IT Knowledge Base

/IT Knowledge Base

How to check memory usage per process in linux?

When you feel that your linux server is running slow, you properly run top command to check the how many memory have been used. But it just shows the overall memory usage. To show memory usage per process, you can run this command ps aux --sort -rss

By | August 25th, 2018|IT Knowledge Base|0 Comments

Docker Slow On Mac – How to Fix

IMPORTANT NOTE: This solution does not work any more for Mac OS Big Sur or above Docker is a very nice tool for development. If you are a Mac user, you may experience that the connection to docker is extremely slow. Why docker is slow on Mac? As I develop some web-based systems by using [...]

By | April 2nd, 2018|IT Knowledge Base|0 Comments

Upgrade MySQL from 5.5 to 5.7 on Debian

In a few months ago, I tried to Upgrade MySQL from 5.5 to 5.7 on CentOS. Although the upgrade process is successful, it is a little bit terrible experience because all data may be removed. Recently, I have got another request to the same upgrade but in Debian. The process is definitely much easier. I [...]

By | July 19th, 2016|IT Knowledge Base|0 Comments

Upgrade MySQL from 5.5 to 5.7 on CentOS

I have got a task to migrate a system from a CentOS server and another CentOS server. When I imported the MySQL database to the server, I have got the following error: (SQL Error: 1294 SQL State: HY000) - Invalid ON UPDATE clause for 'column_name' field Oh.... DATETIME can use CURRENT_TIMESTAMP on update starting from [...]

By | April 29th, 2016|IT Knowledge Base|0 Comments

CentOS keeps rebooting

Recently, I reboot a CentOS server and get the following errors. /dev/VolGroup00/LogVol00: Superblock last write time is in the future. FIXED. /dev/VolGroup00/LogVol00: contains a file system with errors, check forced ... /dev/VolGroup00/LogVol00: ***** REBOOT LINUX ***** /dev/VolGroup00/LogVol00: 217372/23602656 files (1.1% non-contiguous), 11132951/23609344 blocks Unmounting fiile systems umount: sunrpc: not found umount: /var/lib/nfs/rpc_pipefs: not mounted umount: [...]

By | March 16th, 2016|IT Knowledge Base|1 Comment

Centos: PHP Fatal error: Class ‘SoapClient’ not found in

You may get an error returned from error log (example from CentOS): PHP Fatal error:  Class 'SoapClient' not found in   Create a php file (e.g. info.php) with the following code in your server : <?php phpinfo();?>   Access to the page (e.g. and check whether the soap is installed and enabled Or You [...]

By | January 7th, 2016|IT Knowledge Base|0 Comments

Office for Mac cannot resize window, freeze panel, maximize

I was trapped into the issue for Microsoft Office for Mac that some files (not all files) cannot resize the window, freeze or unfreeze panel and maximize window. It's quite annoying that a very small window size is fixed when working on the document. Issue happen in the platform: Mac OS X EI Capitan Version [...]

By | December 23rd, 2015|IT Knowledge Base|0 Comments

CentOS: apr_sockaddr_info_get() failed for XXXXX

You may get the error when restarting apache. # service httpd restart Stopping httpd: [ OK ] Starting httpd: httpd: apr_sockaddr_info_get() failed for XXXXX httpd: Could not reliably determine the server's fully qualified domain name, using for ServerName It is because of the apache variable ServerName has not been set. In CentOS, you can [...]

By | December 5th, 2015|IT Knowledge Base|0 Comments

How to solve SQLSTATE[HY000] [2002] No such file or directory

Sometimes a MySQL PDO error message below would be got SQLSTATE[HY000] [2002] No such file or directory The error message may be shown due to the line below $db = new PDO('mysql:host=localhost;dbname=db_name;charset=utf8', 'username', 'password'); What's going on? Try to change "localhost" to "" $db = new PDO('mysql:host=;dbname=db_name;charset=utf8', 'username', 'password');   The error message should then [...]

By | February 20th, 2015|IT Knowledge Base|0 Comments