In this article I am going to introduce you to the grep command and how it is used. Once you know this command, your life with the Linux command line will be made much easier.

Limitations

Although grep is a very versatile command to know, it does have its limitations. One of the biggest limitations it has is that it can not search within binary files. That’s all fine, because your typical binary file would be searchable with the application that created said binary file.

Grep also has a line limit of 2048 lines. This means if your file is beyond that, grep will stop searching at the line limit.

Installation

You are in luck. Grep is a tool that comes pre-installed with all Linux distributions. So no installation is required.

Usage

The basic usage of grep is:

grep [OPTIONS] [PATTERN] file

Their are numerous options to use with the Grep command. The more helpful of these options are:

-E Interpret the PATTERN section as an extended regular expression.
-P Interpret the PATTERN section as a Perl regular expression.
-e Use PATTERN as the pattern. If searching a single PATTERN you do not need the -e option. But this option allows you to search for multiple search patterns.
-f  Obtain patterns from a file, one per line.
-i Ignore case.
-c Suppress normal output and only output count of matching lines.
--color Display the matched strings in color.
-n Display the line number associated with the matching entry.

Examples

Let’s take a look at a very basic example first. You want to search the file /etc/test.conf for the string input. The grep command for this would be:

grep input /etc/test.conf

Now, let’s say that test.conf is a larger file and you need to know the line number the string input is on. For this the command would look like:

grep -n input /etc/test.conf

The above output would then include the line number associated with each matching entry. Now, let’s say you wanted to search the same file for both input and output and you want to know the line numbers associated with each. For this the command would look like:

grep -n -e input -e output /etc/test.conf

But what if you only want to know how many times the string input is found in the file /etc/test.conf. For this you could use the command like so:

grep -c input /etc/test.conf

Final thoughts

Grep is one of those commands that you will use time and again, in many, various ways. I always tell new users that, once you reach the point where you begin using the command line, grep is one of the first commands you should master.

There is such a tool – SearchMonkey. SearchMonkey attempts to bridge the gap between Beagle and locate/find by adding a powerful regular expression builder to a GUI searching tool. And SearchMonkey does quite well at this task.

In this article you will learn how to install SearchMonkey and use its powerful regular expression builder to power your searches.

Installing

As you have come to expect, installing SearchMonkey is simple:

1. Open up the Add/Remove Software application.
2. Search for “searchmonkey” (No quotes).
3. Select SearchMonkey for installation.
4. Click Apply.
5. Enjoy.

Once SearchMonkey is installed you will find it in the Accessories sub-menu of the Applications menu.

Using SearchMonkey

Figure 1

When you fire up the SearchMonkey tool the main window will appear (see Figure 1) with three tabs: Basic, Advanced, and Options. For standard searching the Basic tab should be fine. You can not add regular expressions to the Basic tab. Only within the Advanced tab can you take advantage of regular expressions in your searching.

And since anyone can use a basic search GUI, let’s skip right to the good stuff within the Advanced tab.

Advanced searching

Figure 2

When you click on the Advanced tab you will see the regular expression builder right away (see Figure 2). As you can see you can apply regular expressions to the both the file name and the file contents. Let’s walk through the process of creating a regular expression for a search. I want to search all files within /home/jlwallen for any file containing the phrase “Figure” more than once. To do this click on the Expression Builder button for the “Containing” section. When this is clicked this it will open up a new window where the expression can be built.

Figure 3

Here’s how we build our expression. Since our expression will only apply to the contents of the files click the Expression Builder button for the “Contains” section. When the new window appears (see Figure 3) immediately go to the “Text contains” section and select “The phrase” from the drop down. In the text area immediately to the right of that drop down enter  ”Figure” (no quotes). Now select “One or more times” from the “Occurs” drop down. The expression is built, it now has to be added by clicking the “Add” button.

This is where the behavior gets a bit odd. After you push the Add button you have to put the OK button to add the expression to the main search window. The problem is, by pushing the OK button your default web browser will open to the SearchMonkey web page. This has nothing to do with your searching. You can close your web browser (or the tab SearcMonkey opened) without any effect to SearchMonkey. After the web page opens, go back to the SearchMonkey window and click Cancel which will take you back to the main window. Now you should see, the “Containing” section the string “(Figure)+” (no quotes). That is the expression to find all files that contain the string “Figure” (no quotes).

Click Start and you will quickly see the results pile up (given your file system contains files that match the expression.) Depending upon the size of your hard drive, the amount of files/folders on your machine, the complexity of your regular expression, and the speed of your machine the search could take some time.

Final thoughts

That gives you an idea how SearchMonkey is used. If you’re looking for a search tool that gives you far more power at your fingertips than the standard fair, SearchMonkey might be the perfect solution for you. Not only can you search your entire file system, you can create some fairly complex regular expressions to add power to your searching.

The Claws Mail template feature allows you to create specific templates that format your email in precisely the way you want them. Your compositions, your replies, and your forwards can leave your PC laid out exactly the way you want them. And it doesn’t take a programmer or guru to set templates up. You just have to understand the strings used by Claws Mail that allow you to insert specific, pre-configured fields into the body of your email.

Figure 1

You can create templates within one of two windows: “Preferences for current account” or “Preferences” (the former only configures templates for the account being used and the latter configures templates globally). Both of these windows can be opened from within the Configuration menu. Once in either of these windows go to the Templates section where you will find  three tabs (see Figure 1): Compose, Reply, and Forward. The first thing you must do is decide what type of template you want to create. Most often people use the Reply template so they can format how they want their replies to look.

As you can see, in Figure 1, I have already created a template. The template I have created does this when I reply to an email:

The first line of the reply reads In a recent email ORIGINAL_SENDER said the following:

QUOTED_EMAIL

to this REPLY_SENDER says:

BODY_OF_REPLY

A: Because it makes understanding the conversation harder?
Q: What is wrong with top posting?

• Where ORIGINAL_SENDER is who the email came from.
• Where QUOTED_EMAIL is the quoted text of the email you are replying to.
• Where REPLY_SENDER is the full name of the user replying.
• Where BODY_OF_REPLY is the text written in the reply.

You will also notice a bit of snarkiness at the end. ;-)

To achieve this layout I used the following pre-defined tags:

• %N – Original sender.
• \n – New line marker.
• %Q – Quoted message body.
• %af – Full name of sender (me).
• %X – Cursor position.

The %X tag is one of the most interesting of the tags. It is with this tag you define where you want your cursor to be placed when you begin the email. Because Claws Mail defaults to bottom posting, and has no means to change this to top posting, you have to define top posting by using the %X tag. So if I want to always top post in my replies I would create a reply template like this:

%X\n
Is my reply to an email sent by %N, that said:\n
%Q

To get a full list of all the possible tags to use click the Information button inside of the Templates configuration window. You will also notice you can use regular expressions in your templates. The possibilites abound!

Final thoughts

Once you start using templates in Claws Mail you will really begin to see how flexible this application is. Once I started using templates I never looked back to Thunderbird. Have you created a cool template for Claws Mail? If so, share it with your fellow Ghacks readers.