我也遇到过类似的问题，我想让我的~/.gitconfig可以跨平台移植，这样我就可以在Macbook和Linux VM上使用相同的gitconfig。我需要credential.helper根据平台的不同而有所不同。
最后，我编写了一个小的generate_gitconfig脚本，并将其添加到我的bashrc中，以便在启动每个shell会话时自动生成~/.gitconfig。
通过脚本编写gitconfig给了你更多的灵活性，因为你可以根据环境变量、是否安装了某些命令、机器的主机名等来动态设置值。
下面是我的generate_gitconfig脚本，作为一个例子：

#!/bin/bash

cat <<EOF > $HOME/.gitconfig
# This gitconfig was generated via ~/.bin/generate_gitconfig.
# Edit that file, not this one!

[user]
    name = Dave Yarwood
    email = dave.yarwood@gmail.com
[push]
    default = simple
[core]
    autocrlf = input
    editor = nvim
    excludesfile = $HOME/.gitignore_global
[rerere]
    enabled = true
EOF

if [[ "$(uname)" == Darwin ]]; then
  CREDENTIAL_HELPER="osxkeychain"
elif [[ -n "$(which gnome-keyring-daemon)" ]]; then
  CREDENTIAL_HELPER="/usr/share/doc/git/contrib/credential/gnome-keyring/git-credential-gnome-keyring"
fi

if [[ -n "$CREDENTIAL_HELPER" ]]; then
  cat <<EOF >> $HOME/.gitconfig
[credential]
  helper = $CREDENTIAL_HELPER
EOF
fi

EDIT 05-2016As @amynbe comments，git >= 2.5 has git-worktree https://git-scm.com/docs/git-worktree

我有一个脚本，有人在freenode上传递，我不确定作者，但我知道我可以分享，它用于创建基于分支的不同工作副本，我认为它可以适合您的用例：

#!/bin/sh

usage () {
        echo "usage:" $@
        exit 127
}

die () {
        echo $@
        exit 128
}

if test $# -lt 2 || test $# -gt 3
then
        usage "$0 <repository> <new_workdir> [<branch>]"
fi

orig_git=$1
new_workdir=$2
branch=$3

# want to make sure that what is pointed to has a .git directory ...
git_dir=$(cd "$orig_git" 2>/dev/null &&
  git rev-parse --git-dir 2>/dev/null) ||
  die "Not a git repository: \"$orig_git\""

case "$git_dir" in
.git)
        git_dir="$orig_git/.git"
        ;;
.)
        git_dir=$orig_git
        ;;
esac

# don't link to a configured bare repository
isbare=$(git --git-dir="$git_dir" config --bool --get core.bare)
if test ztrue = z$isbare
then
        die "\"$git_dir\" has core.bare set to true," \
                " remove from \"$git_dir/config\" to use $0"
fi

# don't link to a workdir
if test -h "$git_dir/config"
then
        die "\"$orig_git\" is a working directory only, please specify" \
                "a complete repository."
fi

# don't recreate a workdir over an existing repository
if test -e "$new_workdir"
then
        die "destination directory '$new_workdir' already exists."
fi

# make sure the links use full paths
git_dir=$(cd "$git_dir"; pwd)

# create the workdir
mkdir -p "$new_workdir/.git" || die "unable to create \"$new_workdir\"!"

# create the links to the original repo.  explicitly exclude index, HEAD and
# logs/HEAD from the list since they are purely related to the current working
# directory, and should not be shared.
for x in config refs logs/refs objects info hooks packed-refs remotes rr-cache svn
do
        case $x in
        */*)
                mkdir -p "$(dirname "$new_workdir/.git/$x")"
                ;;
        esac
        ln -s "$git_dir/$x" "$new_workdir/.git/$x"
done

# now setup the workdir
cd "$new_workdir"
# copy the HEAD from the original repository as a default branch
cp "$git_dir/HEAD" .git/HEAD
# checkout the branch (either the same as HEAD from the original repository, or
# the one that was asked for)
git checkout -f $branch