Trying to improve documentation on behavior of xlsx subcommand

README.md

@@ -562,21 +562,23 @@ If the length of a cell exceeds `--max-width` it will be truncated with an ellip
 
 ### xlsx
 
-Convert sheets of a XLSX file to CSV.
+Convert sheets of an XLSX file to CSVs.
+
+The command defaults to writing all converted sheets to a directory with the same name as the XLSX file (without the ".xlsx" extension).
 
 Usage:
 
-```shell
-gocsv xlsx [--list-sheets] [--dirname DIRNAME] [--sheet SHEET] FILE
+```none
+gocsv xlsx [--list-sheets | --dirname DIRNAME | --sheet SHEET] FILE
 ```
 
 Arguments:
 
-- `--list-sheets` (optional) List the sheets in the XLSX file.
-- `--sheet` (optional) Specify the sheet (by index or name) of the sheet to convert.
-- `--dirname` (optional) Name of directory to output CSV conversions of sheets from `FILE`. If this is not specified, the command will output the CSV files to a directory with the same name as `FILE` (without the `.xlsx` extension).
+- `--list-sheets` (optional) List the sheets, by index and name, in the XLSX file.
+- `--sheet` (optional) Specify a single sheet, by index or name, to convert and write to stdout.
+- `--dirname` (optional) Specify the name of the directory for the converted sheets.  The command defaults to the same name as `FILE`, minus the extension.
 
-By default the `xlsx` subcommand will convert all the sheets in `FILE` to CSVs to a directory with the same name as `FILE`.
+Only one option can be used; multiple options cannot be combined.
 
 ### zip
 

cmd/xlsx.go

@@ -26,19 +26,37 @@ func (sub *XlsxSubcommand) Description() string {
 	return "Convert sheets of a XLSX file to CSV."
 }
 func (sub *XlsxSubcommand) SetFlags(fs *flag.FlagSet) {
-	fs.BoolVar(&sub.listSheets, "list-sheets", false, "List sheets in file")
-	fs.StringVar(&sub.dirname, "dirname", "", "Name of folder to output sheets to")
-	fs.StringVar(&sub.sheet, "sheet", "", "Name of sheet to convert")
+	fs.BoolVar(&sub.listSheets, "list-sheets", false, "List sheets in file by index and name")
+	fs.StringVar(&sub.dirname, "dirname", "", "Name of folder to write converted sheets to (defaults to file name minus \".xlsx\" extension)")
+	fs.StringVar(&sub.sheet, "sheet", "", "Index or name of sheet to write to stdout")
 }
 
 func (sub *XlsxSubcommand) Run(args []string) {
+	// Check args
 	if len(args) > 1 {
 		fmt.Fprintln(os.Stderr, "Can only convert one file")
 		os.Exit(1)
 	} else if len(args) < 1 {
 		fmt.Fprintln(os.Stderr, "Cannot convert file from stdin")
 		os.Exit(1)
 	}
+	// Check flags
+	flags := []string{}
+	if sub.listSheets {
+		flags = append(flags, "list-sheets")
+	}
+	if sub.dirname != "" {
+		flags = append(flags, "dirname")
+	}
+	if sub.sheet != "" {
+		flags = append(flags, "sheet")
+	}
+	if len(flags) > 1 {
+		fmt.Fprintf(os.Stderr, "Cannot combine flags %s\n", strings.Join(flags, ", "))
+		os.Exit(1)
+	}
+
+	// Run
 	filename := args[0]
 	if sub.listSheets {
 		ListXlxsSheets(filename)