That's Vimprovement! A Better vi
Vim has some interesting searching options. The first is the incremental searching option, which is enabled with the command:
Normally when you do a search, say for include, you would enter the entire command: /include<CR> and Vim would start searching for the string. When incremental searching is enabled, Vim starts searching when you type the first character of the search. In other words, when you type /i, Vim searches for the first “i” in the text. Type the next character “n”, for /in and Vim looks for “in”. As you type each character the search moves on (if needed) to find the string that you've typed so far.
The other major innovation in searching is the highlight search (hlsearch) option. If this is enabled, then when Vim finds a string that matches a search, it highlights it. Not only is the current match highlighted, but all matches are highlighted.
This is useful if you're searching for a misspelled variable name or word, because all occurrences of the incorrect word are highlighted.
If you want highlighting to temporarily disappear, you can issue the the :nohl command. This clears the highlighting until the next search command is entered.
Vim also maintains a search history. Let's say you've done a number of searches. Now press / to start a search, and then the <UP> key. The previous search is displayed. Press <UP> again, and you get the next oldest search. Thus using the <UP> and <DOWN> keys you can scroll through a set of your recent searches.
One of the most powerful commands in Vim is the . (dot) command. It repeats your last edit. But this command is limited. It will only repeat a single command.
But what if you have something more complex to do? That's where Vim's keyboard macros come in. They allow you to record a series of commands in a register and then execute them.
To see how this works, let's suppose you have the following lines that you want to edit:
stdio.h time.h unistd.h stdlib.h
You want to make each of these into a #include line, e.g., #include <stdio.h>
You start by entering the command qa. This causes all subsequent commands to be recorded in register a. (Any register from a to z can be used.)
Next do the edits. Go to the beginning of the line (^) insert #include <, then finish by adding a > to the end of the line. Finally go down a line to be ready for the next edit.
All these commands are now recorded in the a register. The q command tells Vim to stop recording. The text now looks like:
#include <stdio.h> time.h unistd.h stdlib.h
with the cursor positioned on the second line. To execute the macro, use the command @a. The results are:
#include <stdio.h> #include <time.h> unistd.h stdlib.hThe @ command takes a repeat, so you can finish off our work using the 2@a command.
#include <stdio.h> #include <time.h> #include <unistd.h> #include <stdlib.h>
The command ctags (which comes with Vim) can be used to generate a program table of contents for a set of C files. (This is now a tags file.)
A typical ctags command is:
This creates a tags file containing the location of all the functions in the C files in the current directory.
Once generated the tags file can be of great use to people editing with Vim.
Let's suppose you are editing a file and are looking at the read_paragraph function. As you go through the code you discover that read_paragraph calls read_sentence. You'd like to see what this function does.
If you position the cursor on the function name, and press CTRL-], Vim jumps to the definition of that function. You quickly discover that read_sentence calls read_word, so you position the cursor over read_word and press CTRL-]. Again the editor jumps to the definition of that function.
Vim keeps track of where you've been through the use of tag stack. To see where you are in this list, use the :tags command.
:tags # TO tag FROM line in file/text 1 1 read_sentence 3 read_sentence(); 2 1 read_word 8 read_word(); >
In this example, we've gone from read_word (not listed), to read_sentence and then read_word. To go back, use the CTRL-T command. It pops you up one level in the tag stack.
Practical Task Scheduling Deployment
July 20, 2016 12:00 pm CDT
One of the best things about the UNIX environment (aside from being stable and efficient) is the vast array of software tools available to help you do your job. Traditionally, a UNIX tool does only one thing, but does that one thing very well. For example, grep is very easy to use and can search vast amounts of data quickly. The find tool can find a particular file or files based on all kinds of criteria. It's pretty easy to string these tools together to build even more powerful tools, such as a tool that finds all of the .log files in the /home directory and searches each one for a particular entry. This erector-set mentality allows UNIX system administrators to seem to always have the right tool for the job.
Cron traditionally has been considered another such a tool for job scheduling, but is it enough? This webinar considers that very question. The first part builds on a previous Geek Guide, Beyond Cron, and briefly describes how to know when it might be time to consider upgrading your job scheduling infrastructure. The second part presents an actual planning and implementation framework.
Join Linux Journal's Mike Diehl and Pat Cameron of Help Systems.
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With all the industry talk about the benefits of Linux on Power and all the performance advantages offered by its open architecture, you may be considering a move in that direction. If you are thinking about analytics, big data and cloud computing, you would be right to evaluate Power. The idea of using commodity x86 hardware and replacing it every three years is an outdated cost model. It doesn’t consider the total cost of ownership, and it doesn’t consider the advantage of real processing power, high-availability and multithreading like a demon.
This ebook takes a look at some of the practical applications of the Linux on Power platform and ways you might bring all the performance power of this open architecture to bear for your organization. There are no smoke and mirrors here—just hard, cold, empirical evidence provided by independent sources. I also consider some innovative ways Linux on Power will be used in the future.Get the Guide