editdiff

editdiff [options] file1 file2

-c
    Produces a context diff format output, showing several lines of context around changed lines.

-e
    Generates an ed(1) script. This is the default output format.

-f
    Produces a 'full context' diff, which includes context lines for all changes, even if they are not directly adjacent.

-n
    Generates an rcs-style normal diff. This format is similar to the output of diff -n, indicating line numbers for changes.

-u
    Produces a unified diff format output, a compact representation of changes with context.

-V
    Prints the version number of editdiff and exits.

-xregexp
    Ignores chunks of lines that match the extended regular expression regexp. This is useful for ignoring whitespace changes or specific patterns.

editdiff is a Linux command that compares two files, file1 and file2, and generates a script or a diff output that, when applied to file1, transforms it into file2. Its primary and default function is to produce an ed(1) script, which is a series of commands for the ed line editor. This script can then be executed against file1 to achieve the content of file2.

While other diff utilities like diff(1) typically show the differences between files for human readability, editdiff focuses on creating an executable transformation. It is often bundled with the RCS (Revision Control System) suite, where such scripts are useful for maintaining versions and applying changes between them programmatically, though patch(1) has largely superseded ed scripts for general-purpose patching.

editdiff is a niche tool primarily for generating ed(1) scripts. For general-purpose file comparison and patching, diff(1) and patch(1) are far more commonly used and flexible. Its utility is most pronounced in environments or scripts specifically designed to work with ed commands, or within the context of older revision control systems like RCS.

While less common today, editdiff can be useful in scripting scenarios where a precise, line-by-line transformation script is required. For instance, if you need to apply changes to a file without knowing the original content beforehand, an ed script generated by editdiff might be suitable, as it contains direct line editing commands. However, for most modern version control and patching tasks, diff and patch provide more robust and versatile solutions.

editdiff is part of the GNU RCS (Revision Control System) package, which originated in the early 1980s. RCS was one of the earliest and most influential version control systems for single files. editdiff's focus on generating ed scripts reflects the common practice of the time for applying changes programmatically, before the widespread adoption of the more robust and user-friendly patch utility. It continues to be maintained as part of the RCS suite.

diff(1), patch(1), ed(1), rcs(1)