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Unix Detective: Port of Call

Recently I had to administer an Unix server with no runbook. The immediate task was to find the application listening on port 8888, make some modifications, and restart.

1.) Find process listening on port 8888

netstat -plan | grep 8888

The output is

tcp     0   0 :::8888   :::*    LISTEN      2700/java 

This shows me that a java program at Process ID (PID) 2700 is listening on port 8888

2.) Find process info of PID 2700

ps -fp 2700 | more

The output is

oracle  2700   1  0 18:55 ?     0:00:02 
/usr/java/latest/bin/java -Xmx1024m -Xms256m -Dapex.port=8888
-jar/home/oracle/listener/apex.war 2>&1 >/tmp/apexListener.log

This shows me the full command line for PID 2700. Luckily the command line has all the necessary information like program type (Oracle Apex), log location, war file location, temporary directory, etc.

Sometimes we do not get so lucky and the command line is more cryptic. If that  is the case, execute command

lsof -p 2700

That command shows a list of open files used by process 2700. That will usually lead to log location and other important files.


java    2700 oracle    2w   REG        3,1     1700 1796967 /tmp/apex_listener.log
java    2700 oracle    3r   REG       3,65  9828505  134585 /home/oracle/listener/apex.war
java    2700 oracle    4r   REG        3,1 51796975  361047 /usr/java/jdk1.6.0_20/jre/lib/rt.jar
java    2700 oracle    5r   REG       3,65  1869025  132940 /home/oracle/tmp/apex/apex/____embedded/start.jar
java    2700 oracle    6r   REG       3,65  1539291  132946 /home/oracle/tmp/apex/apex/WEB-INF/lib/poi-3.6-20091214.jar

3.) Find how to stop and start the application
The ps -fp command in step 2 shows me that the parent process PID is 1. (It is the number after 2700). 

ps -fp 1 | more

gives the output

root    1     0  0 18:54 ?    00:00:00 init [5]

The command init is the startup script process that executes when Unix first boots up.  The startup scripts are in directory /etc/init.d

cd /etc/init.d
find . -name "*" | xargs grep apex

The output is

./oracle:   su - oracle -c "/home/oracle/ start"
./oracle:   su - oracle -c "/home/oracle/ stop"

Reading the file ./oracle with the command

more ./oracle

shows me how to stop and start Oracle Apex.

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