Teach git var about GIT_EDITOR

Expose the command used by launch_editor() for scripts to use.
This should allow one to avoid searching for a proper editor
separately in each command.

git_editor(void) uses the logic to decide which editor to use
that used to live in launch_editor().  The function returns NULL
if there is no suitable editor; the caller is expected to issue
an error message when appropriate.

launch_editor() uses git_editor() and gives the error message the
same way as before when EDITOR is not set.

"git var GIT_EDITOR" gives the editor name, or an error message
when there is no appropriate one.

"git var -l" gives GIT_EDITOR=name only if there is an
appropriate editor.

Originally-submitted-by: Johannes Sixt <j6t@kdbg.org>
Signed-off-by: Jonathan Nieder <jrnieder@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

1 files changed, 8 insertions, 0 deletions

diff --git a/Documentation/git-var.txt b/Documentation/git-var.txt
index e2f4c09..89e4b4f 100644
--- a/Documentation/git-var.txt
+++ b/Documentation/git-var.txt
@@ -36,6 +36,14 @@ GIT_AUTHOR_IDENT::
 GIT_COMMITTER_IDENT::
     The person who put a piece of code into git.
 
+GIT_EDITOR::
+    Text editor for use by git commands.  The value is meant to be
+    interpreted by the shell when it is used.  Examples: `~/bin/vi`,
+    `$SOME_ENVIRONMENT_VARIABLE`, `"C:\Program Files\Vim\gvim.exe"
+    --nofork`.  The order of preference is the `$GIT_EDITOR`
+    environment variable, then `core.editor` configuration, then
+    `$VISUAL`, then `$EDITOR`, and then finally 'vi'.
+
 Diagnostics
 -----------
 You don't exist. Go away!::