Empirical test of bash variable scope: main calls function, which calls deeper function #bash

Empirical_test_bash_variable_scope_within_nested_functions.sh

##########################################################################################
#!/usr/bin/env bash
#
#	Script to determine empirically the extent to which a variable set in a script or
#		function can be seen by a hierarchically related function or script 
#	Specifically, (a) main script calls (b) function level1(), which calls
#		function level2(). (No arguments are used in any function call.)
#	Scalar variables are set in each component prior to any function call:
#		Main script sets $set_in_main_x, for x ∈ {A,B,C}
#		Function level1() sets $set_in_level_1_x, for x ∈ {A,B,C}
#		Function level2() sets $set_in_level_2_x, for x ∈ {A,B,C}
#	When each of the two functions is called, it looks to see whether it can see the
#		variables in the component(s) above it.
#	When control returns to the main script or level1(), it checks to see whether it can
#		variables set in the returning function.
#	Each function also attempts to change a value in the script/function above it that had
#		set by the calling entity.
#		E.g., $set_in_main_B was first set in main, and then re-set by level(1).
#	The same exercise is performed with arrays (rather than a scalar variable).
#
#	Results of test:
#		Summary:	Every component could see/change every variable in every other component
#					Arrays were seen, and could be changed, as much as scalars
#		Specifically:
#			Both functions could see/change the variable set in Main: set_in_main_A="543"
#			Main could see the variables set in level1() and level2(), e.g.,
#				set_in_level_1_A? 666
#				set_in_level_2_A? 965
#			level1() could see the values set in level2(); e.g., set_in_level_2_A? 965
#
#	Output:
#	In Main, before calling level1()
#	set_in_main_A: 543
#	set_in_main_B: 901
#	set_in_main_C: 444
#	array_set_in_main_A: sd rg
#	array_set_in_main_B: 5y jy
#	array_set_in_main_C: lp ####
#	Calling level1().
#	##############################
#	In Level 1, before calling Level 2
#	Can I see set_in_main_A? 543
#	Can I see array_set_in_main_A: sd rg
#	set_in_level_1_A: 666
#	set_in_level_1_B: 777
#	set_in_level_1_C: 888
#	array_set_in_level_1_A: jk ?B
#	array_set_in_level_1_B: 11 22
#	array_set_in_level_1_C: 33 77
#	##############################
#	In Level 2
#	Can I see set_in_main_A? 543
#	Can I see set_in_level_1_A? 666
#	Can I see array_set_in_main_A: sd rg
#	Can I see array_set_in_level_1_A: jk ?B
#	set_in_level_2_A: 965
#	set_in_level_2_B: 432
#	set_in_level_2_C: 131
#	array_set_in_level_2_A: tag enemy
#	array_set_in_level_2_B: hash bacon
#	array_set_in_level_2_C: tr egg
#	In Level 1, after calling Level 2
#	Can I see set_in_level_2_A? 965
#	Can I see array_set_in_level_2_A: tag enemy
#	set_in_level_1_C: 999
#	##############################
#	In Main, after calling level1()
#	Can I see set_in_level_1_A? 666
#	Can I see set_in_level_2_A? 965
#	Have the functions changed the values that were originally set in main()?
#	set_in_main_A: 543
#	set_in_main_B: 999
#	set_in_main_C: 999
#	array_set_in_main_A: sd rg
#	array_set_in_main_B: 999 999
#	array_set_in_main_C: 999 999

function level1() {

set_in_level_1_A="666"
set_in_level_1_B="777"
set_in_level_1_C="888"

array_set_in_level_1_A=( "jk" "?B")
array_set_in_level_1_B=( "11" "22")
array_set_in_level_1_C=( "33" "77")

echo "##############################"
echo "In Level 1, before calling Level 2"
echo "Can I see set_in_main_A? $set_in_main_A"

echo "Can I see array_set_in_main_A: ${array_set_in_main_A[@]}"

echo "set_in_level_1_A: $set_in_level_1_A"
echo "set_in_level_1_B: $set_in_level_1_B"
echo "set_in_level_1_C: $set_in_level_1_C"

echo "array_set_in_level_1_A: ${array_set_in_level_1_A[@]}"
echo "array_set_in_level_1_B: ${array_set_in_level_1_B[@]}"
echo "array_set_in_level_1_C: ${array_set_in_level_1_C[@]}"

level2

echo "In Level 1, after calling Level 2"
echo "Can I see set_in_level_2_A? $set_in_level_2_A"
echo "Can I see array_set_in_level_2_A: ${array_set_in_level_2_A[@]}"
echo "set_in_level_1_C: $set_in_level_1_C"

#	Modify values in main script
set_in_main_B="999"
array_set_in_main_B=( "999" "999")

}
##############################

function level2() {

echo "##############################"
echo "In Level 2"
echo "Can I see set_in_main_A? $set_in_main_A"
echo "Can I see set_in_level_1_A? $set_in_level_1_A"

echo "Can I see array_set_in_main_A: ${array_set_in_main_A[@]}"
echo "Can I see array_set_in_level_1_A: ${array_set_in_level_1_A[@]}"


set_in_level_2_A="965"
set_in_level_2_B="432"
set_in_level_2_C="131"

array_set_in_level_2_A=( "tag" "enemy")
array_set_in_level_2_B=( "hash" "bacon")
array_set_in_level_2_C=( "tr" "egg")

echo "set_in_level_2_A: $set_in_level_2_A"
echo "set_in_level_2_B: $set_in_level_2_B"
echo "set_in_level_2_C: $set_in_level_2_C"

echo "array_set_in_level_2_A: ${array_set_in_level_2_A[@]}"
echo "array_set_in_level_2_B: ${array_set_in_level_2_B[@]}"
echo "array_set_in_level_2_C: ${array_set_in_level_2_C[@]}"

#	Modify values in main script and in level1()
set_in_level_1_C="999"
array_set_in_level_1_C=( "999" "999")

set_in_main_C="999"
array_set_in_main_C=( "999" "999")


}
############################## Main script
echo "##################################"

set_in_main_A="543"
set_in_main_B="901"
set_in_main_C="444"

array_set_in_main_A=( "sd" "rg")
array_set_in_main_B=( "5y" "jy")
array_set_in_main_C=( "lp" "####")

echo "In Main, before calling level1()"
echo "set_in_main_A: $set_in_main_A"
echo "set_in_main_B: $set_in_main_B"
echo "set_in_main_C: $set_in_main_C"

echo "array_set_in_main_A: ${array_set_in_main_A[@]}"
echo "array_set_in_main_B: ${array_set_in_main_B[@]}"
echo "array_set_in_main_C: ${array_set_in_main_C[@]}"

echo "Calling level1()."
level1

echo "##############################"
echo "In Main, after calling level1()"
echo "Can I see set_in_level_1_A? $set_in_level_1_A"
echo "Can I see set_in_level_2_A? $set_in_level_2_A"
echo "Have the functions changed the values that were originally set in main()?"
echo "set_in_main_A: $set_in_main_A"
echo "set_in_main_B: $set_in_main_B"
echo "set_in_main_C: $set_in_main_C"
echo "array_set_in_main_A: ${array_set_in_main_A[@]}"
echo "array_set_in_main_B: ${array_set_in_main_B[@]}"
echo "array_set_in_main_C: ${array_set_in_main_C[@]}"