A zsh function to delete n lines of .zsh_history

delhist.sh

delhist() {
    local num_lines="$1"
    local file="$HOME/.zsh_history"

    if [[ ! "$num_lines" =~ ^[0-9]+$ ]]; then
        echo "Invalid number of lines: $num_lines"
        return 1
    fi

    local total_lines=$(wc -l < "$file")
    local lines_to_keep=$((total_lines - num_lines))

    if [[ "$lines_to_keep" -lt 0 ]]; then
        echo "The file has fewer lines than the specified number."
        return 1
    fi

    head -n "$lines_to_keep" "$file" >! "$file.tmp"
    # copy over the contents so we keep the .tmp file as a back up just in case
    cp -f "$file.tmp" "$file"

    echo "Deleted $num_lines line(s) from '$file'."
}