Temporary tables are useful when you need to do something on the fly. Instead of writing full CREATE TABLE statement and then inserting from another table, you can do the following with one query:
CREATE [TEMPORARY] TABLE [IF NOT EXISTS] tbl_name
Source: http://linuxapachemysqlphp5.blogspot.com/2013/05/create-temporary-table-in-mysql.html
Before creating a swap file, we should check the size of the current swap:
#cat /proc/meminfo | grep SwapTotal
SwapTotal: 9233400 kB
Create a swap file
To create swap file, you will need to use dd command:
#dd if=/dev/zero of=/newswap bs=1024 count=1048576
if=/dev/zero – read from /dev/zero
of=/newswap – write to /newswap
bs=1024 – blocksize in bytes for reading and writing
count=1048576 – swap file size
Source: http://linuxapachemysqlphp5.blogspot.com/2013/05/create-swap-file-in-linux.html
If you want to add cronjob or edit an existing one you can use the crontab command:
#crontab -e
The ‘-e’ param stands for edit. This will open the crontab file for the current logged user. If you want to edit the crontab file for a specific user you need to specify the username:
#crontab -e -u username
Source: http://linuxapachemysqlphp5.blogspot.com/2013/05/add-edit-delete-list-cronjobs-in-linux.html
Sometimes mysql may not use the index you created for some reason. To force mysql to use an index you can use FORCE INDEX.
| FORCE {INDEX|KEY}
[FOR {JOIN|ORDER BY|GROUP BY}] (index_list)
Source: http://linuxapachemysqlphp5.blogspot.com/2013/05/mysql-force-index.html
If you want to remove a password for a specific user, you can use one of the following commands:
#passwd -d username
or
#passwd –delete username
Source: http://linuxapachemysqlphp5.blogspot.com/2013/05/how-to-delete-users-password-in-linux.html
With the ifconfig command you can list all network cards and ip addresses on a linux system.
#ifconfig
eth0 Link encap:Ethernet HWaddr 00:00:00:00:00:00
inet addr:192.168.1.2 Bcast:192.168.1.255 Mask:255.255.255.0
inet6 addr: 0000::000:0000:0000:000/00 Scope:Link
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
RX packets:54367 errors:0 dropped:0 overruns:0 frame:0
TX packets:34504 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:1000
RX bytes:247741252 (247.7 MB) TX bytes:127569007 (127.5 MB)
Interrupt:28 Base address:0x0000lo Link encap:Local Loopback inet addr:127.0.0.1 Mask:255.0.0.0
inet6 addr: ::1/128 Scope:Host
UP LOOPBACK RUNNING MTU:16436 Metric:1
RX packets:2394 errors:0 dropped:0 overruns:0 frame:0
TX packets:2394 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:0
RX bytes:178041 (173.6 KiB) TX bytes:178041 (173.6 KiB)
Source: http://linuxapachemysqlphp5.blogspot.com/2013/05/list-all-ip-addresses-on-linux-system.html
The following MySql error occurs when you try to make operation on two fields with different collations. To check the field collation you can use the show create query:
mysql> show create table words;
CREATE TABLE `words` (
`word` varchar(20) CHARACTER SET utf8 COLLATE utf8_unicode_ci DEFAULT NULL
) ENGINE=MyISAM DEFAULT CHARSET=latin1
Source: http://linuxapachemysqlphp5.blogspot.com/2013/05/error-1271-hy000-illegal-mix-of.html
With the who command you can list the current logged users on a linux system:
# who
user tty7 2013-05-07 09:18 (:0)
roy pts/0 2013-05-07 14:47 (:0.0)
tony pts/1 2013-05-07 14:49 (:0.0)
ana pts/2 2013-05-07 15:18 (:0.0)
Source: http://linuxapachemysqlphp5.blogspot.com/2013/05/find-currently-logged-users-on-linux.html
To check used/available space on each filesystem, use the following command:
#df -h
Source: http://linuxapachemysqlphp5.blogspot.com/2013/04/linux-check-available-space-on-each.html
Navigate to /etc/apache2/sites-available. Create a file with your new domain name and add the following:
#file: mydomain.com
ServerName mydomain.com
DocumentRoot /root/directory/of/site
Source: http://linuxapachemysqlphp5.blogspot.com/2013/04/ubuntu-add-new-domain-subdomain-in.html
linux apache mysql php 