diff --git a/rups/Cargo.toml b/rups/Cargo.toml
index 8d729ee..d61cd6c 100644
--- a/rups/Cargo.toml
+++ b/rups/Cargo.toml
@@ -26,6 +26,7 @@ default = []
 ssl = ["rustls", "rustls/dangerous_configuration", "webpki", "webpki-roots"]
 async = ["tokio"]
 async-ssl = ["async", "tokio-rustls", "ssl"]
+write = []
 # a feature gate for examples
 async-rt = ["async", "tokio/rt-multi-thread", "tokio/macros"]
 
diff --git a/rups/src/cmd.rs b/rups/src/cmd.rs
index c31a024..f222ac4 100644
--- a/rups/src/cmd.rs
+++ b/rups/src/cmd.rs
@@ -18,6 +18,9 @@ pub enum Command<'a> {
     NetworkVersion,
     /// Queries the server version.
     Version,
+    #[cfg(feature = "write")]
+    /// Run a command. Allow for on additional optional param.
+    Run(&'a str, Option<&'a str>),
     /// Gracefully shuts down the connection.
     Logout,
 }
@@ -33,6 +36,8 @@ impl<'a> Command<'a> {
             Self::StartTLS => "STARTTLS",
             Self::NetworkVersion => "NETVER",
             Self::Version => "VER",
+            #[cfg(feature = "write")]
+            Self::Run(_, _) => "INSTCMD",
             Self::Logout => "LOGOUT",
         }
     }
@@ -44,6 +49,10 @@ impl<'a> Command<'a> {
             Self::SetUsername(username) => vec![username],
             Self::SetPassword(password) => vec![password],
             Self::List(query) => query.to_vec(),
+            #[cfg(feature = "write")]
+            Self::Run(cmd, param) => param
+                .map(|param| vec![*cmd, param])
+                .unwrap_or_else(|| vec![cmd]),
             _ => Vec::new(),
         }
     }
@@ -826,7 +835,7 @@ implement_simple_commands! {
     pub fn get_network_version() -> String {
         (
             { Command::NetworkVersion },
-            { |row: String| Ok(row) },
+            { Ok },
         )
     }
 
@@ -834,7 +843,7 @@ implement_simple_commands! {
     pub fn get_server_version() -> String {
         (
             { Command::Version },
-            { |row: String| Ok(row) },
+            { Ok },
         )
     }
 }
@@ -855,3 +864,31 @@ implement_action_commands! {
         Command::Logout
     }
 }
+
+#[cfg(feature = "write")]
+impl crate::blocking::Connection {
+    /// Runs a command on the UPS.
+    pub fn run_command(&mut self, cmd: &str, param: Option<&str>) -> crate::Result<()> {
+        match self {
+            Self::Tcp(conn) => {
+                conn.write_cmd(Command::Run(cmd, param))?;
+                conn.read_response()?.expect_ok()?;
+                Ok(())
+            }
+        }
+    }
+}
+
+#[cfg(all(feature = "write", feature = "async"))]
+impl crate::tokio::Connection {
+    /// Runs a command on the UPS.
+    pub async fn run_command(&mut self, cmd: &str, param: Option<&str>) -> crate::Result<()> {
+        match self {
+            Self::Tcp(conn) => {
+                conn.write_cmd(Command::Run(cmd, param)).await?;
+                conn.read_response().await?.expect_ok()?;
+                Ok(())
+            }
+        }
+    }
+}
diff --git a/rups/src/proto/mod.rs b/rups/src/proto/mod.rs
index a1d5c6e..89d6a58 100644
--- a/rups/src/proto/mod.rs
+++ b/rups/src/proto/mod.rs
@@ -213,6 +213,9 @@ macro_rules! impl_sentences {
 /// 2. the decoded sentence
 ///
 /// ```
+/// # #[macro_use] extern crate rups;
+/// # fn main() {
+/// # #[cfg(test)]
 ///  test_encode_decode!(
 ///      ["GET", "VAR", "nutdev", "test.var"] <=>
 ///      Sentences::QueryVar {
@@ -220,6 +223,7 @@ macro_rules! impl_sentences {
 ///          var_name: "test.var".into(),
 ///      }
 ///  );
+/// # }
 /// ```
 #[allow(unused_macros)]
 macro_rules! test_encode_decode {
diff --git a/rups/src/var.rs b/rups/src/var.rs
index 84e0a24..cdfea10 100644
--- a/rups/src/var.rs
+++ b/rups/src/var.rs
@@ -5,7 +5,7 @@ use std::time::Duration;
 
 /// Well-known variable keys for NUT UPS devices.
 ///
-/// List retrieved from: https://networkupstools.org/docs/user-manual.chunked/apcs01.html
+/// List retrieved from: <https://networkupstools.org/docs/user-manual.chunked/apcs01.html>
 pub mod key {
     /// Device model.
     pub const DEVICE_MODEL: &str = "device.model";
@@ -31,7 +31,7 @@ pub mod key {
 
 /// Well-known variables for NUT UPS devices.
 ///
-/// List retrieved from: https://networkupstools.org/docs/user-manual.chunked/apcs01.html
+/// List retrieved from: <https://networkupstools.org/docs/user-manual.chunked/apcs01.html>
 #[derive(Debug, Clone, Eq, PartialEq)]
 pub enum Variable {
     /// Device model.
@@ -196,10 +196,8 @@ impl TryFrom<&str> for VariableType {
             other => {
                 if other.starts_with("STRING:") {
                     let size = other
-                        .splitn(2, ':')
-                        .nth(1)
-                        .map(|s| s.parse().ok())
-                        .flatten()
+                        .split_once(':')
+                        .and_then(|(_, s)| s.parse().ok())
                         .ok_or_else(|| crate::ClientError::generic("Invalid STRING definition"))?;
                     Ok(Self::String(size))
                 } else {