Parse `git log` output into a structured CSV using `awk` and regex groups

How to Parse `git log` Output Into a Structured CSV using `awk` and Regex Groups?

Introduction

Anyone who uses Git knows that git log can provide a powerful glimpse into the history of a project. However, analyzing this data can be cumbersome without the proper tools to parse and structure this output. This blog post aims to guide you through using awk along with regular expressions (regex) to turn the git log output into a neatly structured CSV file.

Q1: What requirements should I meet before I start?

A: Ensure you have Git and awk installed on your Linux system. awk is typically pre-installed on most Linux distributions, and Git can be installed via your package manager (e.g., sudo apt install git on Debian/Ubuntu).

Q2: How do I use `git log` to get my initial data?

A: You can customize your git log output format using the --pretty=format: option. This allows you to specify what commit information (like author, date, commit message, etc.) and how it should be structured directly from the git log command.

Q3: Can I see an example of formatting `git log` output?

A: Certainly! If you want to include the commit hash, author, and date, you might use:

git log --pretty=format:'%h,%an,%ad'

This command will print each commit's hash, author name, and date, separated by commas.

Q4: How do I use `awk` to further process this data?

A: awk is excellent for text processing. You can use it to manipulate each line of the git log output, format or filter information, or even match patterns with regex.

Q5: Could you provide an example of how to integrate `awk` with `git log`?

A: Of course! Here’s a simple script that captures the hash, author, and date of each commit, then outputs these into a CSV format:

git log --pretty=format:'%H,%an,%ad' | awk 'BEGIN {FS=","; OFS=","} {print $1, $2, $3}' > gitlog.csv

This script sets both the input and output field separators as commas and simply prints out the fields as they are.

More Simple Examples and Explanations

Before diving into making complex awk scripting, here are some simpler commands to understand the use of regex within awk:

echo "125,John Doe,2021-07-19" | awk 'BEGIN {FS=","} /^125,/ {print $2}'

This will output John Doe if the line starts with "125," and thus demonstrates basic regex use in awk for filtering lines.

Executable Script Demo

Here is a more complex script that also includes the commit message, cleans up the data, and ensures the CSV is well formatted:

git log --pretty=format:'%H||%cn||%ci||%s' |
awk 'BEGIN { FS="||"; OFS=","; print "SHA,Committer,Date,Message" }
     { gsub(/,/, ";", $4); print $1, $2, $3, $4 }' > gitlog.csv

This script replaces commas in commit messages with semicolons to avoid breaking the CSV format.

Conclusion

Parsing git log output using awk and regex is a robust way to organize commit data into a structured format, like CSV. This allows for easier data manipulation or analysis with spreadsheet software or programming languages like Python. With the power of Unix command-line tools at your disposal, manipulating and parsing complex log data can become a simple and streamlined process.

How to Parse git log Output Into a Structured CSV using awk and Regex Groups?

Introduction

Q1: What requirements should I meet before I start?

Q2: How do I use git log to get my initial data?

Q3: Can I see an example of formatting git log output?

Q4: How do I use awk to further process this data?

Q5: Could you provide an example of how to integrate awk with git log?