Re: Bash – ”Sourcing” script from another script

[Johnny Rosenberg]

2015-01-06 14:33 GMT+01:00 Karl Auer <kauer at biplane.com.au>:

> On Mon, 2015-01-05 at 18:16 +0100, Johnny Rosenberg wrote:
> > Another idea I had, before I read this, was four scripts:
> > MainScript.sh
> > CalculateVariables.sh
> > Script1.sh
> > Script2.sh
> >
> > MainScript.sh would look something like this:
> > #!/bin/bash
> >
> > CalculateVariables.sh
> > Script1.sh
> > Script2.sh
> > MoreStuff here or where ever suitable.
> >
> > Could that be a reasonable approach?
>
> This runs the separate scripts from inside a main script; it does not
> source them. The variable values will not be passed on.
>

Yes, I just saw that, and that was NOT what I intended to write, I don't
know what happened there… some kind of confusion, I guess…

This is what I meant:
#!/bin/bash

source CalculateVariables.sh
source Script1.sh
source Script2.sh
More Stuff here or where ever suitable.

Sorry that my brain didn't work…


> > Script1.sh and Script2.sh could have commants that tells the reader that
> > variables are declared and/or calculated in CalculateVariable.sh and that
> > MainScript.sh starts all the other scripts, just to make it easier to
> > follow.
>
> If you will never run Script1 and Script2 separately, then you should
> create a single script out of them. You will then only have to calculate
> the variables once, so might as well incorporate that nto the same
> single script.
>
> If the process of calculating the variables is independently useful
> (i.e., there may one day be a Script3 that also has to calculate the
> same variables),


Might happen, but not planned.


> or if you need to be able to run Script1 and Script2
> independently of each other, then make CalculateVariables into an
> independent file and source it from inside the other two.
>
> If running CalculateVariables as a standalone script is pointless, you
> can (and should) prevent that happening by NOT making the first line
> "#!/bin/sh".
>

So running a script with source means that the ”#!/bin/sh” (or in my case
”#!/bin/bash”) in MainScript.sh goes for the sourced script too,
automatically?
Does this mean that you can't source, for instance a Python script from a
bash script? Or does omitting that line only mean ”nothing is changed, keep
going”?


>
> If running it without the proper preparation provided by Script1 or
> Script2 is actually dangerous, and you really don't want that to happen,
> you can do something like have a secret variable that you set in calling
> scripts; if Calculatevariables doesn't see that variable, it refuses to
> run. It won't stop someone who is determined to run it, but it will at
> least force them to be very deliberate about doing so - no-one will run
> it by mistake.
>

Good point. Thanks.
And thanks for the other good points as well.


Kind regards

Johnny Rosenberg
ジョニー・ローゼンバーグ


> Regards, K.
>
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