/usr/lib/fai/get-config-dir-git is in fai-client 4.0.8~deb7u1.
This file is owned by root:root, with mode 0o755.
The actual contents of the file can be viewed below.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61  | #!/bin/bash
# (c) 2002-2006 Henning Glawe <glaweh@debian.org>
# (c) 2007 Holger Levsen <holger@layer-acht.org> for the modifications to use git
# (c) 2011 Michael Goetze <mgoetze@mgoetze.net>
### BEGIN SUBROUTINE INFO
# Provides-Var:    $GIT_WORK_TREE $GIT_DIR
# Requires-Var:    $FAI_CONFIG_SRC $FAI $LOGDIR
# Suggests-Var:
# Short-Description: get $FAI from a git repository.
### END SUBROUTINE INFO
# matched string: "git://gitpath"
protocol=$(expr match "$FAI_CONFIG_SRC" '\([^:]*\)://')
gitpath=$(expr match "$FAI_CONFIG_SRC" '[^:]*://\([^[:space:]#]\+\)')
gitbranch=$(expr match "$FAI_CONFIG_SRC" '[^#]*#\([^[:space:]]\+\)')
[ -n "$gitbranch" ] || gitbranch=master
case $protocol in
        git)
                giturl="git://$gitpath"
                ;;
        git+*)
                giturl="${protocol:4}://$gitpath"
                ;;
        *)
                echo "get-config-dir-git: protocol should be git or start with git+"
                exit 1
                ;;
esac
export GIT_WORK_TREE="$FAI"
export GIT_DIR="$FAI/.git"
_git_checkout() {
    git checkout -f "origin/$gitbranch"
    task_error 882 $?
    git clean -df
    task_error 882 $?
}
if [ -d "$GIT_DIR" ]; then
    if [ `git remote show -n origin | egrep -m1 -o '[^[:space:]]+://.+'` == "$giturl" ]; then
        echo "Updating git copy in $FAI"
        git fetch
        task_error 881 $?
        _git_checkout
    else
        echo "$FAI already contains a git repository, but it is not from $giturl!" >&2
        echo "Please delete $FAI manually. Aborting..." >&2
        task_error 883
    fi
else
   echo "Checking out from git"
   # cloning into an existing directory is not allowed
   [ -d $FAI ] && rm -rf $FAI
   git clone --branch "$gitbranch" "$giturl" $FAI
   task_error 882 $?
    _git_checkout
fi
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