Q:

Bash script to get ASCII values for alphabet

How do I get the ASCII value of the alphabet?
For example, 97 for a?

A:

Define these two functions (usually available in other languages):
chr() {
  [ "$1" -lt 256 ] || return 1
  printf "\\$(printf '%03o' "$1")"
}

ord() {
  LC_CTYPE=C printf '%d' "'$1"
}

Usage:
chr 65
A

ord A
65

A:

You can see the entire set with:
$ man ascii

You'll get tables in octal, hex, and decimal.

A:

This works well,
echo "A" | tr -d "\n" | od -An -t uC

echo "A"                              ### Emit a character.
         | tr -d "\n"                 ### Remove the "newline" character.
                      | od -An -t uC  ### Use od (octal dump) to print:
                                      ### -An  means Address none
                                      ### -t  select a type
                                      ###  u  type is unsigned decimal.
                                      ###  C  of size (one) char.

exactly equivalent to:
echo -n "A" | od -An -tuC        ### Not all shells honor the '-n'.

