CODEWITHSUNDEEP
regexshell
Cosmic
Cosmic

Reputation: 1

What is the Regular expression for multiple word combinations

Can some one help me to find a regular expression for the pattern below,

I am trying to use regular expression to match a patter in shell script.

The pattern could be a combination of 'ab' 'xy' 'ij' 'pqr', in any order and seperated by a comma ',' or only 'all'

Ex.

1) "ab,xy,ij,pqr" - valid

2) "ij,pqr" - valid

3) "all" - valid

4) "ij,ab," - invalid because it ends with a comma

5) "all,xy" - invalid because 'all' cannot be combined with xy ij pqr or ab

6) ",xy" - invalid because it starts with comma

7) "xy" - valid

Thank you.

@konsolebox @491243 @ajp15243 @Jerry Looks like I am doing something wrong, it works only for the RE regex4="(ab|xy|ij|pqr)(,(ab|xy|ij|pqr))*" so far and that too only if the string is like "ab,xy" just "ab" doesn't work. Here is what I have attempted so far:

#!/usr/bin/ksh

echo
echo echo $1
echo

regex2="^(all|(ab|xy|ij|pqr)(,(ab|xy|ij|pqr))*)$"
regex3="^(all|(ab|xy|ij|pqr)(,(ab|xy|ij|pqr))*)$"
regex4="(ab|xy|ij|pqr)(,(ab|xy|ij|pqr))*"

if [[ $1 == $regex2 ]]
then
  echo "You got it again 22222222 !"
fi

if [[ $1 == $regex3 ]]
then
  echo "You got it again 33333333 !"
fi

if [[ $1 == $regex4 ]]
then
  echo "You got it again 44444444 !"
fi

Output:

$
$ test.ksh ab,xy

echo ab,xy

You got it again 44444444 !
$
$
$
$ test.ksh ab

echo ab

$

1:30 PST

Ok, had some improvement:

"((ab|xy|ij|pqr)|(ab|xy|ij|pqr)(,(ab|xy|ij|pqr))*)|all)$"

this one works when the input is "xy", "xy,ab" but it also treating "xy,ab,all" as valid input.

Upvotes: 0

Views: 1481

Answers (3)

Cosmic
Cosmic

Reputation: 1

ok, looks like finially the below RE worked, thank you all for the help.

(all)|(ab|xy|ij|pqr)|(ab|xy|ij|pqr)(,(ab|xy|ij|pqr)*)

Upvotes: 0

konsolebox
konsolebox

Reputation: 75488

Probably this:

^(all|(ab|xy|ij|pqr)(,(ab|xy|ij|pqr))*)$

Upvotes: 1

John Woo
John Woo

Reputation: 263723

I think this will do it.

^(((ab|xy|ij|pqr)(,(ab|xy|ij|pqr))*)|all)$

Upvotes: 1

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