diff --git a/README.md b/README.md
index 25db72a..0ba7e6f 100644
--- a/README.md
+++ b/README.md
@@ -1,2 +1,43 @@
 # acp
-An Advanced Copy Tools, with Process Bar, Sorted Copy Order, MMap Reader and Job Report
+An Advanced Copy Tools, with following extra features:
+- Process bar
+- Sorted copy order, to improve tape device read performance
+- Multi target path, read once write many
+- Read file with mmap, with small file prefetch hint
+- JSON format job report
+- Can use as a golang library
+
+# Install
+```
+# Install acp
+go install github.com/abc950309/acp/cmd/acp
+```
+
+# Usage
+
+```
+Usage of acp:
+  -n    do not overwrite exist file
+  -notarget
+        do not have target, use as dir index tool
+  -report string
+        json report storage path
+  -target value
+        use target flag to give multi target path
+```
+
+## Example
+
+```
+# copy `example` dir to `target` dir
+acp example target/
+
+# copy `example` dir to `target` dir, and output a report to `report.json`
+acp -report report.json example target/
+
+# copy `example` dir to `target1` and `target2` dir
+acp example -target target1 -target target2
+
+# do not copy, just get a dir index, write to `report.json`
+acp example -notarget -report report.json
+```
diff --git a/cmd/main.go b/cmd/acp/main.go
similarity index 98%
rename from cmd/main.go
rename to cmd/acp/main.go
index 94848a5..29b8f3c 100644
--- a/cmd/main.go
+++ b/cmd/acp/main.go
@@ -13,7 +13,7 @@ import (
 
 var (
 	notOverwrite = flag.Bool("n", false, "not overwrite exist file")
-	noTarget     = flag.Bool("notarget", false, "do not have target, aka sha256")
+	noTarget     = flag.Bool("notarget", false, "do not have target, use as dir index tool")
 	reportPath   = flag.String("report", "", "json report storage path")
 	targetPaths  []string
 )