diff --git a/src/cmd_sync.rs b/src/cmd_sync.rs
index 2c2a213..c462c87 100644
--- a/src/cmd_sync.rs
+++ b/src/cmd_sync.rs
@@ -1,7 +1,10 @@
-use std::path::{Path, PathBuf};
+use std::{
+    io::{self, Write},
+    path::{Path, PathBuf},
+};
 
-use anyhow::{anyhow, Result};
-use git2::{Cred, PushOptions, RemoteCallbacks, Repository};
+use anyhow::{anyhow, Context, Result};
+use git2::{build::CheckoutBuilder, Cred, FetchOptions, PushOptions, RemoteCallbacks, Repository};
 
 pub(crate) fn cmd_sync(
     config_dir: &PathBuf,
@@ -21,12 +24,154 @@ pub(crate) fn cmd_sync(
             remotes.get(0).unwrap().to_string()
         }
     };
+    debug!("remote name: {remote_name}");
 
+    let mut remote = repo.find_remote(&remote_name)?;
+    let callbacks = remote_callback(&use_sshagent, &ssh_key);
+    let mut fetchoptions = FetchOptions::new();
+    fetchoptions.remote_callbacks(callbacks);
+    let fetch_refspec: Vec<String> = remote
+        .refspecs()
+        .filter_map(|rs| match rs.direction() {
+            git2::Direction::Fetch => rs.str().map(|s| s.to_string()),
+            git2::Direction::Push => None,
+        })
+        .collect();
+    remote
+        .fetch(&fetch_refspec, Some(&mut fetchoptions), None)
+        .context("Failed to fetch (pull)")?;
+    let stats = remote.stats();
+    if stats.local_objects() > 0 {
+        println!(
+            "\rReceived {}/{} objects in {} bytes (used {} local objects)",
+            stats.indexed_objects(),
+            stats.total_objects(),
+            stats.received_bytes(),
+            stats.local_objects(),
+        );
+    } else {
+        println!(
+            "\rReceived {}/{} objects in {} bytes",
+            stats.indexed_objects(),
+            stats.total_objects(),
+            stats.received_bytes(),
+        );
+    }
+    let fetch_head = repo
+        .reference_to_annotated_commit(
+            &repo
+                .resolve_reference_from_short_name(&remote_name)
+                .context("failed to get reference from fetch refspec")?,
+        )
+        .context("failed to get annotated commit")?;
+    let (merge_analysis, merge_preference) = repo
+        .merge_analysis(&[&fetch_head])
+        .context("failed to do merge_analysis")?;
+
+    trace!("merge analysis: {:?}", merge_analysis);
+    trace!("merge preference: {:?}", merge_preference);
+    match merge_analysis {
+        ma if ma.is_up_to_date() => {
+            info!("HEAD is up to date. skip merging");
+        }
+        ma if ma.is_fast_forward() => {
+            // https://github.com/rust-lang/git2-rs/blob/master/examples/pull.rs
+            info!("fast forward is available");
+            let mut ref_remote = repo
+                .find_reference(
+                    remote
+                        .default_branch()
+                        .context("failed to get remote default branch")?
+                        .as_str()
+                        .unwrap(),
+                )
+                .context("failed to get remote reference")?;
+            let name = match ref_remote.name() {
+                Some(s) => s.to_string(),
+                None => String::from_utf8_lossy(ref_remote.name_bytes()).to_string(),
+            };
+            let msg = format!("Fast-Forward: Setting {} to id: {}", name, fetch_head.id());
+            println!("{}", msg);
+            ref_remote
+                .set_target(fetch_head.id(), &msg)
+                .context("failed to set target")?;
+            repo.checkout_head(Some(CheckoutBuilder::default().force()))
+                .context("failed to checkout")?;
+        }
+        ma if ma.is_unborn() => {
+            warn!("HEAD is invalid (unborn)");
+            return Err(anyhow!(
+                "HEAD is invalid: merge_analysis: {:?}",
+                merge_analysis
+            ));
+        }
+        ma if ma.is_normal() => {
+            error!("unable to fast-forward. manual merge is required");
+            return Err(anyhow!("unable to fast-forward. manual merge is required"));
+        }
+        ma if ma.is_none() => {
+            error!("no merge is possible");
+            return Err(anyhow!("no merge is possible"));
+        }
+        _ma => {
+            error!(
+                "this code must not reachable: merge_analysis {:?}",
+                merge_analysis
+            );
+            return Err(anyhow!("must not be reachabel (uncovered merge_analysis)"));
+        }
+    }
+
+    // push
+    let callbacks = remote_callback(&use_sshagent, &ssh_key);
+    let mut push_options = PushOptions::new();
+    push_options.remote_callbacks(callbacks);
+    trace!("remote: {:?}", remote.name());
+    let num_refspecs = remote
+        .refspecs()
+        .filter(|rs| rs.direction() == git2::Direction::Push)
+        .count();
+    if num_refspecs > 1 {
+        warn!("more than one push refspecs are configured");
+        warn!("using the first one");
+    }
+    let head = repo.head().context("Failed to get HEAD")?;
+    if num_refspecs >= 1 {
+        trace!("using push refspec");
+        let push_refspec = remote
