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Well, I Stumbled upon a command that connects your wired connection from the command line by issuing this in the terminal; "sudo dhclient3 eth0". But there is also a command called "dhclient". Are they the same? Could I issue the same command as; "sudo dhclient eth0?" Could someone clear up newbie on this issue?

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up vote 5 down vote accepted

They are indeed one and the same:

~$ ls -lah /sbin | grep dhclient
lrwxrwxrwx  1 root root      9 2010-12-30 14:38 dhclient -> dhclient3
-rwxr-xr-x  1 root root   402K 2010-08-07 04:49 dhclient3

The arrow indicates that dhclient is a Symbolic Link that points to dhclient3. We can use

test -h /sbin/dhclient
echo $?

to make sure it is; it will return 0, meaning yes.

This is sometimes done to maintain backwards compatibility with older programs and scripts that assume the old command.

If you are writing a program that uses either of those, you should use dhclient3, and manage your dependencies accordingly.

In ls -lah, the arguments mean long listing format, all files, and human readable file sizes. Also, test has nothing to do with symlinks, it's a general utility to test the truth of a statement, the argument -h causes it to work on files, and return True (0) if the file exists and is a symlink.

To find out where the file is, I used the type utility:

type dhclient
dhclient is hashed (/sbin/dhclient)

If you find any two files that aren't symbolically linked, and you suspect they're still the same, you can use a Hash Function to see whether they're the same:

stefano@lenovo:~$ md5sum /sbin/dhclient && md5sum /sbin/dhclient3
fc2491e5c1576783bdc4aa8c5817166e  /sbin/dhclient
fc2491e5c1576783bdc4aa8c5817166e  /sbin/dhclient3
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ah, that clears my doubt. Thank you for the answer. :) – Maverick Jan 2 '11 at 8:24

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