diff --git a/src/cmd/mod.rs b/src/cmd/mod.rs
index 36404c4..08b25d7 100644
--- a/src/cmd/mod.rs
+++ b/src/cmd/mod.rs
@@ -33,7 +33,7 @@ mod rm;
 mod rmdir;
 pub mod shitbox;
 pub mod sleep;
-mod sync;
+pub mod sync;
 pub mod r#true;
 pub mod which;
 pub mod whoami;
@@ -43,8 +43,8 @@ pub use {
     self::hostname::Hostname, base32::Base32, base64::Base64, basename::Basename,
     bootstrap::Bootstrap, clear::Clear, dirname::Dirname, echo::Echo, factor::Factor, fold::Fold,
     groups::Groups, head::Head, link::Link, mountpoint::Mountpoint, nologin::Nologin, nproc::Nproc,
-    r#false::False, r#true::True, rev::Rev, shitbox::Shitbox, sleep::Sleep, which::Which,
-    whoami::Whoami, yes::Yes,
+    r#false::False, r#true::True, rev::Rev, shitbox::Shitbox, sleep::Sleep, sync::SYnc,
+    which::Which, whoami::Whoami, yes::Yes,
 };
 
 pub trait Cmd: fmt::Debug + Sync {
@@ -75,6 +75,7 @@ pub fn get(name: &str) -> Option<Box<dyn Cmd>> {
         "rev" => Some(Box::new(Rev::default())),
         "shitbox" => Some(Box::new(Shitbox::default())),
         "sleep" => Some(Box::new(Sleep::default())),
+        "sync" => Some(Box::new(SYnc::default())),
         "true" => Some(Box::new(True::default())),
         "which" => Some(Box::new(Which::default())),
         "whoami" => Some(Box::new(Whoami::default())),
@@ -83,7 +84,7 @@ pub fn get(name: &str) -> Option<Box<dyn Cmd>> {
     }
 }
 
-pub static COMMANDS: [&'static str; 24] = [
+pub static COMMANDS: [&'static str; 25] = [
     "base32",
     "base64",
     "basename",
@@ -104,6 +105,7 @@ pub static COMMANDS: [&'static str; 24] = [
     "rev",
     "sleep",
     "shitbox",
+    "sync",
     "true",
     "which",
     "whoami",
diff --git a/src/cmd/sync/mod.rs b/src/cmd/sync/mod.rs
index 8b13789..86fe70f 100644
--- a/src/cmd/sync/mod.rs
+++ b/src/cmd/sync/mod.rs
@@ -1 +1,77 @@
+use super::Cmd;
+use clap::{Arg, ArgAction, Command};
+use std::{error::Error, io, ffi::CString};
 
+#[derive(Debug, Default)]
+pub struct SYnc;
+
+impl Cmd for SYnc {
+    fn cli(&self) -> clap::Command {
+        Command::new("sync")
+            .about("force completion of pending disk writes (flush cache)")
+            .author("Nathan Fisher")
+            .version(env!("CARGO_PKG_VERSION"))
+            .args([
+                Arg::new("data")
+                    .short('d')
+                    .long("data")
+                    .help("sync only file data, no unneeded metadata")
+                    .conflicts_with("fs")
+                    .action(ArgAction::SetTrue),
+                Arg::new("fs")
+                    .short('f')
+                    .long("file-system")
+                    .help("sync the file systems that contain the files")
+                    .action(ArgAction::SetTrue),
+                Arg::new("FILE")
+                    .help(
+                        "If one or more files are specified, sync only them, or \
+                        their containing file systems.",
+                    )
+                    .num_args(0..),
+            ])
+    }
+
+    fn run(&self, matches: Option<&clap::ArgMatches>) -> Result<(), Box<dyn Error>> {
+        let Some(matches) = matches else {
+            return Err(Box::new(io::Error::new(io::ErrorKind::Other, "no input")));
+        };
+        if let Some(files) = matches.get_many::<String>("FILE") {
+            for f in files {
+                let file = CString::new(f.as_bytes())?;
+                if matches.get_flag("data") {
+                    let rc = unsafe {
+                        let fd = libc::open(file.as_ptr(), libc::O_RDWR | libc::O_NOATIME);
+                        libc::fdatasync(fd)
+                    };
+                    if rc != 0 {
+                        return Err(Box::new(io::Error::last_os_error()));
+                    }
+                } else if matches.get_flag("fs") {
+                    let rc = unsafe {
+                        let fd = libc::open(file.as_ptr(), libc::O_RDWR | libc::O_NOATIME);
+                        libc::syncfs(fd)
+                    };
+                    if rc != 0 {
+                        return Err(Box::new(io::Error::last_os_error()));
+                    }
+                } else {
+                    let rc = unsafe {
+                        let fd = libc::open(file.as_ptr(), libc::O_RDWR | libc::O_NOATIME);
+                        libc::fsync(fd)
+                    };
+                    if rc != 0 {
+                        return Err(Box::new(io::Error::last_os_error()));
+                    }
+                }
+            }
+        } else {
+            unsafe { libc::sync(); }
+        }
+        Ok(())
+    }
+
+    fn path(&self) -> Option<crate::Path> {
+        Some(crate::Path::Bin)
+    }
+}