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rrdcached is a daemon that receives updates to existing RRD files, accumulates them and, if enough have been received or a defined time has passed, writes the updates to the RRD file. A flush command may be used to force writing of values to disk, so that graphing facilities and similar can work with up-to-date data. rrdcached uses the line protocol to communicate with client. When we start rrdcached , it will listen on port 42217 and create a socket file.  We can telnet to port 42217  or use ncat to create a connection to socket file. telnet localhost 42217     or nc -U /var/run/rrdcached/rrdcached.sock AfterRead More →

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### A Detailed Page About PHP Threads: Understanding Multithreading in PHP PHP is one of the most widely used server-side programming languages, primarily known for its ability to generate dynamic web pages and handle requests on web servers. While PHP is designed to be fast and efficient for web development, it traditionally operates on a single-threaded, synchronous model, meaning each request is handled one at a time. This approach is simple, but it can sometimes lead to inefficiencies, particularly when tasks are time-consuming or when there is a need to handle multiple operations simultaneously. In environments where performance is critical or when executing tasks likeRead More →

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You might receive the error Column count of mysql.user is wrong. Expected 42, found 44. The table is probably corrupted , this is probably because you import the whole database from mysql 5.6 to 5.7 . The table structure has changed , so you need to update it. You can use the command mysql_upgrade to do this work for you. After you import the data , run this file mysql_upgrade -uroot -p -h127.0.0.1 -P3306   this command will go all over your databases table and upgrade the database structure . mysql.tables_priv OK mysql.time_zone OK mysql.time_zone_leap_second OK mysql.time_zone_name OK mysql.time_zone_transition OK mysql.time_zone_transition_type OK mysql.user OK UpgradingRead More →

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When we add new data: # vi /etc/apt/sources.list … deb http://deb.debian.org/debian stretch main contrib non-free deb-src http://deb.debian.org/debian stretch main contrib non-free we got some errors below: # apt-get update Hit:1 http://archive.ubuntu.com/ubuntu bionic InRelease Get:2 http://archive.ubuntu.com/ubuntu bionic-security InRelease [83.2 kB] Get:3 http://archive.ubuntu.com/ubuntu bionic-updates InRelease [88.7 kB] Fetched 172 kB in 2s (73.3 kB/s) Reading package lists… Done root@netsgn:~/soft# nano /etc/apt/sources.list root@netsgn:~/soft# apt-get update Hit:1 http://archive.ubuntu.com/ubuntu bionic InRelease Get:2 http://archive.ubuntu.com/ubuntu bionic-security InRelease [83.2 kB] Get:3 http://archive.ubuntu.com/ubuntu bionic-updates InRelease [88.7 kB] Get:4 https://packagecloud.io/grafana/stable/debian stretch InRelease [23.2 kB] Err:4 https://packagecloud.io/grafana/stable/debian stretch InRelease The following signatures couldn’t be verified because the public key is not available: NO_PUBKEY 37BBEE3F7AD95B3F Fix: #Read More →

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I had a samsung J7, it’s in the drawer for many months. today i tried to charge it, there was no sign it’s charging. i changed many cables , i thought the battery is dead. Luckily i have its original charger adapter + cable , i connected it to the phone , the phone starts up . i don’t know if there is any difference between the original charger and other compatible charger. Hope it help you in some cases.Read More →

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rrdtool dump filename.rrd rrdtool info filename.rrd   rrdtool graph /dev/null -s 3600 DEF:ierr=filename.rrd:ds1:AVERAGE VDEF:ioct_a=ierr,AVERAGE PRINT:ierr:%lf this command will get the avg value of ds1 (ds1 is the dataset – you can see it in rrdtool info )  , assign it to variable ierr  and print out #3600 => one hourRead More →

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Create a service: sudo vi /etc/systemd/system/rc-local.service Add your code there: [Unit] Description=/etc/rc.local Compatibility ConditionPathExists=/etc/rc.local [Service] Type=forking ExecStart=/etc/rc.local start TimeoutSec=0 StandardOutput=tty RemainAfterExit=yes SysVStartPriority=99 [Install] WantedBy=multi-user.target Create and make sure /etc/rc.local is executable and add this code inside it: sudo chmod +x /etc/rc.local #!/bin/sh -e # # rc.local # # This script is executed at the end of each multiuser runlevel. # Make sure that the script will “exit 0” on success or any other # value on error. # # In order to enable or disable this script just change the execution # bits. # # By default this script does nothing. exit 0 Enable the service: sudoRead More →