CODEWITHSUNDEEP
bash
Marvin Danig
Marvin Danig

Reputation: 3938

How to apply multiple validations to an argument in bash script?

I have a bash script that reads input from the user and validates if the inputted value exists (non-blank) and is an even integer. I'm using the terse test "$1" to test if input exists but combining it with other validation methods does not seem to work. My validation methods are like so:

readValidBookLength() {
  BOOKLENGTH=$1

  while ! [ isValidBookLength $BOOKLENGTH ] && ! [ isBookLengthNumeric $BOOKLENGTH ] && [isBookLengthEvenNumber $BOOKLENGTH]; do
    echo -e 'Book length? (HINT: An even number!): \c'
    read -r BOOKLENGTH
  done    
}

isValidBookLength() {
  test "$1" 
}

isBookLengthNumeric() {
  echo "I GOT HERE!"
  BOOKLENGTH=$1

  echo "${BOOKLENGTH}"
  reg='^[0-9]+$'
  if ! [[ $BOOKLENGTH =~ $reg ]] ; then
    return 1
  else
    return 0
  fi
}

isBookLengthEvenNumber() {
  echo "I GOT HERE 2!"
  BOOKLENGTH=$1
  echo "${BOOKLENGTH}"
  if [ $((BOOKLENGTH%2)) -eq 0 ] ; then
    return 0
  else
    return 1
  fi  
}

Is this pattern of seeking a valid input after multiple validations correct. What am I missing here?

Upvotes: 0

Views: 216

Answers (2)

Barmar
Barmar

Reputation: 782785

You shouldn't put [ before the calls to your validation functions. [ is a short name for the test command. You also need to group all the tests together and negate the whole group:

while ! { isValidBookLength "$BOOKLENGTH" && isBookLengthNumeric $BOOKLENGTH && isBookLengthEvenNumber $BOOKLENGTH; }; do

Upvotes: 2

rob mayoff
rob mayoff

Reputation: 386058

It looks like you want the loop to continue to execute if any of the tests fail. That means you should use ||, not &&, to combine the tests.

Upvotes: 0

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