[SOLVED] sub functions not executing

andrew.comly · 07-21-2016, 11:52 PM

Sub functions can not execute.

I would like to use functions to produce the following output

Code:

a/Watermelon
a/Apple
a/Fire-Dragon
a/Papaya
Loop b:
b/Watermelon
b/Apple
b/Fire-Dragon
b/Papaya
Loop c:
c/Watermelon
c/Apple
c/Fire-Dragon
c/Papaya
Loop d:
d/Watermelon
d/Apple
d/Fire-Dragon
d/Papaya
Loop e:
e/Watermelon
e/Apple
e/Fire-Dragon
e/Papaya

=======================================================================
ATTEMPT 01

Code:

#!/bin/bash
#GNU bash, version 4.3.11(1)-release (i686-pc-linux-gnu)

#VARIABLES
	#INITIALIZE
		unset FF i w x y z
		
	#DEFINE
		z=Watermelon
		y=Apple
		x=Fire-Dragon
		w=Papaya

#FUNCTIONS
	f1 ()
	{
		echo="${1}/${z}"
	}
	
	f2 ()
	{
		echo="${1}/${y}"
	}
	
	f3 ()
	{
		echo "${1}/${x}"
	}
	
	f4 ()
	{
		echo "${1}/${w}"
	}
		
bkp ()
{
	for i in `echo $1`; do 
		echo "Loop ${i}:"
		f1 "${i}";
		f2 "${i}";
		f3 "${i}";
		f4 "${i}";
	done
}


FF="a b c d e"

bkp "${FF}"

The results are not ideal, with f1 and f2 not executing:

Code:

$ funcPassStr_SubFuncInForInFunc.sh 
Loop a:
a/Fire-Dragon
a/Papaya
Loop b:
b/Fire-Dragon
b/Papaya
Loop c:
c/Fire-Dragon
c/Papaya
Loop d:
d/Fire-Dragon
d/Papaya
Loop e:
e/Fire-Dragon
e/Papaya

***********************************************************************

In this next attempt, I define the sub functions inside of the function "bkp":

=======================================================================
ATTEMPT 02

Code:

#!/bin/bash
#GNU bash, version 4.3.11(1)-release (i686-pc-linux-gnu)

#VARIABLES
	#INITIALIZE
		unset FF i w x y z
		
	#DEFINE
		z=Watermelon
		y=Apple
		x=Fire-Dragon
		w=Papaya

		
#FUNCTIONS
bkp ()
{
	#SUB-FUNCTIONS
		f1 ()
		{
			echo="${1}/${z}"
		}
		
		f2 ()
		{
			echo="${1}/${y}"
		}
		
		f3 ()
		{
			echo "${1}/${x}"
		}
		
		f4 ()
		{
			echo "${1}/${w}"
		}
	
	for i in `echo $1`; do 
		echo "Loop ${i}:"
		f1 "${i}";
		f2 "${i}";
		f3 "${i}";
		f4 "${i}";
	done
}


FF="a b c d e"

bkp "${FF}"

Results:

Code:

$ funcPassStr_SubFuncInForInFunc.sh 

Loop a:
a/Fire-Dragon
a/Papaya
Loop b:
b/Fire-Dragon
b/Papaya
Loop c:
c/Fire-Dragon
c/Papaya
Loop d:
d/Fire-Dragon
d/Papaya
Loop e:
e/Fire-Dragon
e/Papaya

***********************************************************************

In the next attempt I define the variables x-z w/in the main function bkp:

=======================================================================
ATTEMPT 03

Code:

#!/bin/bash
#GNU bash, version 4.3.11(1)-release (i686-pc-linux-gnu)

