Shell Programming and Scripting

OK,

I know function has to be defined first - in sequence - before it can be used.

So the script has to be build "bottoms -up style, if you pardon my expression.

I am running into a problem reusing function and breaking the sequence.

It would be nice to be able to see the function usage tree as used in script.


Is there such a thing /application ?



Or - will bash complain when I have multiple definitions of a function to keep them in sequence?

I don't understand what you're trying to do. How does having multiple definitions of a function keep anything in sequence?

If you have defined a function more than once, the last function definition command executed for that function will be the one used when that function is invoked.

Yuck, that sounds like a maintenance nightmare.

It is quite common to see a main function at the top a the script. Like this:

Code:

main() {
     foo
     bar
}

foo() {
   # code for foo
}

bar() {
   # code for bar
}

# Pass script arguments into main for argument parsing
main $@

But you still need to keep the functions in the correct order, i.e callee before caller.

There is no need to have the functions in strict order. A function just needs to be known when it is invoked. Hence, if you put all the functions on the top of your script, you can arrange them in any order.

To be honest i prefer Korn shell over bash on any day of the week and twice on Sundays and this (the missing FPATH) is one of the reasons.

Still it is possible to get some sort of order in bash too: put every function in its own separate file, then use the source command to load these at the beginning of the script. This way you can't ever have two functions with the same name because the filesystem has distinct entries.

Note that this only pays off in big script projects. Scripts with 50-100 lines are easy to oversee but once the script gets several thousands of lines it is equally easy to lose track.

I hope this helps.

bakunin

So the bottom like is - I have to clean -up my own mess. O well...

------ Post updated at 11:14 AM -----




Right church wrong pew -

sorry I do not know how my NEW post got here.




OK, I have not got the full grasp of this "standard " input / output /error process.



I have manged to append (two) variables to a file.

I know how to reverse their order using tac.

I can see the "standard output" in terminal. - output from tac.

I like to "send" each line to $1 and $2 respectively. Actually to an array of $, but I'll tackle that later.



I know how to do "while read" , I like to learn more by using tac directly.



Here is the base I have so far , not much.

Code:

echo "$LINENO  reverse  file entries  FIFO "
tac $PWD$DEBUG_DIR$DEBUG_MENU 
#ouputs lines to terminal FIFO 
echo "$LINENO  reverse  file entries  FIFO "

Hi bakunin...

What a neat idea, I like it...
They make similar functions in other scripts effectively redundant.