Add a folder containing multiple jar files in the classpath of a java program
java -Djava.ext.dirs=<jarDirectory>
- This works, but watch out, pass the -Djava.ext.dirs= BEFORE -jar –
- java.ext.dirs will work very different from a normal jar in classpath. It has higher priority and permission which will able to somehow override classes in bootstamp(rt.jar)
Some useful tools for memory profiling:
Free/Open-source Tools: (In order of preference)
- MAT (Memory Analyzer Tool): http://www.eclipse.org/mat/ (eclipse update site - http://download.eclipse.org/mat/1.0/update-site/)
- VisualVM: https://visualvm.dev.java.net/ (Comes as part of later versions of JDK1.6)
- JMAP: https://olex.openlogic.com/packages/jmap
Commercial Tools: (In order of preference) [Free tools should be good enough to find out major memory leaks]
- JProbe
- JProfiler
- YourKit
Excellent article on memory profiling:
http://olex.openlogic.com/wazi/2009/how-to-fix-memory-leaks-in-java/
df: (disk free)
Df –k <directory name>
e.g. df –k . or df –k /
du: (disk usage)
The disk usage (du) command shows the size of each file or directory in the current directory:
y> du -sk * | sort -n
The "s" option returns a summary of a directory's contents (rather than a full listing), and the "k" option shows the output in 1 KB increments (rather than the default 512 byte increments). The sort command lists them in ascending size order, with the largest directory last.
This will show which directory is using your space, "home," "pub," or "mail." (Ignore the "backup" directory; that is for the nightly backup snapshot and does not impact your disk usage.)
y> du -sk * | sort -n
6234 mail
6018 pub
182819 home
95045 backup
In this example, the home directory is where most of the space is being used: almost 183 MB.
Command to Find/Delete n-days old files… Especially useful for cleaning up logs. (if you are not using rolling logs for some reason)
Find n-days old files:
>> find . -type f -mtime +5
Delete n-days old files:
>> find . -type f -mtime +5 | xargs rm
mysql>
Run this command:
GRANT ALL PRIVILEGES ON *.* TO USERNAME@IP IDENTIFIED BY "PASSWORD";
- USERNAME is the username that you would like to create.
- IP is the public IP address of your remote connection.
- PASSWORD is the password you would like to use for this username.
You now must flush MySQL's privileges. Run this command:
FLUSH PRIVILEGES;
Run this command to exit MySQL:
exit;
