git-skip

#!/bin/sh
set -e

usage () {
    echo "usage: git skip [-ah] <file> [<file> ...]" >&2
    echo >&2
    echo "Skip (ignore) local changes to git-aware files to prevent them from" >&2
    echo "showing up in status reports or diffs, as if they haven't been changed" >&2
    echo "locally at all." >&2
    echo >&2
    echo "To reset, use git-unskip." >&2
    echo >&2
    echo "Options:" >&2
    echo "-a    Skip all locally modified files" >&2
    echo "-h    Show this help" >&2
}

all=0
while getopts ah flag; do
    case "$flag" in
        a) all=1;;
        h) usage; exit 2;;
    esac
done
shift $(($OPTIND - 1))

locally_modified_files () {
    git status --porcelain --untracked-files=no | cut -c 2- | grep -Ee '^[MD]' | cut -c 3-
}

if [ $all -eq 1 ]; then
    git update-index --skip-worktree $(locally_modified_files)
else
    if [ $# -gt 0 ]; then
        git update-index --skip-worktree "$@"
    else
        usage
        exit 2
    fi
fi