DZone
Thanks for visiting DZone today,
Edit Profile
  • Manage Email Subscriptions
  • How to Post to DZone
  • Article Submission Guidelines
Sign Out View Profile
  • Post an Article
  • Manage My Drafts
Over 2 million developers have joined DZone.
Log In / Join
Refcards Trend Reports
Events Video Library
Refcards
Trend Reports

Events

View Events Video Library

Zones

Culture and Methodologies Agile Career Development Methodologies Team Management
Data Engineering AI/ML Big Data Data Databases IoT
Software Design and Architecture Cloud Architecture Containers Integration Microservices Performance Security
Coding Frameworks Java JavaScript Languages Tools
Testing, Deployment, and Maintenance Deployment DevOps and CI/CD Maintenance Monitoring and Observability Testing, Tools, and Frameworks
Culture and Methodologies
Agile Career Development Methodologies Team Management
Data Engineering
AI/ML Big Data Data Databases IoT
Software Design and Architecture
Cloud Architecture Containers Integration Microservices Performance Security
Coding
Frameworks Java JavaScript Languages Tools
Testing, Deployment, and Maintenance
Deployment DevOps and CI/CD Maintenance Monitoring and Observability Testing, Tools, and Frameworks

How are you handling the data revolution? We want your take on what's real, what's hype, and what's next in the world of data engineering.

Generative AI has transformed nearly every industry. How can you leverage GenAI to improve your productivity and efficiency?

SBOMs are essential to circumventing software supply chain attacks, and they provide visibility into various software components.

Trending

  • Distributed Rate Limiting in Java: A Deep Dive into Bucket4j + PostgreSQL
  • When Agile Teams Fake Progress: The Hidden Danger of Status Over Substance
  • Advanced Argo Rollouts With Datadog Metrics for Progressive Delivery
  • Java Stream API: 3 Things Every Developer Should Know About
  1. DZone
  2. Coding
  3. Languages
  4. Perl as a Better grep

Perl as a Better grep

Can Perl do better than grep when it comes to search files, without overcomplicating everything? The answer might surprise you.

By 
John Cook user avatar
John Cook
·
Jun. 14, 18 · Tutorial
Likes (6)
Comment
Save
Tweet
Share
12.4K Views

Join the DZone community and get the full member experience.

Join For Free

I like Perl's pattern matching features more than Perl as a programming language. I'd like to take advantage of the former without having to go any deeper than necessary into the latter.

The book Minimal Perl is useful in this regard. It has chapters on Perl as a better grep, a better awk, a better sed, and a better find. While Perl is not easy to learn, it might be easier to learn a minimal subset of Perl than to learn each of the separate utilities it could potentially replace. I wrote about this a few years ago and have been thinking about it again recently.

Here, I want to zoom in on Perl as a better grep. What's the minimum Perl you need to know in order to use Perl to search files the way grep would?

By using Perl as your grep, you get to use Perl's more extensive pattern matching features. Also, you get to use one regex syntax rather than wondering about the specifics of numerous regex dialects supported across various programs.

Let RE stand for a generic regular expression. To search a file foo.txt for lines containing the pattern RE, you could type:

perl -wln -e "/RE/ and print;" foo.txt 

The Perl one-liner above requires more typing than using grep would, but you could wrap this code in a shell script if you'd like.

If you'd like to print lines that don't match a regex, change the and to or:

 perl -wln -e "/RE/ or print;" foo.txt

By learning just a little Perl you can customize your search results. For example, if you'd like to just print the part of the line that matched the regex, not the entire line, you could modify the code above to...

 perl -wln -e "/RE/ and print $&;" foo.txt

...because $& is a special variable that holds the result of the latest match.

For daily tips on regular expressions, follow @RegexTip on Twitter.

Perl (programming language) Grep

Published at DZone with permission of John Cook, DZone MVB. See the original article here.

Opinions expressed by DZone contributors are their own.

Partner Resources

×

Comments

The likes didn't load as expected. Please refresh the page and try again.

ABOUT US

  • About DZone
  • Support and feedback
  • Community research
  • Sitemap

ADVERTISE

  • Advertise with DZone

CONTRIBUTE ON DZONE

  • Article Submission Guidelines
  • Become a Contributor
  • Core Program
  • Visit the Writers' Zone

LEGAL

  • Terms of Service
  • Privacy Policy

CONTACT US

  • 3343 Perimeter Hill Drive
  • Suite 100
  • Nashville, TN 37211
  • [email protected]

Let's be friends: