Александр Никульшин

public IActionResult Index()
        {
            if (System.IO.File.Exists(@"d:\1_.docx"))
                System.IO.File.Delete(@"d:\1_.docx");
            System.IO.File.Copy(@"d:\1.docx", @"d:\1_.docx");
            using (var doc = WordprocessingDocument.Open(@"d:\1_.docx", true))
            {
                var body = doc.MainDocumentPart.Document.Body;
                var paras = body.Elements<Paragraph>();
                foreach (var para in paras)
                {
                    foreach (var run in para.Elements<Run>())
                    {
                        foreach (var text in run.Elements<Text>())
                        {
                            if (text.Text.Contains("replaced-text"))
                            {
                                text.Text = text.Text.Replace("replaced-text", DateTime.Now.ToString("dd.MM.yy"));
                            }
                        }
                    }
                }
                doc.Save();
                doc.Close();
            }
            string path = @"d:\1_.docx";
            FileStream fs = new FileStream(path, FileMode.Open);
            string file_type = "application/vnd.openxmlformats-officedocument.wordprocessingml.document";
            string file_name = "book3.docx";
            return File(fs, file_type, file_name);
            /*
            using (MemoryStream mem = new MemoryStream())
            {
                using (WordprocessingDocument wordDoc = WordprocessingDocument.Create(mem, DocumentFormat.OpenXml.WordprocessingDocumentType.Document, true))
                {
                    wordDoc.AddMainDocumentPart();
                    // siga a ordem
                    Document doc = new Document();
                    Body body = new Body();
                    // 1 paragrafo
                    Paragraph para = new Paragraph();

                    ParagraphProperties paragraphProperties1 = new ParagraphProperties();
                    ParagraphStyleId paragraphStyleId1 = new ParagraphStyleId() { Val = "Normal" };
                    Justification justification1 = new Justification() { Val = JustificationValues.Center };
                    ParagraphMarkRunProperties paragraphMarkRunProperties1 = new ParagraphMarkRunProperties();

                    paragraphProperties1.Append(paragraphStyleId1);
                    paragraphProperties1.Append(justification1);
                    paragraphProperties1.Append(paragraphMarkRunProperties1);

                    Run run = new Run();
                    RunProperties runProperties1 = new RunProperties();

                    Text text = new Text() { Text = "The OpenXML SDK rocks!" };

                    // siga a ordem 
                    run.Append(runProperties1);
                    run.Append(text);
                    para.Append(paragraphProperties1);
                    para.Append(run);

                    // 2 paragrafo
                    Paragraph para2 = new Paragraph();

                    ParagraphProperties paragraphProperties2 = new ParagraphProperties();
                    ParagraphStyleId paragraphStyleId2 = new ParagraphStyleId() { Val = "Normal" };
                    Justification justification2 = new Justification() { Val = JustificationValues.Start };
                    ParagraphMarkRunProperties paragraphMarkRunProperties2 = new ParagraphMarkRunProperties();

                    paragraphProperties2.Append(paragraphStyleId2);
                    paragraphProperties2.Append(justification2);
                    paragraphProperties2.Append(paragraphMarkRunProperties2);

                    Run run2 = new Run();
                    RunProperties runProperties3 = new RunProperties();
                    Text text2 = new Text();
                    text2.Text = "Teste aqui";

                    run2.AppendChild(new Break());
                    run2.AppendChild(new Text("Hello"));
                    run2.AppendChild(new Break());
                    run2.AppendChild(new Text("world"));

                    para2.Append(paragraphProperties2);
                    para2.Append(run2);

                    // todos os 2 paragrafos no main body
                    body.Append(para);
                    body.Append(para2);

                    doc.Append(body);

                    wordDoc.MainDocumentPart.Document = doc;

                    wordDoc.Close();
                }
                return File(mem.ToArray(), "application/vnd.openxmlformats-officedocument.wordprocessingml.document", "ABC.docx");
            }
            */
        }

int main(string args[])
{
foreach (string s in args)
//какие то действия с переданными параметрами
}