Quickzi: How To List Files with a Certain Date Stamp

Here is a quick tip on how to list files in a directory with a certain date stamp using awk.

Let’s say that you want to list all files stamped with 2008-04-11.

# ls -l | awk '{if($6=="2008-04-11") print $N }'

-rw-r--r-- 1 adam users 0 2008-04-11 16:27 file1
-rw-r--r-- 1 adam users 0 2008-04-11 16:27 file2
-rw-r--r-- 1 adam users 0 2008-04-11 16:27 file3

If you want to list only the file names, add an F switch.

# ls -l | awk '{if($6=="2008-04-11") print $NF }'

Quickzi: How To Add a Welcome Message for SSH Users

Here is a quick tip on how to add a welcome message for your SSH users.

If you want users to see a banner welcome message when connecting to your SSH server, you need to turn on the banner configuration of SSHd and then create a banner file.

Step 1:

Create a banner file that contains text you want people to see when connecting to your SSH server.

Create and open the banner file:

# vi /home/adam/banner

Add your text:

This is the banner file for Foogazi.com! Welcome!

Write the file and quit:


Step 2:

Edit sshd_config to set a default banner path.

# vi /etc/ssh/sshd_config

then add the following to the config file:

Banner /path/to/banner

Write the file and quit:


Step 3:

Restart the sshd server.

# /etc/init.d/sshd restart

Step 4:

SSH to your server and test to see if the banner is working:

# ssh adam@foogazi.com
This is the banner file for Foogazi.com! Welcome!

adam@foogazi.com's password:

It’s working!

Quickzi: How To Set Cron to Run Every 5 Minutes

Here is a quick tip on how to run crontab every 5 minutes.

*/5 * * * * /home/adam/script.sh will execute script.sh every 5 minutes.

Also, here’s a quick guide to understaning the layout of cron:
5 * * * * echo 'Hello'

Also, the Crontab Man page

For further reading on Crontab check out Understand Cron Jobs in 5 Minutes

10 Good UNIX Usage Habits

Michael Stutz has a very nice article on IBM that covers 10 Good UNIX Usage Habits for the command line.

Adopt 10 good habits that improve your UNIX® command line efficiency — and break away from bad usage patterns in the process. This article takes you step-by-step through several good, but too often neglected, techniques for command-line operations. Learn about common errors and how to overcome them, so you can learn exactly why these UNIX habits are worth picking up.

Here is an example:

Make directory trees in a single swipe

Listing 1 illustrates one of the most common bad UNIX habits around: defining directory trees one at a time.

Listing 1. Example of bad habit #1: Defining directory trees individually

~ $ mkdir tmp
~ $ cd tmp
~/tmp $ mkdir a
~/tmp $ cd a
~/tmp/a $ mkdir b
~/tmp/a $cd b
~/tmp/a/b/ $mkdir c
~/tmp/a/b/ $ cd c
~/tmp/a/b/c $

It is so much quicker to use the -p option to mkdir and make all parent directories along with their children in a single command. But even administrators who know about this option are still caught stepping through the subdirectories as they make them on the command line. It is worth your time to conscientiously pick up the good habit:

Listing 2. Example of good habit #1: Defining directory trees with one command

~ $ mkdir -p tmp/a/b/c

You can use this option to make entire complex directory trees, which are great to use inside scripts; not just simple hierarchies. For example:

Listing 3. Another example of good habit #1: Defining complex directory trees with one command

~ $ mkdir -p project/{lib/ext,bin,src,doc/{html,info,pdf},demo/stat/a}

In the past, the only excuse to define directories individually was that your mkdir implementation did not support this option, but this is no longer true on most systems. IBM, AIX®, mkdir, GNU mkdir, and others that conform to the Single UNIX Specification now have this option.

For the few systems that still lack the capability, use the mkdirhier script (see Resources), which is a wrapper for mkdir that does the same function:
~ $ mkdirhier project/{lib/ext,bin,src,doc/{html,info,pdf},demo/stat/a}

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8 Windows XP Tips & Tricks

Following are a collection of nifty Windows XP Tips & Tricks that I have gathered and used over time.

  • Delete Files Immediately
    This will allow you to delete files from your system without sending them to the recycle bin first.
    Select Start > Run… type gpedit.msc then select User Configuration > Administrative Templates > Windows Components > Windows Explorer then locate the ‘Dsupo not move deleted files to the Recycle Bin‘ setting and set it.

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SSH + Screen = Easy Administration

I have access to a numerous amount of Linux machines for work and personal matters. Instead of having a ton of different SSH or PuTTY windows open, each connected to a server that I administrate, I decided to use screen to connect to all of them, and manage each one in a different screen window.

Before getting into my screen configuration, its also important to note that on top of my screen setup, I have also configured SSH to authenticate via SSH keys, so I wouldn’t have to always type the password when admining from my “playbox”.

Here is how I set up SSH keys.

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