What do "Cc:" and "Bcc:" mean?

Cc: stands for "carbon copy." Anyone listed in the Cc: field of a message receives a copy of that message when you send it. All other recipients of that message can see that the person you designated as a Cc: recipient received a copy of the message.

Bcc: stands for "blind carbon copy." This is similar to the Cc: feature, except that Bcc: recipients are invisible to all the other recipients of the message (including other Bcc: recipients). For example, if you send a message To: johndoe@yahoo.com and Bcc: janedoe@yahoo.com, then johndoe sees himself as the message's only recipient. Janedoe, on the other hand, is "in the know"—she can see that you sent the message To: johndoe, and that you blind-copied her. To add an entry in the Bcc: field, click the "Show BCC" link to the right of the "To:" field.

What are seeds and leechers (peers) in torrents?

Number of seeds and leechers (peers) play an important role in determining the download speed of torrent file. So what exactly is meaning of torrents (bittorrent, utorrent) seeds and leechers?

What are seeds?
A seed is a client that has a complete copy of the data of a certain torrent. Once your BitTorrent client finishes downloading, it will remain open until you click the Finish button (or otherwise close it). This is known as being a seed or seeding.

What are leechers?
A leecher is a client that is currently downloading the data of a torrent. A leecher does not have the complete file, otherwise it would be called a seed.
Conclusion:
Seeds have the complete file and are actively sharing ... peers are downloading the file and have part of it and usually are sharing pieces also ... high numbers of each are best for speed ... low numbers of seeds and high peers will make it slow .. low numbers on each will make it slow ......

Unix version using command

How to check Unix version using command prompt?

surya# cat /etc/*-release

SUSE Linux Enterprise Server 12 (x86_64)
VERSION = 12


surya# cat /proc/version 

Linux version 2.6.16.60-0.58.1.3835.0.PTF.638363-smp 

How to find out LAN card speed in linux ?

To Find full or half duplex speed:

You can use dmesg command to find out your duplex mode:


   # dmesg | grep -i duplex


O/P: 

eth0: link up, 1000Mbps, full-duplex, lpa 0x45E1


So we can come to know that it has 

1. One NIC card, i.e, etho.  if it has 2 NIC cards , it will show eth1 
2. It is 1000Mbps speed
3. Communication is full duplex mode.


Use ethtool to display or change ethernet card settings.  To display duplex speed.


# ethtool eth0

Output:

Settings for eth0:
        Supported ports: [ TP ]
        Supported link modes:   10baseT/Half 10baseT/Full
                                          100baseT/Half 100baseT/Full
                                          1000baseT/Full
        Supports auto-negotiation: Yes
        Advertised link modes:  10baseT/Half   10baseT/Full
                                          100baseT/Half  100baseT/Full
                                          1000baseT/Full
        Advertised auto-negotiation: Yes
        Speed: 1000Mb/s
        Duplex: Full
        Port: Twisted Pair
        PHYAD: 0
        Transceiver: internal
        Auto-negotiation: on
        Supports Wake-on: umbg
        Wake-on: g
        Current message level: 0x00000007 (7)
        Link detected: yes

Explanation:

So we come to know that , eth0 supports 10baseT/Half, 10baseT/Full, 100baseT/Half, 100baseT/Full and  1000baseT/Full.

But the network configured as 1000Mbps , Full duplex mode.

We can also use mii-tool to find out your duplex mode.   Type following command at shell prompt:

# mii-tool 

Output:

 eth0: negotiated 100baseTx-FD flow-control, link ok


Remember:

100baseTx-FD: 100Mbps full duplex (FD)
100baseTx-HD: 100Mbps half duplex (HD)
10baseT-FD:     10Mbps full duplex (FD)
10baseT-HD:    10Mbps half duplex (HD)