This allows you to do git cp sha1:path destination

git-cp.sh

#!/bin/bash
# To use do something like add this to your .gitconfig
# [alias]
#   cp = "!$HOME/.local/bin/git-cp.sh"
#
# Then you can do things like
#   $  git cp sha1:/path/to/old/file /tmp

set -e

usage() {
    echo "Usage: git-cp.sh <sha1>:/path/to/file [destination]"
    echo ""
    echo "Copy a file from a specific commit to your current working directory"
    echo "or to a specified destination."
    echo ""
    echo "Arguments:"
    echo "  <sha1>:/path/to/file   Source file reference (commit SHA1 and file path)"
    echo "  [destination]          Optional destination (file or directory)"
    exit 1
}

# Check if at least one argument is provided
if [ $# -lt 1 ]; then
    usage
fi

# Parse the source argument
source="$1"

# Check if the source follows the expected pattern
if [[ ! "$source" =~ ^([a-f0-9]+):(.*) ]]; then
    echo "Error: Invalid source format. Expected <sha1>:/path/to/file"
    usage
fi

# Extract the commit SHA1 and file path
commit="${BASH_REMATCH[1]}"
source_path="${BASH_REMATCH[2]}"

# Validate that the commit exists
if ! git rev-parse --verify "$commit^{commit}" >/dev/null 2>&1; then
    echo "Error: Commit '$commit' not found"
    exit 1
fi

# Determine the destination
if [ $# -ge 2 ]; then
    destination="$2"
else
    # If no destination is provided, use the basename of the source
    destination=$(basename "$source_path")
fi

# Check if destination is a directory
if [ -d "$destination" ]; then
    # If destination is a directory, append the basename of the source
    destination="${destination%/}/$(basename "$source_path")"
fi

# Extract the file from the specified commit
git show "$commit:$source_path" > "$destination"

echo "File copied successfully"