shell script check if variable is empty code example

Example 1: bash if null or empty

if [ -z "$variable" ];
  then echo "$variable is null";
  else echo "$variable is not null";
fi

Example 2: bash if variable is not empty

VAR=`echo Hello world`
if [[ -n "$VAR" ]] ; then echo "Variable is set" ; fi

Example 3: bash check if variable is empty

if [ -z "$var" ] #return true if $var is unset

Example 4: javascript check if variable is empty

if( value ) {
  //
}

/**
* This will evaluate to true if value is not:
* null
* undefined
* NaN
* empty string ("")
* 0
* false
*/

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