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twaugh merged 1 commit into from
Oct 17, 2025
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doc: improve grepdiff documentation with better examples #146

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26 changes: 18 additions & 8 deletions doc/patchutils.xml
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Expand Up @@ -956,8 +956,7 @@ patch.file]]></screen></para>
<para>For CI/CD systems that need line numbers matching the original
diff context (useful for error reporting), use the original-* variants:

<screen><![CDATA[grepdiff pattern --output-matching=hunk \
--as-numbered-lines=original-after patch.file]]></screen></para>
<screen><![CDATA[filterdiff --as-numbered-lines=original-after patch.file]]></screen></para>
<para>Filterdiff can also be used to convert between unified
and context format diffs:

Expand Down Expand Up @@ -2100,12 +2099,6 @@ This is the same as gitdiff but uses git show instead of git diff.
are used instead of POSIX regular expressions, and the <option>-E</option>
option has no effect since PCRE already supports extended regular
expression features by default.</para>
<para>For example, to see the patches in
<filename>my.patch</filename> which contain the regular
expression <quote>pf_gfp_mask</quote>, use:

<screen><![CDATA[grepdiff pf_gfp_mask my.patch | \
xargs -rn1 filterdiff my.patch -i]]></screen></para>
<para>You can use unified, context, and Git format diffs with
this program. Git format includes support for binary files,
file renames, permission mode changes, and other Git-specific
Expand Down Expand Up @@ -2409,6 +2402,23 @@ This is the same as gitdiff but uses git show instead of git diff.
</refsect1>
<refsect1>
<title>Examples</title>
<para>To quickly identify which files in a large patch contain
memory allocation changes (useful for code review):

<screen><![CDATA[grepdiff "malloc\|free\|realloc" large-patch.diff]]></screen></para>
<para>This shows only the filenames, giving you a quick overview
without being overwhelmed by diff content.</para>
<para>To see the actual hunks containing the pattern:

<screen><![CDATA[grepdiff --output-matching=hunk "malloc" patch.diff]]></screen></para>
<para>To see complete file diffs for files containing the pattern:

<screen><![CDATA[grepdiff --output-matching=file "malloc" patch.diff]]></screen></para>
<para>For CI/CD systems that need line numbers matching the original
diff context (useful for error reporting):

<screen><![CDATA[grepdiff pattern --output-matching=hunk \
--as-numbered-lines=original-after patch.file]]></screen></para>
<para>Git format diffs are fully supported. For example, to find
files in a git patch that contain changes to malloc calls:

Expand Down