+            .refspecs()
+            .filter_map(|rs| match rs.direction() {
+                git2::Direction::Fetch => None,
+                git2::Direction::Push => Some(rs),
+            })
+            .next()
+            .expect("this must be unreachabe")
+            .str()
+            .context("failed to get valid utf8 push refspec")?
+            .to_string();
+        remote.push(&[push_refspec.as_str()] as &[&str], Some(&mut push_options))?;
+    } else {
+        trace!("using head as push refspec");
+        trace!("head is branch: {:?}", head.is_branch());
+        trace!("head is remote: {:?}", head.is_remote());
+        let push_refspec = head.name().context("failed to get head name")?;
+        remote.push(&[push_refspec] as &[&str], Some(&mut push_options))?;
+    };
+    Ok(())
+}
+
+fn remote_callback<'b, 'a>(
+    use_sshagent: &'a bool,
+    ssh_key: &'b Option<PathBuf>,
+) -> RemoteCallbacks<'a>
+where
+    'b: 'a,
+{
     // using credentials
     let mut callbacks = RemoteCallbacks::new();
     callbacks
-        .credentials(|_url, username_from_url, _allowed_types| {
-            if let Some(key) = &ssh_key {
+        .credentials(move |_url, username_from_url, _allowed_types| {
+            if let Some(ref key) = ssh_key {
                 info!("Using provided ssh key to access the repository");
                 let passwd = match inquire::Password::new("SSH passphrase").prompt() {
                     std::result::Result::Ok(s) => Some(s),
@@ -42,7 +187,7 @@ pub(crate) fn cmd_sync(
                     key as &Path,
                     passwd.as_deref(),
                 )
-            } else if use_sshagent {
+            } else if *use_sshagent {
                 // use ssh agent
                 info!("Using ssh agent to access the repository");
                 Cred::ssh_key_from_agent(
@@ -54,41 +199,49 @@ pub(crate) fn cmd_sync(
                 panic!("This option must be unreachable.")
             }
         })
+        .transfer_progress(|progress| {
+            if progress.received_objects() == progress.total_objects() {
+                print!(
+                    "Resolving deltas {}/{}\r",
+                    progress.indexed_deltas(),
+                    progress.total_deltas()
+                );
+            } else {
+                print!(
+                    "Received {}/{} objects ({}) in {} bytes\r",
+                    progress.received_objects(),
+                    progress.total_objects(),
+                    progress.indexed_objects(),
+                    progress.received_bytes(),
+                );
+            }
+            io::stdout().flush().unwrap();
+            true
+        })
+        .sideband_progress(|text| {
+            let msg = String::from_utf8_lossy(text);
+            eprintln!("remote: {msg}");
+            true
+        })
         .push_transfer_progress(|current, total, bytes| {
-            trace!("{current},\t{total},\t{bytes}");
+            trace!("{current}/{total} files sent \t{bytes} bytes");
+        })
+        .push_update_reference(|reference_name, status_msg| {
+            debug!("remote reference_name {reference_name}");
+            match status_msg {
+                None => {
+                    info!("successfully pushed");
+                    eprintln!("successfully pushed to {}", reference_name);
+                    Ok(())
+                }
+                Some(status) => {
+                    error!("failed to push: {}", status);
+                    Err(git2::Error::from_str(&format!(
+                        "failed to push to {}: {}",
+                        reference_name, status
+                    )))
+                }
+            }
         });
-    callbacks.push_update_reference(|reference_name, status_msg| {
-        debug!("remote reference_name {reference_name}");
-        match status_msg {
-            None => {
-                info!("successfully pushed");
-                eprintln!("successfully pushed to {}", reference_name);
-                Ok(())
-            }
-            Some(status) => {
-                error!("failed to push: {}", status);
-                Err(git2::Error::from_str(&format!(
-                    "failed to push to {}: {}",
-                    reference_name, status
-                )))
-            }
-        }
-    });
-    let mut push_options = PushOptions::new();
-    push_options.remote_callbacks(callbacks);
-    let mut remote = repo.find_remote(&remote_name)?;
-    trace!("remote: {:?}", remote.name());
-    if remote.refspecs().len() != 1 {
-        warn!("multiple refspecs found");
-    }
-    trace!("refspec: {:?}", remote.get_refspec(0).unwrap().str());
-    trace!("refspec: {:?}", remote.get_refspec(0).unwrap().direction());
-    trace!("refspec: {:?}", repo.head().unwrap().name());
-    trace!("head is branch: {:?}", repo.head().unwrap().is_branch());
-    trace!("head is remote: {:?}", repo.head().unwrap().is_remote());
-    remote.push(
-        &[repo.head().unwrap().name().unwrap()] as &[&str],
-        Some(&mut push_options),
-    )?;
-    Ok(())
+    callbacks
 }