[root@CentOS7 bin]# ./startup.sh -p 3333 which: no javac in (/usr/local/sbin:/usr/local/bin:/usr/sbi

[root@CentOS7 bin]# ./startup.sh -p 3333
which: no javac in (/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/root/bin)
readlink: 缺少操作数
Try 'readlink --help' for more information.
dirname: 缺少操作数
Try 'dirname --help' for more information.
ERROR: Please set the JAVA_HOME variable in your environment, We need java(x64)! jdk8 or later is better! !!

[root@CentOS7 bin]# which java
/usr/bin/java
[root@CentOS7 bin]# ls -lrt /usr/bin/java
lrwxrwxrwx. 1 root root 22 3月   5 16:10 /usr/bin/java -> /etc/alternatives/java
[root@CentOS7 bin]# ls -lrt /etc/alternatives/java
lrwxrwxrwx. 1 root root 71 3月   5 16:10 /etc/alternatives/java -> /usr/lib/jvm/java-1.8.0-openjdk-1.8.0.262.b10-1.el7.x86_64/jre/bin/java

[root@CentOS7 bin]# java -version
openjdk version "1.8.0_262"
OpenJDK Runtime Environment (build 1.8.0_262-b10)
OpenJDK 64-Bit Server VM (build 25.262-b10, mixed mode)

export JAVA_HOME=/usr/lib/jvm/java-1.8.0-openjdk-1.8.0.262.b10-1.el7.x86_64/
export JRE_HOME=$JAVA_HOME/jre
export CLASSPATH=$JAVA_HOME/lib:$JRE_HOME/lib:$CLASSPATH
export PATH=$JAVA_HOME/bin:$JRE_HOME/bin:$PATH