Work -z on unix

Question

if [ -z "${ABC}" ] then LOGDIR=`${JAVA_HOME}/bin/java -cp ${a}/aim.jar my.app.util.GetLogDir "${rsp}"` 

Can someone help me. What is it, if that's for sure. Checks if abc and the calling GetLogDir main exist with some arguments?

Answer 1

  -z string True if the length of string is zero. 

Check if ABC empty. If so, the command will be executed and the result will be in LOGDIR .

Answer 2

From a human test:

  -z string True if the length of string string is zero.