Introducing a robot fish that is able to swim and recognize tank edges and obstacles. Find out how it can easily create it with common insulating material and a few servo motor controlled by Arduino. Arduino is a single-board microcontroller, intended to make the application of interactive objects or environments more accessible. The hardware consists of an open-source hardware board designed around an 8-bit Atmel AVR microcontroller, or a 32-bit Atmel ARM. Current models feature a USB interface, 6 analog input pins, as well as 14 digital I/O pins which allow the user to attach various extension boards.Using wireless Read more…
Supervisory Control and Data Acquisition (SCADA) is a process control system that enables a site operator to monitor and control processes that are distributed among various remote sites. A properly designed SCADA system saves time and money by eliminating the need for service personnel to visit each site for inspection, data collection/logging or make adjustments. Supervisory control and data acquisition is used to describe a system where both data acquisition and supervisory control are performed. Mobile Supervisory Control and Data Acquisition (referred to as Mobile SCADA) is the use of SCADA with the mobile phone network being used Read more…
Uninterruptible power supplies (UPS) mitigate voltage sags by supplying the load using stored energy. Upon detection of voltage sag, the load is transferred from the mains supply to the UPS. Obviously, the capacity of load that can be supplied is directly proportional to the amount of energy storage available. UPS systems have the advantage that they can mitigate all voltage sags including outages for significant periods of time (depending on the size of the UPS). There are 2 topologies of UPS available; on-line and off-line. Figure 1 shows a schematic of an off-line UPS while Figure 2 shows Read more…
Map-Reduce are a programming model that enables easy development of scalable parallel applications to process vast amounts of data on large clusters of commodity machines. Based on this new framework, we perform extended evaluations of Map Reduce-inspired processing jobs on an IaaS cloud system and compare the results to the popular data processing framework Hadoop. Through a simple interface with two functions, map and reduce, this model facilitates parallel implementation of many real-world tasks such as data processing for search engines and machine learning. In recent years ad hoc parallel data processing has emerged to be one of Read more…
Steps to find the Installation date centos of a Operating system installed Linux CentOS and Red Hat On a CentOS or RedHat based Operation system You can easily find the date and time of the Server is installed. Method 1 : Using, rpm command to find the basesystem and using the basesystem information we can use rpm -qi to find Date and time. Step 1 : First get the basesystem rpm by the below command.
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rpm -qa | grep basesystem |
eg. result below.
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root@earn [~]# rpm -qa|grep basesystem basesystem-8.0-5.1.1.el5.centos |
Step 2 : Copy the whole basesystem version number and input the below command.
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rpm -qi |
eg. base on Read more…
Plesk version 12 throws error Internal error The system cannot find the file specified Recent update from the Plesk version 12 from odin crashed few files & its content. due to this you get the below error. Internal error: The system cannot find the file specified. Message The system cannot find the file specified. File Hierarchical.php Line 105 Type Exception To Resolve the issue : odin also released a new path to address the issue. Reinstall the update using the command from console:
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[crayon-59c9fc104648e397020294 ]"%plesk_bin%\ai.exe" --select-release-current --upgrade-installed-components |
[/crayon] You can also use Plesk Panels GUI to update this micro update.
sar command usage and details examples sar command usage and details examples System Activity Report – SAR used to report on various system loads, including CPU activity, memory/paging, device load, network. Linux distributions provide sar through the sysstat package.
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Usage: sar [ options ] [ <interval> [ <count> ] ] Main options and reports: -b I/O and transfer rate statistics -B Paging statistics -d Block device statistics -I { <int> | SUM | ALL | XALL } Interrupts statistics -m Power management statistics -n { <keyword> [,...] | ALL } Network statistics Keywords are: DEV Network interfaces EDEV Network interfaces (errors) NFS NFS client NFSD NFS server SOCK Sockets (v4) IP IP traffic (v4) EIP IP traffic (v4) (errors) ICMP ICMP traffic (v4) EICMP ICMP traffic (v4) (errors) TCP TCP traffic (v4) ETCP TCP traffic (v4) (errors) UDP UDP traffic (v4) SOCK6 Sockets (v6) IP6 IP traffic (v6) EIP6 IP traffic (v6) (errors) ICMP6 ICMP traffic (v6) EICMP6 ICMP traffic (v6) (errors) UDP6 UDP traffic (v6) -q Queue length and load average statistics -r Memory utilization statistics -R Memory statistics -S Swap space utilization statistics -u [ ALL ] CPU utilization statistics -v Kernel table statistics -w Task creation and system switching statistics -W Swapping statistics -y TTY device statistics |
Example :
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[email protected]:$ sar |
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sar -u 2 5 Report CPU utilization for each 2 seconds. 5 lines are dis- played. sar -I 14 -o int14.file 2 10 Report statistics on IRQ 14 for each 2 seconds. 10 lines are displayed. Data are stored in a file called int14.file. sar -r -n DEV -f /var/log/sa/sa Display memory, swap space and network statistics saved in daily data file ’sa16’. sar -A Display all the statistics saved in current daily data file. |
sar command, sar usage, sar details, sar examples
spamd crashed, cpanel spamd re-installation on the server spamd crashed, cpanel spamd re-installation on the server When you see the exim panic log @ /var/log/exim_paniclog you will see the below errors
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2015-05-16 0225:49 [373954] 1YuIfl-ZHW-GP spam acl condition: error reading from spamd socket: Connection timed out 2015-05-16 0225:53 [373790] 1YuIfm-ZEs-27 spam acl condition: error reading from spamd socket: Connection timed out 2015-05-16 0225:53 [373791] 1YuIfl-ZEt-VC spam acl condition: error reading from spamd socket: Connection timed out 2015-05-16 0225:53 [373921] 1YuIfm-ZGz-1s spam acl condition: error reading from spamd socket: Connection timed out 2015-05-16 0225:53 [373788] 1YuIfm-ZEq-5U spam acl condition: error reading from spamd socket: Connection timed out 2015-05-16 0225:55 [373948] 1YuIfm-ZHQ-D3 spam acl condition: error reading from spamd socket: Connection timed out 2015-05-16 0225:58 [375262] 1YuIgA-Zcc-3z spam acl condition: error reading from spamd socket: Connection timed out 2015-05-16 0225:58 [374865] 1YuIg5-ZWD-Js spam acl condition: error reading from spamd socket: Connection timed out 2015-05-16 0226:10 [373805] 1YuIfm-ZF7-Lp spam acl condition: error reading from spamd socket: Connection timed out |
When we try to restart the service using. No response or solution to the problem.
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[email protected] # /scripts/restartsrv_spamd |
the solution is to reinstall the spamassasin By the Below commands, we can successfully reinstall or upgrade the spamd or SpamAssasin
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/scripts/perlinstaller Digest::SHA1 /scripts/perlinstaller --force Mail::SpamAssassin /etc/rc.d/init.d/exim restart |
Alternatively, You can also do the upcp by forcing to upgrade the applications.
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[email protected] # /scripts/upcp --force |
This will reinstall and upgrade even the versions are upto date. Drop in your Read more…