sbin:/sbin:/opt/X11/bin:/Users/Simac/Tools

You can see that the new path has been appended to the full PATH. If you wanted to prepend the path, enter the following command:

export PATH="/Users/Simac/Tools:$PATH"

Now we can test our script:

/Users/Simac
~ $ time.sh
Test

The script runs perfectly from our home directory (or anywhere else)