mjhjmtu

I am trying to compare the string stored in a variable with three different strings and if none of them match then throw an error. I've tried to do this in a single if statement using the logical operator OR. But every time I am getting error even though the value stored in the variable is same as one of the possible value. Please find the snippets I tried.

if [[ "$TYPE" != "LOCAL" || "$TYPE" != "REMOTE" || "$TYPE" != "BOTH" ]]; then
 echo -e "ntINCORRECT OR NULL ARGUMENTS PASSED. PLEASE VERIFY AND CORRECT THE USAGE MENTIONED AS BELOW: n"
 Usage
 exit 1
fi


if [[ "$TYPE" != "LOCAL" ]] || [["$TYPE" != "REMOTE" ]] || [["$TYPE" != "BOTH" ]]; then
 echo -e "ntINCORRECT OR NULL ARGUMENTS PASSED. PLEASE VERIFY AND CORRECT THE USAGE MENTIONED AS BELOW: n"
 Usage
 exit 1
fi

You've got your logic backward. Any string is guaranteed to be either different from LOCAL or different from REMOTE because a string cannot be LOCAL and REMOTE at the same time.

Here, the right tool for the task is a case statement (which is standard sh syntax contrary to those [[...]] ksh operators):

case $TYPE in
 (REMOTE|LOCAL|BOTH) ;; # OK
 (*) printf >&2 'Error...n'; exit 1;;
esac

If you wanted to use [[, in ksh or bash or zsh in ksh emulation you could do:

if [[ $TYPE != @(REMOTE|LOCAL|BOTH) ]]; then
 printf >&2 'Error...n'
 exit 1
fi

Or [[ $TYPE != REMOTE && $TYPE != LOCAL && $TYPE != BOTH ]] or [[ ! ($TYPE = REMOTE || $TYPE = LOCAL || $TYPE = BOTH) ]], etc.

Or using the standard [ command: [ "$TYPE" != REMOTE ] && [ "$TYPE" != LOCAL ] && [ "$TYPE" != BOTH ].

With ksh93, bash or zsh, another option is to use an associative array:

typeset -A allowed_TYPE
allowed_TYPE=([REMOTE]=1 [LOCAL]=1 [BOTH]=1)
if ((!allowed_TYPE[$TYPE])); then
 printf >&2 'Error...n'
 exit 1
fi

With zsh, you can also use a plain array:

 allowed_TYPE=(REMOTE LOCAL BOTH)
 if ((! $allowed_TYPE[(Ie)$TYPE]))...

[updated]

maybe not the cleanest method, but it works.

declare an array variable and loop through it using awk to count the number of types that match in the declared array :

declare -a a=("LOCAL" "REMOTE" "BOTH")
types=$(echo $a[@] | wc -w)
val=$(echo $a[@] | awk -v TYPE="$TYPE" 'split($0,a," ");for (key in a) if (a[key] != TYPE) print "#"' | wc -l)
if [ $val -eq $types ]; then # if 0 matches 
 echo "error"; exit 1; 
fi

thanks to Stéphane Chazelas for pointing out the flaw in my previous answer.