Shell Programming and Scripting

I want to block all special characters except alphanumerics.. and "."(dot ) character

currently am using /[^a-zA-Z.]/

I want to even block only single dot or multiple dots..

ex:
. or .............. should be blocked.

please provide me the reg ex.

---------- Post updated at 05:11 AM ---------- Previous update was at 04:19 AM ----------

am trying =>[^a-zA-Z .{1}] . this is not working

Please provide me the solution asap

can you please elaborate this?
better give an example.

choose the test you want from below:-

example:-

Code:

shopt -s extglob

INPUT="Ad123"

case $INPUT in
   ( +([[:digit:]])  ) echo "$INPUT is all numbers" ;;
   ( +([[:alpha:]])  ) echo "$INPUT is all characters" ;;
   ( +([[:alnum:]])  ) echo "$INPUT is alphanumeric" ;;
   (                *) echo "$INPUT is empty or something unknown" ;;
esac

Code:

o/p
Ad123  is alphanumeric

@anchal

in first name field I want to block multiple dots
ex:

FirstName should not be => . (dot)or .......(multiple dots)

it can be => a.b.c.

am using => split( [^a-zA-Z0-9.] )


But it does not work

Hello,
what do you mean by this "I want to even block only single dot or multiple dots..
". this implies that you dont want dots at all?
the regex that you are trying is absolutely wrong.
In [ ] (character class) {}(counter) doesnt work. except it becomes a literal.
([^a-zA-Z]) implies that these alphabets are not included contrary to the one you have stated above. -> "want to block all special characters except alphanumerics.. "..

are you sure you should allow single dot at the end?
if yes, this should work ( please test first)

Code:

^([a-zA-Z0-9]+\.?)+$

if you dont want dot at the end:

Code:

^([a-zA-Z0-9]+\.?)+[^.]$