An answer to a reddit post that I gave here: https://www.reddit.com/r/bash/comments/vycqj8/can_someone_answer_this_please/

totable.sh

#!/bin/bash

table_max_width="${2:-80}"

# TO-DO: Add some smarts at this point to minimise issues caused by uneven column widths
# Subtract for our pipechars
# ---------|-----|------|-----|------|-----|------|
#          ^            ^            ^            ^ These particular guys
columns_max_width="$(( table_max_width - 4 ))"

mapfile -t rawlines < "${1}"

# Calculate the width of the left 'A' column.
# ---------|------------|------------|------------|
# ^^^^^^^^^ this bit, excluding the pipe char
# In this example, we use the 'A1' cell as a proxy, and add 1 char of padding
# A fuller solution might look like "pull all lines that start with a char,"
# "then sort them by size, selecting the longest"
# shellcheck disable=SC2086
set -- ${rawlines[0]}
col_A_width="$(( "${#1}" + 1 ))"

# Subtract from our maximum width, then split in three for A2, A3 and A4
columns_max_width=$(( columns_max_width - col_A_width ))

# This figures out this width
# ---------|-----|------|-----|------|-----|------| 
#           ^^^^^^^^^^^^
col_BC_width=$(( columns_max_width / 3 ))
# The rest are the same, so don't recalc them, just copy them
col_DE_width="${col_BC_width}"
col_FG_width="${col_BC_width}"

# Now we split into our subcolumns
# Don't forget to subtract by 1 for a pipechar
# ---------|-----|------|-----|------|-----|------|
#                ^ this guy
col_B_width="$(( (col_BC_width - 1) / 2 ))"
# Everything else should be the same width
col_C_width="${col_B_width}"
col_D_width="${col_B_width}"
col_E_width="${col_B_width}"
col_F_width="${col_B_width}"
col_G_width="${col_B_width}"

# shellcheck disable=SC2183
print_top_border() {
    printf -- '%*s+' "${col_A_width}" | tr ' ' "-"
    printf -- '%*s+' "${col_BC_width}" | tr ' ' "-"
    printf -- '%*s+' "${col_DE_width}" | tr ' ' "-"
    printf -- '%*s+\n' "${col_FG_width}" | tr ' ' "-"
}

# shellcheck disable=SC2183
print_mid_border() {
    printf -- '%*s+' "${col_A_width}" | tr ' ' "-"
    printf -- '%*s+' "${col_B_width}" | tr ' ' "-"
    printf -- '%*s+' "${col_C_width}" | tr ' ' "-"
    printf -- '%*s+' "${col_D_width}" | tr ' ' "-"  
    printf -- '%*s+' "${col_E_width}" | tr ' ' "-"
    printf -- '%*s+' "${col_F_width}" | tr ' ' "-"
    printf -- '%*s+\n' "${col_G_width}" | tr ' ' "-"   
}

print_headers() {
    # shellcheck disable=SC2086
    set -- ${rawlines[0]}
    printf -- "%-${col_A_width}s|%${col_BC_width}s|%${col_DE_width}s|%${col_FG_width}s|\n" "${1}" "${2}" "${3}" "${4}"
}

# shellcheck disable=SC2059
print_mid_line() {
    print_fmt="%-${col_A_width}s|%${col_B_width}s|%${col_C_width}s|%${col_D_width}s|"
    print_fmt="${print_fmt}%${col_E_width}s|%${col_F_width}s|%${col_G_width}s|\n"
    printf -- "${print_fmt}" "${1}" "${2}" "${3}" "${4}" "${5}" "${6}" "${7}"
}

main() {
    print_top_border
    print_headers
    print_mid_border
    while read -r; do
        case "${REPLY}" in
            (Trial*)
                print_mid_line ${REPLY}
            ;;
            (*)
                print_mid_line "" ${REPLY}
            ;;
        esac
        print_mid_border
    done < <(printf -- '%s\n' "${rawlines[@]:1}")
}

main