Documentation: explain optional arguments better

Improve the documentation of commands taking optional arguments in two
ways:

* Documents the behavior of '-O' (for grep) and '-S' (for commands
  creating commits) when used without the optional argument.

* Document the syntax of these options.

For the second point, the behavior is documented in gitcli(7), but it is
easy for users to miss, and hard for the same user to understand why e.g.
"git status -u no" does not work.

Document this explicitly in the documentation of each short option having
an optional argument: they are the most error prone since there is no '='
sign between the option and its argument.

Signed-off-by: Matthieu Moy <Matthieu.Moy@imag.fr>
Reviewed-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

9 files changed, 28 insertions, 10 deletions

diff --git a/Documentation/git-am.txt b/Documentation/git-am.txt
index 0d8ba48f79..6b09891db3 100644
--- a/Documentation/git-am.txt
+++ b/Documentation/git-am.txt
@@ -138,7 +138,9 @@ default.   You can use `--no-utf8` to override this.
 
 -S[<keyid>]::
 --gpg-sign[=<keyid>]::
-	GPG-sign commits.
+	GPG-sign commits. The `keyid` argument is optional and
+	defaults to the committer identity; if specified, it must be
+	stuck to the option without a space.
 
 --continue::
 -r::
diff --git a/Documentation/git-cherry-pick.txt b/Documentation/git-cherry-pick.txt
index 66ab29742c..77da29a474 100644
--- a/Documentation/git-cherry-pick.txt
+++ b/Documentation/git-cherry-pick.txt
@@ -103,7 +103,9 @@ effect to your index in a row.
 
 -S[<keyid>]::
 --gpg-sign[=<keyid>]::
-	GPG-sign commits.
+	GPG-sign commits. The `keyid` argument is optional and
+	defaults to the committer identity; if specified, it must be
+	stuck to the option without a space.
 
 --ff::
 	If the current HEAD is the same as the parent of the
diff --git a/Documentation/git-commit-tree.txt b/Documentation/git-commit-tree.txt
index f5f2a8d326..a0b5457304 100644
--- a/Documentation/git-commit-tree.txt
+++ b/Documentation/git-commit-tree.txt
@@ -56,7 +56,9 @@ OPTIONS
 
 -S[<keyid>]::
 --gpg-sign[=<keyid>]::
-	GPG-sign commit.
+	GPG-sign commits. The `keyid` argument is optional and
+	defaults to the committer identity; if specified, it must be
+	stuck to the option without a space.
 
 --no-gpg-sign::
 	Countermand `commit.gpgSign` configuration variable that is
diff --git a/Documentation/git-commit.txt b/Documentation/git-commit.txt
index 51c63d6676..7f34a5b331 100644
--- a/Documentation/git-commit.txt
+++ b/Documentation/git-commit.txt
@@ -314,7 +314,9 @@ changes to tracked files.
 
 -S[<keyid>]::
 --gpg-sign[=<keyid>]::
-	GPG-sign commit.
+	GPG-sign commits. The `keyid` argument is optional and
+	defaults to the committer identity; if specified, it must be
+	stuck to the option without a space.
 
 --no-gpg-sign::
 	Countermand `commit.gpgSign` configuration variable that is
diff --git a/Documentation/git-grep.txt b/Documentation/git-grep.txt
index 1c07c7fe9a..4a44d6da13 100644
--- a/Documentation/git-grep.txt
+++ b/Documentation/git-grep.txt
@@ -165,7 +165,10 @@ OPTIONS
 	Open the matching files in the pager (not the output of 'grep').
 	If the pager happens to be "less" or "vi", and the user
 	specified only one pattern, the first file is positioned at
-	the first match automatically.
+	the first match automatically. The `pager` argument is
+	optional; if specified, it must be stuck to the option
+	without a space. If `pager` is unspecified, the default pager
+	will be used (see `core.pager` in linkgit:git-config[1]).
 
 -z::
 --null::
diff --git a/Documentation/git-merge.txt b/Documentation/git-merge.txt
index 61d43a712d..c06c4f2fb0 100644
--- a/Documentation/git-merge.txt
+++ b/Documentation/git-merge.txt
@@ -67,7 +67,9 @@ include::merge-options.txt[]
 
 -S[<keyid>]::
 --gpg-sign[=<keyid>]::
-	GPG-sign the resulting merge commit.
+	GPG-sign the resulting merge commit. The `keyid` argument is
+	optional and defaults to the committer identity; if specified,
+	it must be stuck to the option without a space.
 
 -m <msg>::
 	Set the commit message to be used for the merge commit (in
diff --git a/Documentation/git-rebase.txt b/Documentation/git-rebase.txt
index 1d01baa5fc..6d72945814 100644
--- a/Documentation/git-rebase.txt
+++ b/Documentation/git-rebase.txt
@@ -285,7 +285,9 @@ which makes little sense.
 
 -S[<keyid>]::
 --gpg-sign[=<keyid>]::
-	GPG-sign commits.
+	GPG-sign commits. The `keyid` argument is optional and
+	defaults to the committer identity; if specified, it must be
+	stuck to the option without a space.
 
 -q::
 --quiet::
diff --git a/Documentation/git-revert.txt b/Documentation/git-revert.txt
index 9eb83f01a4..b15139ffdc 100644
--- a/Documentation/git-revert.txt
+++ b/Documentation/git-revert.txt
@@ -82,7 +82,9 @@ effect to your index in a row.
 
 -S[<keyid>]::
 --gpg-sign[=<keyid>]::
-	GPG-sign commits.
+	GPG-sign commits. The `keyid` argument is optional and
+	defaults to the committer identity; if specified, it must be
+	stuck to the option without a space.
 
 -s::
 --signoff::
diff --git a/Documentation/git-status.txt b/Documentation/git-status.txt
index 335f312335..e1e8f57cdd 100644
--- a/Documentation/git-status.txt
+++ b/Documentation/git-status.txt
@@ -53,8 +53,9 @@ OPTIONS
 --untracked-files[=<mode>]::
 	Show untracked files.
 +
-The mode parameter is optional (defaults to 'all'), and is used to
-specify the handling of untracked files.
+The mode parameter is used to specify the handling of untracked files.
+It is optional: it defaults to 'all', and if specified, it must be
+stuck to the option (e.g. `-uno`, but not `-u no`).
 +
 The possible options are:
 +