Print process call stack. Pure BASH function.

print_process_call_stack.sh

#!/bin/bash

# based on https://stackoverflow.com/a/1438241/2566213
# pure BASH solution

print_process_call_stack() {
    local -a trace=()
    local -- cmdline
    local -i pid=$$ ppid

    while (( pid )) ; do
        cmdline="$(
            while read -r -d $'\0' f ; do
                printf "%s " "${f}"
            done < "/proc/${pid}/cmdline"
        )"
        trace+=( "$(printf "[%7d]: %s" "${pid}" "${cmdline}" )" )
        ppid="$(
            while read -r key val1 ; do
                if [[ "${key}" == "PPid:" ]] ; then
                    echo "${val1}"
                    break
                fi
            done < "/proc/${pid}/status"
        )"
        pid=${ppid}
    done

    echo "Backtrace of '$0':"
    for (( i=${#trace[@]} - 1 ; i >= 0  ; i-- )) ; do
        printf "  %s\n" "${trace[$i]}"
    done
}