Problem Converting Morse Code to Text using sed - bash

Question

I am kinda new to bash scripting so bear with me.
I have a task to convert text to morse code and vice versa from a given .txt file.
I successfully did the first part but when i try to run the second script to translate from morse to text i get this error:
sed: can't read s/.-/A/g: No such file or directory
S
My original code:
#!/bin/bash
sed 's/.-/A/g' -e 's/-.../B/g' -e 's/-.-./C/g' -e 's/-../D/g' -e 's/./E/g' -e 's/..-./F/g' -e 's/-
-./G/g' -e 's/..../H/g' -e 's/../I/g' -e 's/.---/J/g' -e 's/-.-/K/g' -e 's/.-../L/g' -e 's/--/M/g' -e
's/-./N/g' -e 's/---/O/g' -e 's/.--./P/g' -e 's/--.-/Q/g' -e 's/.-./R/g' -e 's/.../S/g' -e 's/-/T/g'
-e 's/..-/U/g' -e 's/...-/V/g' -e 's/.--/W/g' -e 's/-..-/X/g' -e 's/-.--/Y/g' -e 's/--../Z/g' -e
's/...../1/g' -e 's/....-/2/g' -e 's/...--/3/g' -e 's/....-/4/g' -e 's/...../5/g' -e 's/-..../6/g' -e
's/--.../7/g' -e 's/---../8/g' -e 's/----./9/g' -e 's/-----/0/g' Morse_Text.txt
The Morse_Text.txt file:
-- --- .-. … . -.- --- -.-. .

Answer 1

You have to escape (prepend a \) the . characters, as they have a special meaning in regular expressions.
Like this sed 's/\.-/A/g
Have a look at https://en.wikipedia.org/wiki/Regular_expression
Also you are missing the first -e after your sed command:
░ tamasgal#greybox.local:~
░ 16:37:45 > echo '... --- ...'| sed -e 's/\.\.\./S/g' -e 's/---/O/g'
S O S
Btw. you will hit more issues due to the fact sed works, it will replace parts of other morse codes during the stages.
You should consider including a leading space or new line after each group of morse command.
Here is an example in stages (decoding SOS9):
░ tamasgal#greybox.local:~
░ 16:43:47 > echo '... --- ... ----.'| sed -e 's/\.\.\./S/g'
S --- S ----.
░ tamasgal#greybox.local:~
░ 16:43:56 > echo '... --- ... ----.'| sed -e 's/\.\.\./S/g' -e 's/---/O/g'
S O S O-.
░ tamasgal#greybox.local:~
░ 16:44:00 > echo '... --- ... ----.'| sed -e 's/\.\.\./S/g' -e 's/---/O/g' -e 's/----\./9/g'
S O S O-.
One solution is to include a space or end of line character ($) to each group, like this:
░ tamasgal#greybox.local:~
░ 16:44:02 > echo '... --- ... ----. '| sed -e 's/\.\.\.[ $]/S/g' -e 's/---[ $]/O/g' -e 's/----\.[ $]/9/g'
SOS9
Btw. this is by far an ugly solution, but I'll not do your homework ;)

Answer 2

You have to make sure that the largest matches are replaced first.
It is convenient to store the commands in morse.sed like this:
s/-----/0/g
s/\.\.\.\.\./5/g
s/\.\.\.\.\./1/g
s/\.\.\.\.-/4/g
s/\.\.\.\.-/2/g
s/\.\.\.--/3/g
s/-\.\.\.\./6/g
s/--\.\.\./7/g
s/---\.\./8/g
s/----\./9/g
s/\.\.\.\./H/g
s/\.\.\.-/V/g
s/\.\.-\./F/g
s/\.-\.\./L/g
s/\.--\./P/g
s/\.---/J/g
s/-\.\.\./B/g
s/-\.\.-/X/g
s/-\.-\./C/g
s/-\.--/Y/g
s/--\.\./Z/g
s/--\.-/Q/g
s/\.\.\./S/g
s/\.\.-/U/g
s/\.-\./R/g
s/\.--/W/g
s/-\.\./D/g
s/-\.-/K/g
s/--\./G/g
s/---/O/g
s/\.\./I/g
s/\.-/A/g
s/-\./N/g
s/--/M/g
s/\./E/g
s/-/T/g
Now you can use
sed -Ef morse.sed Morse_Text.txt