[PATCH 14/23] perf doc: Set man page date to last git commit

[Arnaldo Carvalho de Melo]

From: Ian Rogers <irogers@xxxxxxxxxx>

Currently the man page dates reflect the date the man pages were built.
This patch adjusts the date so that the date is when then man page
last had a commit against it. The date is generated using 'git log'.

Committer testing:

  $ git log -1 --pretty="format:%cd" --date=short tools/perf/Documentation/perf-top.txt
  2020-01-14

Before:

  rm -rf /tmp/build/perf
  mkdir -p /tmp/build/perf
  make -C tools/perf O=/tmp/build/perf/ install
  $ date
  Wed 11 Mar 2020 10:21:19 AM -03
  $ man perf-top | tail -1
  perf                    03/11/2020           PERF-TOP(1)
  $

After:

  rm -rf /tmp/build/perf
  mkdir -p /tmp/build/perf
  make -C tools/perf O=/tmp/build/perf/ install
  $ date
  $ date
  Wed 11 Mar 2020 10:24:06 AM -03
  $ man perf-top | tail -1
  perf                    2020-01-14           PERF-TOP(1)
  $

Signed-off-by: Ian Rogers <irogers@xxxxxxxxxx>
Tested-by: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
Cc: Alexander Shishkin <alexander.shishkin@xxxxxxxxxxxxxxx>
Cc: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
Cc: Jiri Olsa <jolsa@xxxxxxxxxx>
Cc: Mark Rutland <mark.rutland@xxxxxxx>
Cc: Masanari Iida <standby24x7@xxxxxxxxx>
Cc: Mukesh Ojha <mojha@xxxxxxxxxxxxxx>
Cc: Namhyung Kim <namhyung@xxxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Stephane Eranian <eranian@xxxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Link: http://lore.kernel.org/lkml/20200311052110.23132-1-irogers@xxxxxxxxxx
Signed-off-by: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
---
 tools/perf/Documentation/Makefile | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/tools/perf/Documentation/Makefile b/tools/perf/Documentation/Makefile
index adc5a7e44b98..31824d5269cc 100644
--- a/tools/perf/Documentation/Makefile
+++ b/tools/perf/Documentation/Makefile
@@ -295,7 +295,10 @@ $(OUTPUT)%.1 $(OUTPUT)%.5 $(OUTPUT)%.7 : $(OUTPUT)%.xml
 $(OUTPUT)%.xml : %.txt
 	$(QUIET_ASCIIDOC)$(RM) $@+ $@ && \
 	$(ASCIIDOC) -b docbook -d manpage \
-		$(ASCIIDOC_EXTRA) -aperf_version=$(PERF_VERSION) -o $@+ $< && \
+		$(ASCIIDOC_EXTRA) -aperf_version=$(PERF_VERSION) \
+		-aperf_date=$(shell git log -1 --pretty="format:%cd" \
+				--date=short $<) \
+		-o $@+ $< && \
 	mv $@+ $@
 
 XSLT = docbook.xsl
-- 
2.21.1