grepdiff

grepdiff [options] regexp [files…]

-0, --zero-files
    Separate filenames with NUL instead of newline

-1, --first-match
    Stop after first matching file

-C NUM, --context=NUM
    Set context lines shown around hunks

-h, --hunk-only
    Print only hunk headers/body, no filenames

-i, --ignore-case
    Ignore case in regex matching

-I PATTERN, --include-from=PATTERN
    Include only hunks from files matching PATTERN

-L LABEL, --label=LABEL
    Use LABEL for filenames instead of actual

-n, --line-number
    Prefix lines with numbers from original files

-N, --new-file
    Treat absent files as empty

-q, --quiet
    Suppress output; set exit status only

-r, --reverse
    Match only on removed (-) lines

-s, --stats
    Print match statistics instead of hunks

-t, --toggle
    Invert match: added or removed lines

-v, --invert-match
    Select hunks NOT matching regex

-x PATTERN, --exclude-from=PATTERN
    Exclude hunks from files matching PATTERN

-z, --de-ANSI
    Ignore ANSI color escapes in diffs

grepdiff scans unified diff files (output from diff -u) and prints only the hunks (diff chunks) containing lines that match a given regular expression. Unlike plain grep, it understands diff format, reprinting entire matching hunks with headers, context, added (+), and removed (-) lines intact.

This is ideal for searching large patches or quilt series for changes to specific code, functions, or strings. For example, find all modifications to a variable without irrelevant noise. It supports file inclusion/exclusion, case-insensitivity, statistics, and more.

Input can be files or stdin; output mimics original patch structure for easy patch application or review. Part of patchutils package, enhancing patch workflows.

Works best on unified diffs; may mishandle context/normal diffs. Regex is basic POSIX; no Perl extensions. Requires patchutils package.

grepdiff -i 'foo.*bar' changes.patch
Find hunks mentioning 'foo'/'bar' case-insensitive.

grepdiff -n --include=*.c 'malloc' ../patches/
Line-numbered C file changes with 'malloc'.

0: matches found; 1: no matches; 2: errors.

Developed by Tim Waugh; first in patchutils 0.2.20 (2003). Evolved for quilt/patch workflows; stable, minimal changes since.

filterdiff(1), lsdiff(1), diffstat(1), patch(1), grep(1)