Systems

Bash Specific

Restricting CPU utilization of a process

http://blog.scoutapp.com/articles/2014/11/04/restricting-process-cpu-usage-using-nice-cpulimit-and-cgroups

cpulimit -l 50 -p 1234

How to check if a directory exists

https://stackoverflow.com/questions/59838/check-if-a-directory-exists-in-a-shell-script

Others

• Using perf top generates lots of interrupts on the system. Up from 5K/sec to 135K/sec. So, don't use it when profiling.

• reset hung ssh terminal : http://askubuntu.com/questions/124699/why-does-gnome-terminal-freeze-when-an-ssh-session-gets-disconnected - call Enter + ~ + .

• certificate extraction

openssl pkcs12 -clcerts -nokeys -in "YourPKCSFile" -out certificate.crt -password pass:PASSWORD -passin pass:PASSWORD

openssl pkcs12 -cacerts -nokeys -in "YourPKCSFile" -out ca-cert.ca -password pass:PASSWORD -passin pass:PASSWORD

openssl pkcs12 -nocerts -in "YourPKCSFile" -out private.key -password pass:PASSWORD -passin pass:PASSWORD -passout pass:TemporaryPassword

• setting up ssh key names https://askubuntu.com/questions/30788/does-ssh-key-need-to-be-named-id-rsa

sample config file

$cat .ssh/config
Host flex*
StrictHostKeyChecking no 
IdentityFile ~/.ssh/demo

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See java properties:

java -XshowSettings:properties