diff --git a/Cargo.lock b/Cargo.lock
index 18230ed..c337d7f 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -120,6 +120,27 @@ dependencies = [
  "owo-colors",
 ]
 
+[[package]]
+name = "dirs-next"
+version = "2.0.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "b98cf8ebf19c3d1b223e151f99a4f9f0690dca41414773390fc824184ac833e1"
+dependencies = [
+ "cfg-if 1.0.0",
+ "dirs-sys-next",
+]
+
+[[package]]
+name = "dirs-sys-next"
+version = "0.1.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "4ebda144c4fe02d1f7ea1a7d9641b6fc6b580adcfa024ae48797ecdeb6825b4d"
+dependencies = [
+ "libc",
+ "redox_users",
+ "winapi 0.3.9",
+]
+
 [[package]]
 name = "dirstat"
 version = "0.1.0"
@@ -136,6 +157,7 @@ dependencies = [
  "num_cpus",
  "once_cell",
  "pin-project",
+ "rustyline",
  "serde",
  "serde_cbor",
  "smallvec",
@@ -158,6 +180,16 @@ version = "1.0.7"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "3f9eec918d3f24069decb9af1554cad7c880e2da24a9afd88aca000531ab82c1"
 
+[[package]]
+name = "fs2"
+version = "0.4.3"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "9564fc758e15025b46aa6643b1b77d047d1a56a1aea6e01002ac0c7026876213"
+dependencies = [
+ "libc",
+ "winapi 0.3.9",
+]
+
 [[package]]
 name = "fs_extra"
 version = "1.2.0"
@@ -275,6 +307,17 @@ dependencies = [
  "slab",
 ]
 
+[[package]]
+name = "getrandom"
+version = "0.2.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "c9495705279e7140bf035dde1f6e750c162df8b625267cd52cc44e0b156732c8"
+dependencies = [
+ "cfg-if 1.0.0",
+ "libc",
+ "wasi",
+]
+
 [[package]]
 name = "gimli"
 version = "0.23.0"
@@ -464,6 +507,18 @@ dependencies = [
  "winapi 0.3.9",
 ]
 
+[[package]]
+name = "nix"
+version = "0.19.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "b2ccba0cfe4fdf15982d1674c69b1fd80bad427d293849982668dfe454bd61f2"
+dependencies = [
+ "bitflags",
+ "cc",
+ "cfg-if 1.0.0",
+ "libc",
+]
+
 [[package]]
 name = "num_cpus"
 version = "1.13.0"
@@ -566,12 +621,58 @@ dependencies = [
  "proc-macro2",
 ]
 
+[[package]]
+name = "redox_syscall"
+version = "0.2.5"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "94341e4e44e24f6b591b59e47a8a027df12e008d73fd5672dbea9cc22f4507d9"
+dependencies = [
+ "bitflags",
+]
+
+[[package]]
+name = "redox_users"
+version = "0.4.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "528532f3d801c87aec9def2add9ca802fe569e44a544afe633765267840abe64"
+dependencies = [
+ "getrandom",
+ "redox_syscall",
+]
+
 [[package]]
 name = "rustc-demangle"
 version = "0.1.18"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "6e3bad0ee36814ca07d7968269dd4b7ec89ec2da10c4bb613928d3077083c232"
 
+[[package]]
+name = "rustyline"
+version = "7.1.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "8227301bfc717136f0ecbd3d064ba8199e44497a0bdd46bb01ede4387cfd2cec"
+dependencies = [
+ "bitflags",
+ "cfg-if 1.0.0",
+ "dirs-next",
+ "fs2",
+ "libc",
+ "log",
+ "memchr",
+ "nix",
+ "scopeguard",
+ "unicode-segmentation",
+ "unicode-width",
+ "utf8parse",
+ "winapi 0.3.9",
+]
+
+[[package]]
+name = "scopeguard"
+version = "1.1.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "d29ab0c6d3fc0ee92fe66e2d99f700eab17a8d57d1c1d3b748380fb20baa78cd"
+
 [[package]]
 name = "serde"
 version = "1.0.123"
@@ -680,12 +781,36 @@ dependencies = [
  "syn",
 ]
 
+[[package]]
+name = "unicode-segmentation"
+version = "1.7.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "bb0d2e7be6ae3a5fa87eed5fb451aff96f2573d2694942e40543ae0bbe19c796"
+
+[[package]]
+name = "unicode-width"
+version = "0.1.8"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "9337591893a19b88d8d87f2cec1e73fad5cdfd10e5a6f349f498ad6ea2ffb1e3"
+
 [[package]]
 name = "unicode-xid"
 version = "0.2.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "f7fe0bb3479651439c9112f72b6c505038574c9fbb575ed1bf3b797fa39dd564"
 
+[[package]]
+name = "utf8parse"
+version = "0.2.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "936e4b492acfd135421d8dca4b1aa80a7bfc26e702ef3af710e0752684df5372"
+
+[[package]]
+name = "wasi"
+version = "0.10.2+wasi-snapshot-preview1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "fd6fbd9a79829dd1ad0cc20627bf1ed606756a7f77edff7b66b7064f9cb327c6"
+
 [[package]]
 name = "winapi"
 version = "0.2.8"
diff --git a/Cargo.toml b/Cargo.toml
index 35eb35b..13ab3bd 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -15,6 +15,9 @@ panic = "unwind"
 [features]
 default = ["splash", "inspect", "defer-drop", "jemalloc", "prealloc"]
 
