Add version fn to print release version to stdout

README.md

@@ -180,6 +180,9 @@ Date       Description             Accounts
   - **note** - prior to importing your `csv` file into the tool, you must rename the columns in the first line of the `csv` file in the following schema:
     `"date","transaction","name","memo","amount"`.
 
+- version
+  - prints release version to `stdout`.
+
 ### rust_ledger `yaml` file format
 
 - example ledger `yaml` file can be found at `examples/example.yaml`

src/cli.rs

@@ -2,6 +2,7 @@ mod account;
 mod balance;
 mod csv;
 mod register;
+mod version;
 
 use crate::error::{Error, Result};
 use crate::model::ledger::Group;
@@ -17,6 +18,7 @@ pub fn run() -> Result<()> {
         String::from("balance"),
         String::from("register"),
         String::from("csv"),
+        String::from("version"),
     ];
     let expected_flag_args: Vec<String> = vec![];
     let expected_option_args: Vec<String> = vec![
@@ -73,6 +75,7 @@ pub fn run() -> Result<()> {
             "balance" => balance::balance(ledger_file),
             "register" => register::register(ledger_file, &options_arg, group_arg),
             "csv" => csv::csv(ledger_file, &options_arg, &offset_arg),
+            "version" => version::version(),
             _ => panic!("command not found."),
         },
     }

src/cli/version.rs

@@ -0,0 +1,13 @@
+use crate::error::Result;
+
+/// returns package version
+pub fn version() -> Result<()> {
+    let cargo_pkg_version = option_env!("CARGO_PKG_VERSION");
+
+    match cargo_pkg_version {
+        Some(v) => println!("rust_ledger {:?}", v),
+        None => println!("version not found in Cargo.toml"),
+    }
+
+    Ok(())
+}