That's a very insightful question! To understand how export affects the PATH variable, let's first look at what PATH and export do individually.
1. What is the $PATH variable?
The PATH is an environment variable. It is a list of directories (separated by colons) that the shell searches through when you type a command. For example, when you type ls, the shell looks through the folders listed in your PATH until it finds the ls program.
2. How export works
By default, if you create a variable in your shell, it is a local variable. This means it only exists inside that specific terminal window and isn't shared with any programs or scripts you start from that terminal.
When you use export, you are "promoting" that variable to an environment variable. This ensures that any child processes (new scripts, programs, or sub-shells) started from your current shell will also know about that variable.
3. Combining them: Updating your PATH
When you want to add a new folder (e.g., /home/labex/my_tools) to your PATH so you can run your own scripts from anywhere, you usually run a command like this:
export PATH=$PATH:/home/labex/my_toolsHere is what happens:
PATH=: You are re-assigning the value of the PATH variable.$PATH: This includes the current list of directories so you don't lose the standard ones (like/binor/usr/bin).:/home/labex/my_tools: This appends your new folder to the end of the list.export: This makes sure that every program you run from this moment on knows about this updated list.
Summary
Without export, if you just did PATH=$PATH:/new/folder, your current shell might find commands there, but if you ran a shell script, that script wouldn't see the update. export makes the change "global" for the remainder of that session.
Does that help clarify the connection between the two?
