Category Archives: HOWTO

parse expect_output in a variable : TCL Data Structure

Sometimes we have to automate our steps through expect, run some commands in remote machine and capture the output of a command in a variable and use that variable in some other task. So here is an example, how we … Continue reading

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python : trace line number with exception

In python we raise exception to catch if anything goes wrong, but sometime with try block we have multiple lines of code and we are not able to track which line exactly throwing the exception. There is way to catch … Continue reading

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ORA-12519: TNS:no appropriate service handler found

The number of database processes that can run in Oracle DB is set to 150 as default which can be viewed from v$resource_limit. select * from v$resource_limit where resource_name = ‘processes’; RESOURCE_NAME CURRENT_UTILIZATION MAX_UTILIZATION INITIAL_ALLOCATION LIMIT_VALUE ————- ——————- ————— —————— … Continue reading

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Accessing Host from Docker Container

Sometime we need to access the services that are running in the host machine to be accessible from the docker container.  e.g. In on of my project, we needed to connect to the oracle db (port 1521) from inside the … Continue reading

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My MongoDB cheatsheet

Few years ago, I was working on one mongoDB project.Its a NoSQL database , easy to learn and its pure JSON based. I learned it myself and had created a cheatsheet for it, so I can easily recall it anytime … Continue reading

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chef attribute : avoiding “undefined method `[]’ for nil:NilClass” error

In chef, when a nested attribute that might not exist/or not crated yet, you can use rescue as a modifier to an if statement. For example, assuming that only some of your nodes have node[‘install_wls’][‘isManaged’]defined: if node[‘install_wls’][‘isManaged’] do the stuff … Continue reading

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chef knife tricks: Add a node in an environment

  Sometime during automation of a large deployment process, we have to bootstrap a node , create environment and add the node in that particular environment on the fly.   Bootstraping : 2. Create environment dynamically from inside the programme:(python … Continue reading

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