Bash++ Recursion

#!/bin/bash ############################################################ # Example script to demonstrate recursion without the # use of subshells # # John Robertson <john@rrci.com> # Initial release: Thu Sep 10 11:58:23 EDT 2020 # # Halt on error, no globbing, no unbound variables set -efu # import return stack tools source ../bash++ # "static" array of phrases to be assembled into # a sentence by recurse() declare -a Phrase_arr=(\ [0]='Now is' \ [1]='the time for' \ [2]='all good' \ [3]='men to come' \ [4]='to the aide of' \ [5]='their country'\ ) # Convenient "constant" Phrase_arr_sz=${#Phrase_arr[@]} function recurse () ####################################################### # Example recursive function works without subshells # Arguments: # Recursion level # Returns: # contcatenated phrases # { local lvl=$1 # Continue recursing until out of phrases if (( lvl + 1 < Phrase_arr_sz )); then # Call ourself again with incremented lvl recurse $(( lvl + 1 )) # Pop the result into R1 RTN_pop R1 # Push concatenated result on return stack RTN_push "${Phrase_arr[$lvl]} $R1" else # Push final phrase on return stack RTN_push "${Phrase_arr[$lvl]}" fi } ################################### ### Execution starts here ######### ################################### # NOTE: We'll reserve R1 R2 R3 ... global # variables to fetch return values from # return stack. # Recursively assemble sentence from Phrase_arr recurse 0 # Retrieve sentence from return stack RTN_pop R1 # Print result echo "Result: '$R1'" 

Result: 'Now is the time for all good men to come to the aide of their country'