To avoid callback hell , a very useful tool for structuring calls in a sequence and make sure the steps pass the data to the next step. nJoy 😉
Async waterfall example nodejs
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Category: Uncategorized
Node.js Start script or run command and handoff to OS (no waiting)
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Sometimes you want to run something in the OS from your node code but you do not want to follow it or have a callback posted on your stack. The default for child_process spawning is to hold on to a handle and park a callback on the stack. however there is an option which is…
Identify OS on remote host
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For nmap to even make a guess, nmap needs to find at least 1 open and 1 closed port on a remote host. Using the previous scan results, let us find out more about the host 192.168.0.115: # nmap -O -sV 192.168.0.115 Output: Starting Nmap 7.80 ( https://nmap.org ) at 2020-10-02 12:21 CEST Nmap scan…
How to quit ESXi SSH and leave background tasks running
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In Linux when a console session is closed most background jobs (^Z and bg %n) will stop running when the parent ( the ssh session ) is closed because the parent sends a SIGHUP to all its children when closing (properly). Some programs can catch and ignore the SIGHUP or not handle it at all…
Upgrading Certbot Lets Encrypt on Ubuntu
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😉 nJoy
Convert Large numbers to binary in Excel
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=DEC2BIN(MOD(QUOTIENT($A$1,16^7),16),4)&” “&DEC2BIN(MOD(QUOTIENT($A$1,16^6),16),4)&” “&DEC2BIN(MOD(QUOTIENT($A$1,16^5),16),4)&” “&DEC2BIN(MOD(QUOTIENT($A$1,16^4),16),4)&” “&DEC2BIN(MOD(QUOTIENT($A$1,16^3),16),4)&” “&DEC2BIN(MOD(QUOTIENT($A$1,16^2),16),4)&” “&DEC2BIN(MOD(QUOTIENT($A$1,16^1),16),4)&” “&DEC2BIN(MOD(QUOTIENT($A$1,16^0),16),4) The above code will convert large numbers up to 32 bit. nJoy 😉
SYSTEMD – controls
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Starting with Ubuntu 15.04, Upstart will be deprecated in favor of Systemd. With Systemd to manage the services we can do the following: systemctl start SERVICE – Use it to start a service. Does not persist after reboot systemctl stop SERVICE – Use it to stop a service. Does not persist after reboot systemctl restart…
Fixing keyboard in ubuntu
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sudo dpkg-reconfigure keyboard-configuration nJoy 😉
Using ngrok with React based websites
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The problem : When we have a react.js based site (hosted on port 8000) and ngrok it for development purposes we get Invalid Host Header The fix is to override the header on reflection: ngrok http 8000 -host-header=”localhost:8000″ That’s it 😉 nJoy
Clear Linux Cache
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1. Clear PageCache only. # sync; echo 1 > /proc/sys/vm/drop_caches 2. Clear dentries and inodes. # sync; echo 2 > /proc/sys/vm/drop_caches 3. Clear PageCache, dentries and inodes. # sync; echo 3 > /proc/sys/vm/drop_caches nJoy 😉