another (unsuccessful) stab at making ediff.sh work

bin/ediff.sh

@@ -1,18 +1,55 @@
 #!/bin/bash
 
-if [[ -z $2 ]]; then
-    echo "USAGE: ediff <FILE 1> <FILE 2>"
+# modified from http://ulf.zeitform.de/en/documents/git-ediff.html
+
+# test args
+if [ ! ${#} -ge 3 ]; then
+    echo 1>&2 "Usage: ${0} LOCAL REMOTE MERGED BASE"
+    echo 1>&2 "       (LOCAL, REMOTE, MERGED, BASE can be provided by \`git mergetool'.)"
     exit 1
 fi
 
+# tools
 if [[ $(uname) == 'Darwin' ]]; then
     EMACS=/Applications/Emacs.app/Contents/MacOS/Emacs
+    _EGREP=/usr/bin/egrep
+    _MKTEMP=/usr/bin/mktemp
+else
+    _EMACS=emacs
+    _EGREP=/bin/egrep
+    _MKTEMP=/bin/mktemp
+fi
+
+_BASENAME=/usr/bin/basename
+_CP=/bin/cp
+
+# args
+_LOCAL=${1}
+_REMOTE=${2}
+_MERGED=${3}
+if [ ${4} -a -r ${4} ] ; then
+    _BASE=${4}
+    _EDIFF=ediff-merge-files-with-ancestor
+    _EVAL="${_EDIFF} \"${_LOCAL}\" \"${_REMOTE}\" \"${_BASE}\" nil \"${_MERGED}\""
+elif [ ${_REMOTE} = ${_MERGED} ] ; then
+    _EDIFF=ediff
+    _EVAL="${_EDIFF} \"${_LOCAL}\" \"${_REMOTE}\""
 else
-    EMACS=emacs
+    _EDIFF=ediff-merge-files
+    _EVAL="${_EDIFF} \"${_LOCAL}\" \"${_REMOTE}\" nil \"${_MERGED}\""
 fi
 
-TERM=xterm-256color ${EMACS:?} -nw -q \
-    --eval "(setq ediff-split-window-function 'split-window-horizontally)" \
-    --eval "(ediff-files \"$1\" \"$2\")"
+# run emacsclient
+${_EMACS} -nw -q --eval "(${_EVAL})" 2>&1
+
+# check modified file
+if [ ! $(egrep -c '^(<<<<<<<|=======|>>>>>>>|####### Ancestor)' ${_MERGED}) = 0 ]; then
+    _MERGEDSAVE=$(${_MKTEMP} --tmpdir `${_BASENAME} ${_MERGED}`.XXXXXXXXXX)
+    ${_CP} ${_MERGED} ${_MERGEDSAVE}
+    echo 1>&2 "Oops! Conflict markers detected in $_MERGED."
+    echo 1>&2 "Saved your changes to ${_MERGEDSAVE}"
+    echo 1>&2 "Exiting with code 1."
+    exit 1
+fi
 
-rm -f $script
+exit 0