export a file from a different git branch

Question

Is there a simple way to export a single file from different git branch (local or remote) without checking out that branch?

Answer 1

You can do the following:

 git show experiment:docs/README.txt > /tmp/exported-README.txt

... for a local branch experiment. For a branch that's in the repository you're referring to with the remote origin, you can do the following, similarly:

 git fetch origin
 git show origin/other-experiment:docs/README.txt > /tmp/exported-README-remote.txt

Answer 2

Yup

git show remote/branchname:path/to/file

If you want to save it directly, this might come in handy:

git_showfile () 
{ 
    if [ $# -lt 1 ]; then
        return 255;
    fi;
    local fspec="$1";
    shift;
    local fname="$(basename "$fspec")";
    local fpath="$(dirname "$fspec")";
    local revision=HEAD;
    if [ $# -ge 1 ]; then
        revision="$1";
    fi;
    if [ -e "$fspec" ]; then
        echo not overwriting existing file;
    else
        mkdir -pv "$fpath" && git show "$revision:$fspec" > "$fspec";
    fi
}

Edit: ... which you would use as follows

git_showfile path/to/file 

or

git_showfile path/to/file 237f723edcb89

etc.