./standalone.sh: 1: eval: /opt/java/jdk1.7.0_21/bin/java: not found
Someone assist on how to fix the above erro kindly. Am trying to run a ./standalone.sh command in the terminal but am getting the above error.

On my kubuntu system, I get this

$ ls -l /usr/bin/java
lrwxrwxrwx 1 root root 22 mars   5  2014 /usr/bin/java -> /etc/alternatives/java
$ ls -l /etc/alternatives/java
lrwxrwxrwx 1 root root 46 mars   5  2014 /etc/alternatives/java -> /usr/lib/jvm/java-7-openjdk-amd64/jre/bin/java

Your java executable may have a different location. You can also try

locate bin/java

Your /usr/bin/java is a link to /opt/java/jdk1.7.0_21/bin/java, but it doesn't exist, or is somewhere else.

Just need to add the path to your enviroment. Using "echo $PATH"
displays you current path. you need to add the path of the script to you env using

PATH=$PATH\:/dir/path ; export PATH

and do upgrade to the latest release from Oracle. 1.8.0_60 as of writing.
1.7.0_79 is the last 1.7 release, mostly security fixes and some minor stuff.