+# When using the REPL to inspect graphs, save command history.
+save-history = []
+
 # Use jemalloc as global allocator instead of system allocator.
 # May potentially cause some speedups and better memory profile on large runs.
 jemalloc = ["jemallocator"]
@@ -44,6 +47,7 @@ memmap = {version = "0.7.0", optional = true}
 num_cpus = "1.13.0"
 once_cell = "1.5.2"
 pin-project = "1.0.5"
+rustyline = "7.1.0"
 serde = {version = "1.0.123", features=["derive"], optional=true}
 serde_cbor = {version = "0.11.1", optional=true}
 smallvec = "1.6.1"
diff --git a/src/info.rs b/src/info/mod.rs
similarity index 97%
rename from src/info.rs
rename to src/info/mod.rs
index 8367cb8..27087a7 100644
--- a/src/info.rs
+++ b/src/info/mod.rs
@@ -4,6 +4,8 @@ use super::*;
 use data::HierarchicalINodeGraph;
 use config::Config;
 
+pub mod repl;
+
 /// Print the most basic info
 pub fn print_basic_max_info(cfg: &Config, graph: &HierarchicalINodeGraph)
 {
diff --git a/src/info/repl.rs b/src/info/repl.rs
new file mode 100644
index 0000000..d72070b
--- /dev/null
+++ b/src/info/repl.rs
@@ -0,0 +1,124 @@
+//! Graph inspection REPL
+use super::*;
+use std::{fmt, error};
+use std::path::PathBuf;
+use std::io;
+
+use rustyline::error::ReadlineError;
+use rustyline::Editor;
+
+/// Default history file name
+///
+/// # Path lookup
+/// * To make this an absolute path, start it with `/`
+/// * To make this path relative to the user's home directory, start it with `~/` (Note: If we are unable to find the user's home directory, it is considered a lookup **failure** (*not* a **disable**) and `calculate_history_path()` will return `Err`.)
+/// * Otherwise, the path is taken relative to the current working directory
+///
+/// # Notes
+/// This is only used when the `save-history` feature is enabled.
+const DEFAULT_HISTORY_FILE: &'static str = "~/.dirstat_history";
+
+/// Get the path to the history file.
+///
+/// # Lookup
+/// * If the `DIRSTAT_HISTORY` envvar is set and not empty, use this file path.
+/// * If the `DIRSTAT_HISTORY` envvar is set and empty, saving history is considered **disabled**, we return `Ok(None)`.
+/// * Otherwise, refer to lookup rules for `DEFAULT_HISTORY_FILE`.
+pub fn calculate_history_path() -> io::Result<Option<PathBuf>>
+{
+    cfg_if! {
+	if #[cfg(feature="save-history")] {
+	    todo!()
+	} else {
+	    unreachable!("Tried to calculate repl history path when binary was compiled with history saving perma-disabled.")
+	}
+    }
+}
+
+/// Inspect the graph with commands
+pub fn inspect(cfg: &Config, graph: &HierarchicalINodeGraph) -> Result<(), ReplExitError>
+{
+    let mut repl = Editor::<()>::new(); //TODO: Change `()` to our completer, when we have a decent idea of how they'll work.
+
+    cfg_if! {
+	if #[cfg(feature="save-history")] {
+	    let history_path = match calculate_history_path() {
+		Ok(Some(path)) => {
+		    if let Err(err) = repl.load_history(&path)
+		    {
+			cfg_eprintln!(cfg, "Failed to load repl history from {:?}: {}", path, err);
+		    }
+		    Some(path)
+		},
+		Ok(None) => None,
+		Err(err)
+		{
+		    cfg_eprintln!(cfg, "Failed to find repl history: {}", err);
+		    None
+		}
+	    }
+	}
+    }
+    
+    let res: Result<(), ReplExitError> = try {	
+	loop {
+	    let line = repl.readline("> ")?; 
+	    repl.add_history_entry(&line);
+
+	    //TODO: How to interpret commands?
+	    todo!("Interpret commands from `line`.");
+	}
+    };
+    
+    cfg_if! {
+	if #[cfg(feature="save-history")] {
+	    if let Some(path) = history_path {
+		if let Err(err) = repl.save_history(&path)
+		{
+		    cfg_eprintln!(cfg, "Failed to save repl history to {:?}: {}", path, err);
+		}
+	    }
+	}
+    }
+
+    res
+}
+
+/// When the inspection repl exists abnormally.
+#[derive(Debug)]
+pub enum ReplExitError
+{
+    ReadLine(ReadlineError),
+}
+
+impl From<ReadlineError> for ReplExitError
+{
+    #[inline] fn from(from: ReadlineError) -> Self
+    {
+	Self::ReadLine(from)
+    }
+}
+
+impl error::Error for ReplExitError
+{
+    fn source(&self) -> Option<&(dyn error::Error + 'static)> {
+	Some(match &self
+	     {
+		 Self::ReadLine(rl) => rl
+	     })
+    }
+}
+impl fmt::Display for ReplExitError
+{
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result
+    {
+	match self
+	{
+	    Self::ReadLine(ReadlineError::Eof) |
+	    Self::ReadLine(ReadlineError::Interrupted) => write!(f, "exit"),
+	    Self::ReadLine(_) => write!(f, "readline error"),
+	}
+    }
+}
+
+
diff --git a/src/main.rs b/src/main.rs
index ae62660..f264790 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -1,3 +1,4 @@
+#![feature(try_blocks)]
 
 #![allow(dead_code)]