DISQUS

Anonymous · 5 years ago

Wouldn't the following be better?

if [ -z $var ];then
echo null
fi
Anonymous · 1 year ago

i believe the $var needs to be in quotes, like so:

if [ -z "$var" ];then
echo null
fi

Best Regards,
Kibokina
netuddki · 2 weeks ago

The correct solution is here a year ago. It should be corrected in the article too, so one won't try those for 10 minutes before finding the answer here.
guest · 5 years ago

the following syntax is wrong

if [ $var == "" ] ......

because if the variable $var is empty the test is
if [ == "" ] and gives an error

you are obliged to quote the var :
if [ "$var" == "" ] ...

Sergio
BhupinderSingh · 4 years ago

this can also be used to compare 2 strings

s1 = "as"
s2 = "bs"

if test $s1 == $s2
then
echo s1 and s2 are equal
fi
bhargav · 7 months ago

if [ "$var" = "value" ]
then
echo not the same
fi
asd · 7 months ago

These examples don't work.
Florin · 6 months ago

This is the method i curently to test if a string is empty:

if [ "X${VAR}" = "X" ]; then
echo "Empty string"
fi

Testing for equality follows the same logic but without X.