fs api help

I have a program, and on the startup, I want it to check witha file to see different things, such as :
if it is running
if it is in the middle of executing code

actually, I think that it. I want to do this by, when it starts the the code, it will say if it is executing that code from a variable in another file, or if it is idle.
Now, the problem is the fs api. I have no idea how to use it, and I have found little help to help me here. Mostly its the path it wants. I don't know the correct syntax to put the path as. Also, I want to edit variables in the other file, and then read them upon startup. As I will have multiple variables, how could I do this without mixing up the variables?

A little more info in the program:
I am making a strip mining program, with the turtle having one large main branch, and stemming out, with pneumatic pipes sending the junk out, and sending more pipes and torches to it. I want to control it with a computer remotely, telling how much to expand it, or to just stop.

Any suggestions on how to do this better would be much appreciated.

You won't use fs API to load a variable from an other file, since you can't, the most you could do is have a different file for every variable you want, such as

file = fs.open("file","r") -- "file" [inside the ()] is the file name, in this case the file with the specificity variable you want, the file MUST exist.
local {Variable} = file.readLine()

This only works if you want to have a file for every variable that you will use. Or you might want to use

os.loadAPI("FILENAME")

This will allow you to load a multiple variable from an other file.
Then just simply use the variables, but I usually get errors that way, so I suggest making a different file for every variable with fs API.

loadstring() might help you.
It can be a bit mean to people who do not understand meta tables very well though.

Also, I am not sure why you would want to use a file, and not just send code over rednet?

I am not exactly sure what you are trying to do.

Well neither of you have really hit on the mark with loading variables from files (and also, metatables have nothing to do with this). You can use textutils.serialize/textutils.unserialize to make storing variables in files easier, but there are literally infinite ways to do so.

What textutils.serialize does is convert a table into string form, meaning that its easy to save a large number of variables to a single file. textutils.unserialize reverses the operation. Here's an example:

--serializing
local programStatus = {
  running = true;
  programName = "/testProg";
  other_info = 5;
}

local f = fs.open("save_info", "w")
f.write(textutils.serialize(programStatus))
f.close()

And unserializing it:

local f = fs.open("save_info", "r")
local content = f.readAll()
f.close()
content = textutils.unserialize(content) --It's a table again
print(content["running"]) --Prints "true"

If you only need to save one variable to a file, you could just use normal comparison like so:

local f = fs.open("save_info", "w")
f.write("running:true")
f.close()

--And then on your program ending you could do this
local f = fs.open("save_info", "w")
f.write("running:false")
f.close()

local f = fs.open("save_info", "r")
local content=f.readAll()
f.close()
if content=="running:true" then
  print("The program is running!")
else
  print("The program is not running.")
end

Another thing you could do is just check that a file exists:

local f = fs.open(".currentProgram", "w")
f.close()

--And on the close
fs.delete(".currentProgram")

if fs.exists(".currentProgram") then
  print("It's running!")
end

If you actually want a boolean value and not a string representation of it, tostring and loadstring will serve your purposes.

local fileContent = "true" --Pretend I saved the boolean to a file and loaded it alread with f.readAll() or something
local bool_value = loadstring(fileContent)
print(type(bool_value)) --Outputs "boolean"