tkdiff is a graphical diff

Diff

In computing, diff is a file comparison utility that outputs the differences between two files. It is typically used to show the changes between one version of a file and a former version of the same file. Diff displays the changes made per line for text files. Modern implementations also...

 viewer based on the Tk framework. It is capable of inter-operating with source-control systems like CVS

Concurrent Versions System

The Concurrent Versions System , also known as the Concurrent Versioning System, is a client-server free software revision control system in the field of software development. Version control system software keeps track of all work and all changes in a set of files, and allows several developers ...

 and Subversion to show the differences between the local copy and the repository version. Such a line-by-line comparison is often considered to be good software engineering

Software engineering

Software Engineering is the application of a systematic, disciplined, quantifiable approach to the development, operation, and maintenance of software, and the study of these approaches; that is, the application of engineering to software...

practice before committing code changes.

Example usage

• tkdiff — to compare the two files and

• tkdiff — to compare the local version of the given file to the most recent version in the CVS/Subversion repository

tkdiff can also compare two older revisions of a file, etc.