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 0d8ba48..6b09891 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 66ab297..77da29a 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 f5f2a8d..a0b5457 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 51c63d6..7f34a5b 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 1c07c7f..4a44d6d 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 61d43a7..c06c4f2 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 1d01baa..6d72945 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 9eb83f0..b15139f 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 335f312..e1e8f57 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:
 +