my .gitconfig file

.gitconfig

[user]
    name = Sheng Yun
    email = uewing@gmail.com
[core]
    excludesfile = /Users/shengy/.gitignore_global
    autocrlf = false
    ; editor = mvim -f
    editor = vi
    ; editor = emacs
[diff]
    ; tool = p4merge
    tool = bcomp
    ; tool = kdiff3
    ; tool = diffmerge
    ; tool = meld
[merge]
    ; tool = p4merge
    tool = bcomp
    ; tool = kdiff3
    ; tool = diffmerge
    ; tool = meld

[difftool "bcomp"]
    trustExitCode = true
    cmd = "/usr/local/bin/bcomp" "$LOCAL" "$REMOTE"
[mergetool "bcomp"]
    trustExitCode = true
    cmd = "/usr/local/bin/bcomp" "$LOCAL" "$REMOTE" "$BASE" "$MERGED"
[difftool "sourcetree"]
    cmd = /Users/shengy/repos/kdiff3-code/kdiff3/releaseQt/kdiff3.app/Contents/MacOS/kdiff3 \"$LOCAL\" \"$REMOTE\"
    path =
[mergetool "sourcetree"]
    cmd = /Users/shengy/repos/kdiff3-code/kdiff3/releaseQt/kdiff3.app/Contents/MacOS/kdiff3 \"$BASE\" \"$LOCAL\" \"$REMOTE\" -o \"$MERGED\"
    trustExitCode = true
[difftool "p4merge"]
    cmd = /Applications/p4merge.app/Contents/MacOS/p4merge \"$LOCAL\" \"$REMOTE\"
[mergetool "p4merge"]
    cmd = /Applications/p4merge.app/Contents/MacOS/p4merge \"$BASE\" \"$LOCAL\" \"$REMOTE\" \"$MERGED\"
    trustExitCode = false
[difftool "diffmerge"]
    cmd = diffmerge \"$LOCAL\" \"$REMOTE\"
[mergetool "diffmerge"]
    cmd = "diffmerge --merge --result=\"$MERGED\" \"$LOCAL\" \"$(if test -f \"$BASE\"; then echo \"$BASE\"; else echo \"$LOCAL\"; fi)\" \"$REMOTE\""
    ; cmd = "diffmerge --merge --result=\"$MERGED\" \"$LOCAL\" \"$BASE\" \"$REMOTE\""
    trustExitCode = true
[alias]
    lg = log --color --graph --pretty=format:'%Cred%h%Creset -%C(yellow)%d%Creset %s %Cgreen(%cr) %C(bold blue)<%an>%Creset' --abbrev-commit
    st = status
    co = checkout
    sb = submodule
    ci = commit
    df = diff
    dt = difftool
[push]
    default = simple
[rerere]
    enabled = false