On computer filesystems, different files and directories have permissions that specify who and what can read, write, modify and access them. This is important because WordPress may need access to write to files in your wp-content directory to enable certain functions.

Permission Modes

  7       5     5
 user   group  world
 r+w+x  r+x    r+x
 4+2+1  4+0+1  4+0+1  = 755

The permission mode is computed by adding up the following values for the user, the file group, and for everyone else. The diagram shows how.

• Read 4 – Allowed to read files
• Write 2 – Allowed to write/modify files
• eXecute1 – Read/write/delete/modify/directory

  7       4      4
 user   group  world
 r+w+x    r      r
 4+2+1  4+0+0  4+0+0  = 744

Example Permission Modes

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ติดตั้ง DHCP Server เพื่อทำให้ server แจกไอพีให้กับเครื่องลูกข่าย

# apt-get install dhcp 3-server
ตั้งค่าให้ DHCP Server แจกไอพี
# nano /etc/dhcp 3/dhcpd.conf
ตัวอย่างการตั้งค่า
subnet 192.168.10.0 netmask 255.255.255.0 {
range 192.168.10.10 192.168.10.250;
option domain-name-server 203.113.24.199 , 203.113.127.199;
option domain-name “homgun.com” ;
option routers 192.168.10.1 ;
option broadcast–address 192.168.10.255 ;
default–lease–time 600 ;
max–lease–time 7200 ;
}
สั่งให้ dhcp เริ่มทำงานใหม่

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Enable SNMP Community Strings

This procedure is the same for both routers and Cisco IOS software-based XL Catalyst Switches.

1. Telnet to the router:
   

   prompt#telnet 172.16.99.20

2. Enter the enable password at the prompt in order to enter the enable mode:
   

   Router>enable 
   Password: 
   Router#

3. Display the running configuration and look for the SNMP information:
   

   Router#show running-config 
   Building configuration... 
   .... 
   .... 
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code

In order to “zip” a directory, the correct command would be

tar -zcvf archive.tar.gz directory/