Shell script to check the null or empty string
To check whether a string is null
To check whether a string is empty is little trick, many websites suggest a different way. Easy way to do is
#remove all the blank spaces in the string and check for null.
trimString=`echo $title | sed 's/ //g'`
if [ "$trimString" = "" ]
then
echo "string is null"
fi
or
if [[ -z "$trimString" ]]
then
echo "string is null"
fi
Remove all the white spaces is necessary because an empty string may have 1 or 2 or n contiguous white spaces and to handle the string comparision for all these cases you need to remove the blank spaces and add check for null.
Please add Suggestions to improve the scripts if any :)
To check whether a string is null
if [[ -z "$String" ]]then echo "string is null"fi
To check whether a string is empty is little trick, many websites suggest a different way. Easy way to do is
#remove all the blank spaces in the string and check for null.
trimString=`echo $title | sed 's/ //g'`
if [ "$trimString" = "" ]
then
echo "string is null"
fi
or
if [[ -z "$trimString" ]]
then
echo "string is null"
fi
Remove all the white spaces is necessary because an empty string may have 1 or 2 or n contiguous white spaces and to handle the string comparision for all these cases you need to remove the blank spaces and add check for null.
Please add Suggestions to improve the scripts if any :)