Mirror a web site using wget
Answer:
wget is a standard program came with most Linux distributions. It allows you to create a mirror (backup) of a web site easily using the following command.
# wget -m -k -K -E http://www.example.com
Aug 092010
Jul 312010
Simple timer in Linux
Answer:
To create a simple timer and return when time-up, use the following command.
# time read -t 3
real 0m3.000s
user 0m0.000s
sys 0m0.000s
Jul 302010
Remove packages and config files in Ubuntu
Answer:
If you want to remove a package in Ubuntu, you can use apt-get remove, e.g.
# sudo apt-get remove php5
However, the config files will NOT be removed.
To remove the config files also, you can use apt-get purge, e.g.
# sudo apt-get purge php5
Jul 282010
What is the difference between ip address 0.0.0.0 and 127.0.0.1?
Answer:
Sometimes when using the netstat command, which print out something like
# netstat -ntpl
(No info could be read for "-p": geteuid()=1001 but you should be root.)
Active Internet connections (only servers)
Proto Recv-Q Send-Q Local Address Foreign Address State PID/Program name
tcp 0 0 0.0.0.0:25 0.0.0.0:* LISTEN -
...
What is the real meaning of 0.0.0.0?
In fact, this special IP means "all the IP addresses on the local machine". So if you have seen a service listening on 0.0.0.0, it means you can connect to the service using any IP addresses of the machine.
Jul 132010
How to sum a file of numbers?
Answer:
Assume you have a text file with numbers, one line one number, e.g.
1
2
3
4
5
6
7
8
9
10
You can use the paste and bc command for this tasks.
# paste -sd+ num.txt | bc
55