core-tutorial: trim the section on Inspecting Changes

Back when the core tutorial was written, `log` and `whatchanged`
were scripted Porcelains.  In the "Inspecting Changes" section that
talks about the plumbing commands in the diff family, it made sense
to use `log` and `whatchanged` as good examples of the use of these
plumbing commands, and because even these scripted Porcelains were
novelty (there wasn't the new end-user tutorial written), it made
some sense to illustrate uses of the `git log` (and `git
whatchanged`) scripted Porcelain commands.

But we no longer have scripted `log` and `whatchanged` to serve as
examples, and this document is not where the end users learn what
`git log` command is about.  Stop at briefly mentioning the
possibility of combining rev-list with diff-tree to build your own
log, and leave the end-user documentation of `log` to the new
tutorial and the user manual.

Also resurrect the last version of `git-log`, `git-whatchanged`, and
`git-show` to serve as examples to contrib/examples/ directory.

While at it, remove 'whatchanged' from a list of sample commands
that are affected by GIT_FLUSH environment variable. This is not
meant to be an exhaustive list but as a list of typical ones, and an
old command that is kept primarily for backward compatibility does
not belong to it.

Helped-by: Matthieu Moy <Matthieu.Moy@grenoble-inp.fr>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

2 files changed, 43 insertions, 0 deletions

diff --git a/contrib/examples/git-log.sh b/contrib/examples/git-log.sh
new file mode 100755
index 000000000..c2ea71cf1
--- /dev/null
+++ b/contrib/examples/git-log.sh
@@ -0,0 +1,15 @@
+#!/bin/sh
+#
+# Copyright (c) 2005 Linus Torvalds
+#
+
+USAGE='[--max-count=<n>] [<since>..<limit>] [--pretty=<format>] [git-rev-list options]'
+SUBDIRECTORY_OK='Yes'
+. git-sh-setup
+
+revs=$(git-rev-parse --revs-only --no-flags --default HEAD "$@") || exit
+[ "$revs" ] || {
+	die "No HEAD ref"
+}
+git-rev-list --pretty $(git-rev-parse --default HEAD "$@") |
+LESS=-S ${PAGER:-less}
diff --git a/contrib/examples/git-whatchanged.sh b/contrib/examples/git-whatchanged.sh
new file mode 100755
index 000000000..1fb9feb34
--- /dev/null
+++ b/contrib/examples/git-whatchanged.sh
@@ -0,0 +1,28 @@
+#!/bin/sh
+
+USAGE='[-p] [--max-count=<n>] [<since>..<limit>] [--pretty=<format>] [-m] [git-diff-tree options] [git-rev-list options]'
+SUBDIRECTORY_OK='Yes'
+. git-sh-setup
+
+diff_tree_flags=$(git-rev-parse --sq --no-revs --flags "$@") || exit
+case "$0" in
+*whatchanged)
+	count=
+	test -z "$diff_tree_flags" &&
+		diff_tree_flags=$(git-repo-config --get whatchanged.difftree)
+	diff_tree_default_flags='-c -M --abbrev' ;;
+*show)
+	count=-n1
+	test -z "$diff_tree_flags" &&
+		diff_tree_flags=$(git-repo-config --get show.difftree)
+	diff_tree_default_flags='--cc --always' ;;
+esac
+test -z "$diff_tree_flags" &&
+	diff_tree_flags="$diff_tree_default_flags"
+
+rev_list_args=$(git-rev-parse --sq --default HEAD --revs-only "$@") &&
+diff_tree_args=$(git-rev-parse --sq --no-revs --no-flags "$@") &&
+
+eval "git-rev-list $count $rev_list_args" |
+eval "git-diff-tree --stdin --pretty -r $diff_tree_flags $diff_tree_args" |
+LESS="$LESS -S" ${PAGER:-less}