#VARIABLES
	#INITIALIZE
		unset FF i w x y z
		
#FUNCTIONS
bkp ()
{
	#VARIABLES
		#DEFINE
			z=Watermelon
			y=Apple
			x=Fire-Dragon
			w=Papaya
	#SUB-FUNCTIONS
		f1 ()
		{
			echo="${1}/${z}"
		}
		
		f2 ()
		{
			echo="${1}/${y}"
		}
		
		f3 ()
		{
			echo "${1}/${x}"
		}
		
		f4 ()
		{
			echo "${1}/${w}"
		}
	
	#MAIN
		for i in `echo $1`; do 
			echo "Loop ${i}:"
			f1 "${i}";
			f2 "${i}";
			f3 "${i}";
			f4 "${i}";
		done
}


FF="a b c d e"

bkp "${FF}"

Results:

Code:

$ funcPassStr_SubFuncInForInFunc.sh 
Loop a:
a/Fire-Dragon
a/Papaya
Loop b:
b/Fire-Dragon
b/Papaya
Loop c:
c/Fire-Dragon
c/Papaya
Loop d:
d/Fire-Dragon
d/Papaya
Loop e:
e/Fire-Dragon
e/Papaya

***********************************************************************
Why do only functions f3 and f4 execute? How can I get f1 and f2 to execute?

astrogeek · 07-22-2016, 12:30 AM

Each function is executing exactly as written in each example.

They all produce the same unexpected result because you copy/pasted the same error into each file.

With that hint, see what you can figure out!

grail · 07-22-2016, 12:52 AM

Nice catch astrogeek ... I had to re-read the examples a few times to spot the issue

pan64 · 07-22-2016, 01:42 AM

additionally you can use set -xv at the beginning of your script to see what's happening
and one more comment:

Code:

# use:
for i in $1; do
# instead of:
for i in `echo $1`; do

HMW · 07-22-2016, 01:59 AM

Quote:

Originally Posted by astrogeek

Each function is executing exactly as written in each example.

They all produce the same unexpected result because you copy/pasted the same error into each file.

With that hint, see what you can figure out!

A-ha! That was actually a pretty hard bug to spot!

A couple of years ago I made a similar error in php. Took me bloody AGES to find.

I second what pan64 said. Insert

Code:

set -xv

at the beginning of your script and you will find this yourself (another hint: the errors are WITHIN the f1 and f2 functions).

Also, my hat is off to the OP. This is a great example of how a question should be written!

Best regards,
HMW

Michael Uplawski · 07-22-2016, 07:18 AM

Quote:

Originally Posted by HMW

Also, my hat is off to the OP. This is a great example of how a question should be written!

That was about the only thing, I wanted to remark. Unable to spot the error I thought of other things.., what's my neighbor doing in this heat working on his roof? BAMM! There is the coding error. In deed, not what I had expected, first.

andrew.comly · 07-22-2016, 08:30 AM

Quote:

Originally Posted by pan64

additionally you can use set -xv at the beginning of your script to see what's happening

I had been using bash -xv, but not in my actual program, yet in the terminal. I would first have to execute "bash -xv" to launch a sub-shell, and from this I had been launching my program. Unfortunately the "bash -xv" sub-shell hardly gives any information at all.

Using "set -xv" right in the programs' script is an outstanding debugging technique, and it looks like I won't have to worry about anymore about going to the trouble of first having to launch that super verbose sub-shell "bash +xv".

Moreover, with "set -xv" you can refine the suspected area of your program with:

Code:

set -xv           #debugging on

suspect cmd1
suspect cmd2
suspect cmd3

set +xv           #debugging off

I'm sure you told me about this before, thanks for reminding me again. I'll definitely put this into my daily repertoire. Better late than never.

andrew.comly · 07-22-2016, 08:36 AM

Quote:

Originally Posted by pan64

# use:

Code:

for i in $1; do

# instead of:

Code:

for i in `echo $1`; do

Thanks very much, writing

Code:

$1

is far more convenient than

Code:

`echo $1`

.

Easier on one's eyes during debugging also!

andrew.comly · 07-22-2016, 08:42 AM

Quote:

Originally Posted by pan64

additionally you can use set -xv at the beginning of your script to see what's happening

Thanks again for this new debugging tool, and after only a few minutes of utilizing this I found the problem.

Now my program outputs the choice results.