Author Archives: ronaldpringadi

List open or listening ports

MacOS 1lsof -nP -i4TCP RedHat/Centos7 1netstat -tulpn

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MongoDB Notes

When using MongoDB to store files, we have 2 collections: 1. The place where MongoDB store the file metadata: store.files 2. Ans place where MongoDB store the file content: store.chunks Depending on the size of the file, one entry in … Continue reading

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CentOS 6 repo Settings

To fix repo settings in CentOS 6 1. make sure there is no proxy or funny settings in vi /etc/yum.conf 2. There are a couple of files within /etc/yum.repos.d/. Make sure the url are correct (accessible) and enabled=1 ll /etc/yum.repos.d/ … Continue reading

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Show Linux Partition Tree Mountpoint and If SSD

1lsblk -o TYPE,NAME,KNAME,UUID,MOUNTPOINT,SIZE,ROTA

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Setting log4j log level programmatically

12345678910111213141516private static void setupLog4j() {         System.out.println("setupLog4j");         BasicConfigurator.resetConfiguration();         // Start clean.         Logger.getRootLogger().removeAllAppenders();         // Create appender         ConsoleAppender console … Continue reading

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Print java stack trace from anywhere

Need to know which code call a specific location? Dump the stack trace: 1LOG.trace(ExceptionUtils.getStackTrace(new Throwable()));

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Knowing you exception class name

To know what is your exception class name, in case you want to have a more specific catch. 1234        } catch (Exception e){             LOG.error("SQL error when processing " + requestId+". Exception … Continue reading

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SELinux directory permission

To check SELinux directory permission you need to -z for example 1ls -Z /var/www/html If something is incorrect you can re-adjust some of the directory permission: 1chcon -R -t httpd_sys_content_t /var/www/html

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RedHat / Centos Firewall

To add an exception to firewall In RedHat/CentOS 6 12345iptables –line -vnL iptables -A INPUT -p tcp –dport 80 -m state –state NEW,ESTABLISHED -j ACCEPT iptables -A INPUT -p tcp -s 192.168.0.0/16 -j ACCEPT iptables -D INPUT -p tcp -s … Continue reading

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Bash string comparison

1234567891011121314151617181920212223242526272829303132333435363738394041424344454647484950515253545556575859606162636465#!/bin/bash function test(){ echo "" echo "TEST $1" echo "VAR_1: $VAR_1 VAR_2: $VAR_2 " if [ "$VAR_1" = "false" ]; then echo " VAR_1 is false"; fi if [ "$VAR_2" = "false" ]; then echo " VAR_2 is false"; fi … Continue reading

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