padding.sh

#!/bin/sh
# padding output using printf
# reference: https://stackoverflow.com/questions/4409399/padding-characters-in-printf#4410103

pad=$(printf '%0.1s' "-"{1..60})
padlength=40
string2='bbbbbbb'
for string1 in a aa aaaa aaaaaaaa; do
     printf '%s' "$string1"
     printf '%*.*s' 0 $((padlength - ${#string1} - ${#string2} )) "$pad"
     printf '%s\n' "$string2"
     string2=${string2:1}
done

# ========================================
# =                output                =
# ========================================
# 
# a--------------------------------bbbbbbb
# aa--------------------------------bbbbbb
# aaaa-------------------------------bbbbb
# aaaaaaaa----------------------------bbbb