Add -a flag (for autofix)

README.md

@@ -29,19 +29,40 @@ See the [#Docker](#Docker) section for instructions on Docker usage.
 
 > This is a project in development. Use it at your own risk!
 
-Run it and pass a list of file or directories as argument:
+Run it and pass a list of file or directories as argument.
 
 ```console
-linelint .
+$ linelint .
+[EOF Rule] File "LICENSE" has lint errors
+[EOF Rule] Ignoring file "README.md": in rule ignore path
+[EOF Rule] File "linter/eof.go" has lint errors
+
+Total of 2 lint errors!
 ```
 
 Or:
 
 ```console
-linelint README.md LICENSE linter/config.go
+$ linelint README.md LICENSE linter/config.go
+[EOF Rule] File "LICENSE" has lint errors
+
+Total of 1 lint errors!
+```
+
+In case any rule fails, Linelint will fail with an error (exit code 1).
+
+If the `autofix` option is set to `true` (it is `false` by default, activate it with the `-a` flag), it will attempt to fix any file with error.
+
+```console
+$ linelint -a .
+[EOF Rule] File "LICENSE" has lint errors
+[EOF Rule] File "LICENSE" lint errors fixed
+[EOF Rule] Ignoring file "README.md": in rule ignore path
+[EOF Rule] File "linter/eof.go" has lint errors
+[EOF Rule] File "linter/eof.go" lint errors fixed
 ```
 
-In case any rule fails, it will end with an error (exit code 1). If the `autofix` option is set to `true` (it is `false` by default), it will attempt to fix any file with error. If all files are fixed, the program will terminate successfully.
+When all files are fixed successfully, Linelint terminates with with a success as well (exit code 0).
 
 ## Configuration
 

linelint.go

@@ -2,6 +2,7 @@ package main
 
 import (
 	"bufio"
+	"flag"
 	"fmt"
 	"io/ioutil"
 	"os"
@@ -10,16 +11,35 @@ import (
 	"github.com/fernandrone/linelint/linter"
 )
 
+const helpMsg = `usage of %s [-a] [FILE_OR_DIR [FILE_OR_DIR ...]]
+
+Validates simple newline and whitespace rules in all sorts of files.
+
+positional arguments:
+  FILE_OR_DIR		files to format
+
+optional arguments:
+`
+
 func main() {
+	var flagAutofix bool
+	flag.BoolVar(&flagAutofix, "a", false, "(autofix) will automatically fix files with errors in place")
+	flag.Usage = func() {
+		fmt.Fprintf(os.Stderr, helpMsg, os.Args[0])
+		flag.PrintDefaults()
+	}
+	flag.Parse()
+
 	var args, paths []string
 
-	if len(os.Args[1:]) == 0 {
+	if flag.NArg() == 0 {
 		args = []string{"."}
 	} else {
-		args = os.Args[1:]
+		args = flag.Args()
 	}
 
 	config := linter.NewConfig()
+	config.AutoFix = flagAutofix
 
 	// get paths to ignore
 	ignore := linter.MustCompileIgnoreLines(config.Ignore...)