Shell Programming and Scripting

I got syntax error after replacing ! with ^

./bb.sh: syntax error at line 21: `^' unexpected

Right, sorry for leading you astray, it was a long shot anyway.

If you go back to an individual character in each class, does that help at all?

Code:

case $b in
  *[@!]*) echo has @ in a character class containing exclamation mark also;;
  *[@]*) echo has @ in character class;;
  *@*) echo has @;;
esac

You might want to fill in more cases to see what exactly works and how.

Era, there's no need to apologise. You're just trying to help. I would go astray anyway while trying to find my way to the solution It would probably be worse if I am doing on my own without any help from you. I will update you again after trying your new suggestion. Thanks

Era, I have just remembered the problem of having an individual character in each case. I cannot key in cases as follows because I encountered syntax errors:

*`*) echo "Error";;

*\*) echo "Error";;

*)*) echo "Error";

*(*) echo "Error";

I tried adding "\" in front of each of the character, it failed too. I tried with *\`* but it failed to detect string with 678\989

Yes, you need to backslash-escape (or quote) any characters with special meaning.

Backslash in particular is special when reading too, but if you can just get the others to work, that's a start.

*\`* should match 678`989 not 678\989

Merely quoting closing parenthesis is insufficient, because it has a special meaning in the syntax of the case statement, and quoting won't help the parser, so you need the backslash specifically.

Code:

case $b in
  *\\*) echo backslash;;  # don't necessarily expect this to work
  *\)*) echo close paren;;  # can't just quote this one, either
  *'('*) echo open paren;;
  *'`'*) echo backtick;;
esac

All of those should work IMHO, but $b might not contain a backslash when you expect it to. Consider:

Code:

vnix$ echo 'foo\bar'
foo\bar
vnix$ echo 'foo\bar' | while read b; do
>   set | grep b=
> done
b=foobar
bash205b='3.2.25(1)-release'

See? The backslash is parsed already by read. My bash has an option read -r to disable this but I don't know if that's portable.

Yeah, I agree. I will do what I can first.

If anyone has a better solution, please let me know. I am still desperate for a solution. I regret for agreeing to use Bourne shell to develop this simple application.

POSIX Bourne shell would be quite okay, but it seems the one you have on Sun is rather crippled.

As an alternative workaround, what would happen if you set IFS to all the prohibited characters, and check whether you get more than one token?

Code:

IFS='!"#$%&/'  # etc
read b residue
case $residue in '') ;;  *) echo whoa, illegal chars there buddy >&2;; esac

This is not entirely robust if the only illegal character is the very last one, but maybe that's acceptable.