diff --git a/src/args.rs b/src/args.rs
index 9f30e86..40ca40b 100644
--- a/src/args.rs
+++ b/src/args.rs
@@ -16,6 +16,9 @@ pub struct Cli {
 
 #[derive(Subcommand)]
 pub enum Commands {
+    #[clap(hide = true)]
+    Postinstall,
+
     /// Build the project and install it locally (into VFS).
     Build(BuildArgs),
 
diff --git a/src/cli.rs b/src/cli.rs
index a8046e3..0bf4dc6 100644
--- a/src/cli.rs
+++ b/src/cli.rs
@@ -6,6 +6,7 @@ use std::path::PathBuf;
 pub fn run_command(vfs: PathBuf, command: &Commands) -> anyhow::Result<()> {
     use Commands::*;
     match command {
+        Postinstall => cmd_postinstall(),
         Build(args) => cmd_build(vfs, args),
         Export(args) => cmd_export(&vfs, args),
         Import(args) => cmd_import(&vfs, args),
diff --git a/src/commands/mod.rs b/src/commands/mod.rs
index e4bab2b..ece4d12 100644
--- a/src/commands/mod.rs
+++ b/src/commands/mod.rs
@@ -11,6 +11,7 @@ mod logs;
 mod monitor;
 mod name;
 mod new;
+mod postinstall;
 mod repl;
 mod runtime;
 mod shots;
@@ -30,6 +31,7 @@ pub use logs::cmd_logs;
 pub use monitor::cmd_monitor;
 pub use name::{cmd_name_generate, cmd_name_get, cmd_name_set};
 pub use new::cmd_new;
+pub use postinstall::cmd_postinstall;
 pub use repl::cmd_repl;
 pub use runtime::{cmd_exit, cmd_id, cmd_launch, cmd_restart, cmd_screenshot};
 pub use shots::cmd_shots_download;
diff --git a/src/commands/postinstall.rs b/src/commands/postinstall.rs
new file mode 100644
index 0000000..76d7907
--- /dev/null
+++ b/src/commands/postinstall.rs
@@ -0,0 +1,148 @@
+use anyhow::{Context, Result, bail};
+use std::{
+    io::Write,
+    path::{Path, PathBuf},
+};
+
+pub fn cmd_postinstall() -> Result<()> {
+    let path = move_self()?;
+    create_alias(&path)?;
+    Ok(())
+}
+
+/// Move the currently running executable into $PATH.
+fn move_self() -> Result<PathBuf> {
+    if let Some(path) = find_writable_path() {
+        move_self_to(&path)?;
+        return Ok(path);
+    }
+    if let Some(home) = std::env::home_dir() {
+        let path = home.join(".local").join("bin");
+        if is_writable(&path) {
+            move_self_to(&path)?;
+            add_path(&path)?;
+            return Ok(path);
+        }
+    }
+    bail!("cannot write writable dir in $PATH")
+}
+
+/// Move the currently running executable into the given path.
+fn move_self_to(new_path: &Path) -> Result<()> {
+    let Some(old_path) = std::env::args().next() else {
+        bail!("cannot access process args");
+    };
+    let old_path = PathBuf::from(old_path);
+    if !old_path.exists() {
+        bail!("the binary is execute not by its path");
+    }
+    let new_path = new_path.join("firefly_cli");
+    std::fs::rename(old_path, new_path).context("move binary")?;
+    Ok(())
+}
+
+/// Create `ff` shortcut for `firefly_cli`.
+fn create_alias(dir_path: &Path) -> Result<()> {
+    #[cfg(unix)]
+    create_alias_unix(dir_path)?;
+    #[cfg(not(unix))]
+    println!("⚠️  The `ff` alias can be created only on UNIX systems.");
+    Ok(())
+}
+
+#[cfg(unix)]
+fn create_alias_unix(dir_path: &Path) -> Result<()> {
+    let old_path = dir_path.join("firefly_cli");
+    let new_path = dir_path.join("ff");
+    std::os::unix::fs::symlink(old_path, new_path)?;
+    Ok(())
+}
+
+/// Find a path in `$PATH` in which the current user can create files.
+fn find_writable_path() -> Option<PathBuf> {
+    let paths = load_paths();
+
+    // Prefer writable paths in the user home directory.
+    if let Some(home) = std::env::home_dir() {
+        for path in &paths {
+            let in_home = path.starts_with(&home);
+            if in_home && is_writable(path) {
+                return Some(path.clone());
+            }
+        }
+    }
+
+    // If no writable paths in the home dir, find a writable path naywhere else.
+    for path in &paths {
+        if is_writable(path) {
+            return Some(path.clone());
+        }
+    }
+
+    // No writable paths in $PATH.
+    None
+}
+
+/// Check if the current user can create files in the given directory.
+fn is_writable(path: &Path) -> bool {
+    let Ok(meta) = std::fs::metadata(path) else {
+        return false;
+    };
+    let readonly = meta.permissions().readonly();
+    if readonly {
+        return false;
+    }
+
+    // Even if the dir is not marked as readonly, file writes to it may still fail.
+    // So, there is only one way to know for sure.
+    let file_path = path.join("_temp-file-by-firefly-cli-pls-delete");
+    let res = std::fs::write(&file_path, "");
+    _ = std::fs::remove_file(file_path);
+    res.is_ok()
+}
+
+/// Read and parse paths from `$PATH`.
+fn load_paths() -> Vec<PathBuf> {
+    let Ok(raw) = std::env::var("PATH") else {
+        return Vec::new();
+    };
+    parse_paths(&raw)
+}
+
+fn parse_paths(raw: &str) -> Vec<PathBuf> {
+    #[cfg(windows)]
+    const SEP: char = ';';
+    #[cfg(not(windows))]
+    const SEP: char = ':';
+
+    let mut paths = Vec::new();
+    for path in raw.split(SEP) {
+        paths.push(PathBuf::from(path));
+    }
+    paths
+}
+
+/// Add the given directory into `$PATH`.
+fn add_path(path: &Path) -> Result<()> {
+    let Some(home) = std::env::home_dir() else {
+        bail!("home dir not found");
+    };
+    let zshrc = home.join(".zshrc");
+    if zshrc.exists() {
+        return add_path_to(&zshrc, path);
+    }
+    let bashhrc = home.join(".bashhrc");
+    if bashhrc.exists() {
+        return add_path_to(&bashhrc, path);
+    }
+    bail!("cannot find .zshrc or .bashrc")
+}
+
+fn add_path_to(profile: &Path, path: &Path) -> Result<()> {
+    let mut file = std::fs::OpenOptions::new().append(true).open(profile)?;
+    let path_bin = path.as_os_str().as_encoded_bytes();
+    file.write_all(b"\n\nexport PATH=\"$PATH:")?;
+    file.write_all(path_bin)?;
+    file.write_all(b"\"\n")?;
+    Ok(())
+}