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How to check commit comments on SVN Commit

How to check commit comments on SVN Commit


If you are using Subversion/CVS, you might have come across the issue where multiple developers working on a set of files are committing without any comments.

Subversion’s hook scripts provide a powerful way to associate actions with repository events. For example, the pre-commit hook allows you to check — and possibly abort — a transaction before it actually gets committed. I will provide you now two easy Unix bash scripts  that avoid bad developer behaviors:

  • The first one “” is for checking that nobody submit an empty SVN commit comment
  • The second one “” is able to enforce SVN commit comment pattern using regular expressions

Creating and Installing a Hook Script

Your Subversion repository already has some template hook scripts. For example, the pre-commit template is in PATH_TO_REPOS/hooks/pre-commit.tmpl. These templates contain instructions on what the hook script does and what parameters it can expect.

You can hook your own script on the following events

  • start-commit Before the commit transaction starts
  • pre-commit After the commit transaction starts but before the transaction is committed
  • post-commit After the commit transaction completes
  • pre-revprop-change Before a revision property is changed Repository Path,
  • post-revprop-change: After a revision property is changed Repository Path
  • pre-lock:  Before the lock being acquired
  • post-lock:  After the lock being acquired

You’ll find examples in the hook directory named

  • post-commit.tmpl
  • pre-unlock.tmpl
  • post-lock.tmpl
  • pre-commit.tmpl
  • start-commit.tmpl
  • post-revprop-change.tmpl
  • pre-lock.tmpl
  • post-unlock.tmpl
  • pre-revprop-change.tmpl

If you cant find them, brute force your server to locate them

# find / –name pre-commit


# locate pre-commit

On Debian you will find them at


Create a file pre-commit with that content, nothing force you to put a huge bash script in pre-commit. In my example below, I prefer to divide pre-commit checks in multiple files. The pre-commit hook gives you a way to catch the transaction before it becomes a revision. Subversion passes this hook two parameters:

  1. the path to the root of the repository
  2. the transaction identifier
#!/bin/sh set -e /data/svn-repos/{yourRepository}/hooks/ "$1" "$2" /data/svn-repos/{yourRepository}/hooks/ "$1" "$2"

Note that after installation, every commit will run these two scripts. Check your permissions, scripts have to be runnable for the user (www-data on debian)

Avoid empty comment in SVN commits

Save this file in /data/svn-repos/{yourRepository}/hooks/

#!/bin/sh REPOS="$1" TXN="$2" SVNLOOK=/usr/bin/svnlook  if [`$SVNLOOK log -t $TXN $REPOS` != ""]; then   echo "" 1>&2   echo "*** Your commit has been blocked because you did not give any log message or your log message was too short." 1>&2   echo "Please write a log message describing the purpose of your changes and then try committing again." 1>&2   exit 1 else   exit 0 fi

Example in Eclipse, if you break the rule


Enforce SVN commit comment pattern using regular expressions

Save this file in /data/svn-repos/{yourRepository}/hooks/

This script use Bash script REGEX capabilities, I check against what could be a typical JIRA issues entry

If any developer try to use a commit statement not starting with for example PRODUCT-xxxx, the commit will be blocked.

#!/bin/sh REPOS="$1" TXN="$2" SVNLOOK=/usr/bin/svnlook regex="PRODUCT-[0-9]*"  if [[ `$SVNLOOK log -t $TXN $REPOS` =~ ${regex} ]]; then   exit 0 else   echo "" 1>&2   echo "*** Your commit has been blocked because you give an invalid commit comment" 1>&2   echo "Please make your commit comment start with PRODUCT-XXX" 1>&2  exit 1 fi

Example in Eclipse, if you break the rule


Want more?

You can automated code reviews with Checkstyle using pre-commit script and so Stop rule-breaking code before it enters your code base!

References List of some Hook scripts examples written in python/bash

About The Author

Cédric Walter

I worked with various Insurances companies across Switzerland on online applications handling billion premium volumes. I love to continuously spark my creativity in many different and challenging open-source projects fueled by my great passion for innovation and blockchain technology.In my technical role as a senior software engineer and Blockchain consultant, I help to define and implement innovative solutions in the scope of both blockchain and traditional products, solutions, and services. I can support the full spectrum of software development activities, starting from analyzing ideas and business cases and up to the production deployment of the solutions.I'm the Founder and CEO of Disruptr GmbH.