caller [EXPR]
Returns the context of the current subroutine call.
Without EXPR, returns "$line $filename". With EXPR, returns "$line $subroutine $filename"; this extra information can be used to provide a stack trace.
The value of EXPR indicates how many call frames to go back before the current one; the top frame is frame 0.
Call Stack Entry Format
Each entry in the session's call_stack should be a map with:
:line_number- The line number where the function was called from:function_name- The name of the function being called:source_file- The source file containing the call
Exit Status
Returns 0 if the specified frame exists, 1 otherwise (including when not in a function).
Reference: https://cgit.git.savannah.gnu.org/cgit/bash.git/plain/builtins/caller.def?h=bash-5.3