How do I clone, fetch or sparse checkout a single directory or a list of directories from git repository?

Question

How do I clone, fetch or sparse checkout a single file or directory or a list of files or directories from a git repository avoiding downloading the entire history or at least keeping history download at minimum?

For the benefit of people landing here, these are references to other similar questions:

• How do I clone a subdirectory only of a Git repository?
• How to sparsely checkout only one single file from a git repository?
• Is it possible to do a sparse checkout without checking out the whole repository first?

These similar questions were asked long ago and git evolved ever since, which ended up causing a flood of different answers, some better, some worse, depending on the version of git being considered. The trouble is that not a single answer from these aforementioned questions attend all requirements from all these questions combined, which means that you have to read all answers and compile in your head your own answer which eventually attend all requirements.

This question here expands on previous questions mentioned, imposing more flexible and stringent requirements than all other questions combined. So, once again:

How do I clone, fetch or sparse checkout a single file or directory or a list of files or directories from a git repository avoiding downloading the entire history or at least keeping history download at minimum?

Answer 1

This bash function below does the trick.

function git_sparse_checkout {
    # git repository, e.g.: http://github.com/frgomes/bash-scripts
    local url=$1
    # directory where the repository will be downloaded, e.g.: ./build/sources
    local dir=$2
    # repository name, in general taken from the url, e.g.: bash-scripts
    local prj=$3
    # tag, e.g.: master
    local tag=$4
    [[ ( -z "$url" ) || ( -z "$dir" ) || ( -z "$prj" ) || ( -z "$tag" ) ]] && \
        echo "ERROR: git_sparse_checkout: invalid arguments" && \
        return 1
    shift; shift; shift; shift

    # Note: any remaining arguments after these above are considered as a
    # list of files or directories to be downloaded.
    
    mkdir -p ${dir}
    if [ ! -d ${dir}/${prj} ] ;then
        mkdir -p ${dir}/${prj}
        pushd ${dir}/${prj}
        git init
        git config core.sparseCheckout true
        local path="" # local scope
        for path in $* ;do
            echo "${path}" >> .git/info/sparse-checkout
        done
        git remote add origin ${url}
        git fetch --depth=1 origin ${tag}
        git checkout ${tag}
        popd
    fi
}

This is an example of how this can be used:

function example_download_scripts {
  url=http://github.com/frgomes/bash-scripts
  dir=$(pwd)/sources
  prj=bash-scripts
  tag=master
  git_sparse_checkout $url $dir $prj $tag "user-install/*" sysadmin-install/install-emacs.sh
}

In the example above, notice that a directory must be followed by /* and must be between single quotes or double quotes.

UPDATE: An improved version can be found at: https://github.com/frgomes/bash-scripts/blob/master/bin/git_sparse_checkout