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This article mainly introduces "what are the methods to improve the efficiency of text search in the CentOS system". In the daily operation, I believe that many people have doubts about the methods to improve the efficiency of text search in the CentOS system. The editor consulted all kinds of materials and sorted out simple and easy-to-use methods of operation. I hope it will be helpful to answer the questions of "what are the methods to improve the efficiency of text search in the CentOS system?" Next, please follow the editor to study!

For system administrators or programmers, grep-type tools are probably the most popular when you need to search for specific text or patterns in directories with complex configurations or in large source trees.

If grep is one of your favorite tools, then you may prefer ack. Ack is a Perl-based command-line tool similar to grep, but it is faster to search and more capable than grep. Especially if you are a programmer, I highly recommend that you use ack instead of grep.

The use of ack is ideal for code search, so programmers can make complex queries in the source tree with fewer keystrokes.

Characteristics of ack

Some very powerful features of ack:

Search the current working directory by default

Default recursive search subdirectory

Ignore metadata directories, such as .svn, .git, CSV, etc.

Ignore binaries (e.g. pdf,image,coredumps) and backup files (e.g. foo~,*.swp)

Print a line number in the search results to help you find the target code

Can search for a specific file type (such as Perl,C++,Makefile), which can have multiple file suffixes

Highlight search results

Advanced regular expressions that support Perl are more expressive than the GNU regular expressions used by grep.

Ack is generally faster than grep in terms of search speed. Ack's speed is as long as it's shown in its built-in file type filter. During the search, ack maintains a list of approved file types while skipping unknown or unnecessary file types. It also avoids checking redundant metadata directories.

Install ack on Linux

Although ack is a standard package and readily available in most Linux distributions (for example, ack-grep packages in debian-based systems and ack packages in Redhat-based systems), the ack version bundled with the distribution is still 1.x, while ack2.0 has been released and has more features.

So I'm going to download it from the official website and install ack.

Conveniently, ack is available as a separate Perl script on the official website, which integrates all the modules you need to rely on. Therefore, you do not need to install additional Perl modules to run the script.

To install ack on your Linux system, go to the official website to download the latest version of ack. At the time of writing, the latest version is 2.12

$wget http://beyondgrep.com/ack-2.12-single-file $sudo mv ack-2.12-single-file / usr/local/bin/ack $sudo chmod 0755 / usr/local/bin/ack

It should be noted that in Debian-based systems, there is a separate package called ack (Chinese Code Converter). So if you happen to use that package, you have to rename ack to avoid naming conflicts.

Use cases for ack

1. Recursively search for the word "eat" in the current directory and do not match a string like "feature" or "eating":

$ack-w eat

two。 Search for all metacharacters of the string'$path=.', 'with special characters (such as' $','.') It needs to be matched literally:

$ack-Q'$path=.' / etc

3. Except for the dowloads directory, search all directories for the word "about":

$ack about-ignore-dir=downloads

4. Search only for PHP files that contain the 'protected' word, and then integrate the search results by file name to print the search results for each file:

$ack-php-group protected

5. Gets the file name of the Makefile that contains the 'CFLAG' keyword. The file name is * .mk, and all of makefile,Makefile,GNUmakefile are under consideration:

$ack-- make-l CFLAG

6. Highlight the matching string when displaying the entire log file:

$tail-f / var/log/syslog | ack-- passthru 192.168.1.10

7. To get the file filtering types supported by ack, run:

$ack-help-type

At this point, the study of "what are the ways to improve the efficiency of text search in CentOS system" is over. I hope to be able to solve your doubts. The collocation of theory and practice can better help you learn, go and try it! If you want to continue to learn more related knowledge, please continue to follow the website, the editor will continue to work hard to bring you more practical articles!

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