Password free secure copy // SCP & SSH

April 24, 2006 | In Linux | 4 Comments

Password – free login for scp http://www.linuxjournal.com/article/8600

Pass on Passwords with scp

By Dave Sirof on Thu, 2005-10-06 01:00. Security Learn how to propagate files quickly and do backups easily when you set up scp to work without needing passwords.

In this article, I show you how to use the scp (secure copy) command without needing to use passwords. I then show you how to use this command in two scripts. One script lets you copy a file to multiple Linux boxes on your network, and the other allows you to back up all of your Linux boxes easily.

If you’re a Linux sysadmin, you frequently need to copy files from one Linux box to another. Or, you may need to distribute a file to multiple boxes. You could use FTP, but using scp has many advantages. For instance, scp is much more secure than FTP. scp travels across the LAN/WAN encrypted, while FTP uses clear text, even for passwords.

But what I like best about scp is it’s easily scriptable. Suppose you need to distribute a file to 100 Linux boxes. I’d rather write a script to do this than type 100 sets of copy commands. If you use FTP in your script, things can get messy, because each Linux box you log into is going to ask for a password. But if you use scp in your script, you can set things up so the remote Linux boxes don’t ask for a password. Believe it or not, this actually is much more secure than using FTP.

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Excel – copying formulas

April 21, 2006 | In Other Tech | 3 Comments

Move or copy a formula
When you move a formula, the cell references within the formula do not change. When you copy a formula, absolute cell references do not change; relative cell references will change. For more information about absolute and relative references, click .

Select the cell that contains the formula you want to move or copy.

Point to the border of the selection.

To move the cell, drag the selection to the upper-left cell of the paste area. Microsoft Excel replaces any existing data in the paste area.
To copy the cell, hold down CTRL as you drag.

Tip You can also copy formulas into adjacent cells by using the fill handle. Select the cell that contains the formula, and then drag the fill handle over the range you want to fill.

*** Absolute cell reference= exact address that does not move when copied – denoted by $ as in $A$1 . Can mix references as in A$1.

Count Unix Files

April 20, 2006 | In Linux | No Comments

Count, Sort and Compare Unix Files
� March 21, 1994	B-18

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Unix has several utilities to help count, sort and compare files. To illustrate these utilities, assume we have two files, phonesA and phonesB. Each contains a list of telephone locals and people’s names:

	phonesA							phonesB
4678	George Smith						4221	Susan Wilson
2870	Bill Anderson						3895	Jan Smythe
3717	Joan Brown						3664	John Lee
4221	Susan Wilson

Counting characters, words and lines

The command wc will count the number of lines, words, and characters in a file. To count the file phonesA, type

wc phonesA

The result is

4        12        75 phonesA

The first number is the number of lines in the file, the second is the number of words and the third is the number of characters.

Use wc to count multiple files by giving several filenames as arguments to the command. For example, to count both phonesA and phonesB, type

wc phonesA phonesB

The result is

4        12        75 phonesA
3         9        51 phonesB
7        21       126 total

wc counts lines, words and characters in each file, and totals each of these three items for the two files.

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