diff --git a/Cargo.lock b/Cargo.lock
index 77767c8..af0c84c 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -66,6 +66,12 @@ version = "0.1.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "a6d640bee2da49f60a4068a7fae53acde8982514ab7bae8b8cea9e88cbcfd799"
 
+[[package]]
+name = "autocfg"
+version = "1.1.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "d468802bab17cbc0cc575e9b053f41e72aa36bfa6b7f55e3529ffa43161b97fa"
+
 [[package]]
 name = "bitflags"
 version = "1.3.2"
@@ -87,6 +93,18 @@ dependencies = [
  "libc",
 ]
 
+[[package]]
+name = "cfg-if"
+version = "0.1.10"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "4785bdd1c96b2a846b2bd7cc02e86b6b3dbf14e7e53446c4f54c92a361040822"
+
+[[package]]
+name = "cfg-if"
+version = "1.0.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "baf1de4339761588bc0619e3cbc0120ee582ebb74b53b4efbf79117bd2da40fd"
+
 [[package]]
 name = "clap"
 version = "4.3.19"
@@ -152,8 +170,59 @@ dependencies = [
  "ecoji",
  "indoc",
  "itertools",
+ "sysinfo",
+ "which",
+]
+
+[[package]]
+name = "crossbeam-channel"
+version = "0.5.8"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "a33c2bf77f2df06183c3aa30d1e96c0695a313d4f9c453cc3762a6db39f99200"
+dependencies = [
+ "cfg-if 1.0.0",
+ "crossbeam-utils",
+]
+
+[[package]]
+name = "crossbeam-deque"
+version = "0.8.3"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "ce6fd6f855243022dcecf8702fef0c297d4338e226845fe067f6341ad9fa0cef"
+dependencies = [
+ "cfg-if 1.0.0",
+ "crossbeam-epoch",
+ "crossbeam-utils",
+]
+
+[[package]]
+name = "crossbeam-epoch"
+version = "0.9.15"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "ae211234986c545741a7dc064309f67ee1e5ad243d0e48335adc0484d960bcc7"
+dependencies = [
+ "autocfg 1.1.0",
+ "cfg-if 1.0.0",
+ "crossbeam-utils",
+ "memoffset",
+ "scopeguard",
+]
+
+[[package]]
+name = "crossbeam-utils"
+version = "0.8.16"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "5a22b2d63d4d1dc0b7f1b6b2747dd0088008a9be28b6ddf0b1e7d335e3037294"
+dependencies = [
+ "cfg-if 1.0.0",
 ]
 
+[[package]]
+name = "doc-comment"
+version = "0.3.3"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "fea41bba32d969b513997752735605054bc0dfa92b4c56bf1189f2e174be7a10"
+
 [[package]]
 name = "ecoji"
 version = "1.0.0"
@@ -247,6 +316,34 @@ version = "0.4.5"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "57bcfdad1b858c2db7c38303a6d2ad4dfaf5eb53dfeb0910128b2c26d6158503"
 
+[[package]]
+name = "memoffset"
+version = "0.9.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "5a634b1c61a95585bd15607c6ab0c4e5b226e695ff2800ba0cdccddf208c406c"
+dependencies = [
+ "autocfg 1.1.0",
+]
+
+[[package]]
+name = "ntapi"
+version = "0.3.7"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "c28774a7fd2fbb4f0babd8237ce554b73af68021b5f695a3cebd6c59bac0980f"
+dependencies = [
+ "winapi",
+]
+
+[[package]]
+name = "num_cpus"
+version = "1.16.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "4161fcb6d602d4d2081af7c3a45852d875a03dd337a6bfdd6e06407b61342a43"
+dependencies = [
+ "hermit-abi",
+ "libc",
+]
+
 [[package]]
 name = "once_cell"
 version = "1.18.0"
@@ -315,7 +412,7 @@ version = "0.6.5"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "6d71dacdc3c88c1fde3885a3be3fbab9f35724e6ce99467f7d9c5026132184ca"
 dependencies = [
- "autocfg",
+ "autocfg 0.1.2",
  "libc",
  "rand_chacha",
  "rand_core 0.4.2",
@@ -334,7 +431,7 @@ version = "0.1.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "556d3a1ca6600bfcbab7c7c91ccb085ac7fbbcd70e008a98742e7847f4f7bcef"
 dependencies = [
- "autocfg",
+ "autocfg 0.1.2",
  "rand_core 0.3.1",
 ]
 
@@ -402,7 +499,7 @@ version = "0.1.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "abf9b09b01790cfe0364f52bf32995ea3c39f4d2dd011eac241d2914146d0b44"
 dependencies = [
- "autocfg",
+ "autocfg 0.1.2",
  "rand_core 0.4.2",
 ]
 
@@ -415,6 +512,28 @@ dependencies = [
  "rand_core 0.3.1",
 ]
 
+[[package]]
+name = "rayon"
+version = "1.7.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "1d2df5196e37bcc87abebc0053e20787d73847bb33134a69841207dd0a47f03b"
+dependencies = [
+ "either",
+ "rayon-core",
+]
+
+[[package]]
+name = "rayon-core"
+version = "1.11.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "4b8f95bd6966f5c87776639160a66bd8ab9895d9d4ab01ddba9fc60661aebe8d"
+dependencies = [
+ "crossbeam-channel",
+ "crossbeam-deque",
+ "crossbeam-utils",
+ "num_cpus",
+]
+
 [[package]]
 name = "rdrand"
 version = "0.4.0"
@@ -437,6 +556,12 @@ dependencies = [
  "windows-sys",
 ]
 
+[[package]]
+name = "scopeguard"
+version = "1.2.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "94143f37725109f92c262ed2cf5e59bce7498c01bcc1502d7b9afe439a4e9f49"
+
 [[package]]
 name = "siphasher"
 version = "0.2.3"
@@ -460,6 +585,21 @@ dependencies = [
  "unicode-ident",
 ]
 
+[[package]]
+name = "sysinfo"
+version = "0.13.4"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "1cac193374347e7c263c5f547524f36ff8ec6702d56c8799c8331d26dffe8c1e"
+dependencies = [
+ "cfg-if 0.1.10",
+ "doc-comment",
+ "libc",
+ "ntapi",
+ "once_cell",
+ "rayon",
+ "winapi",
+]
+
 [[package]]
 name = "unicode-ident"
 version = "1.0.11"
@@ -472,11 +612,20 @@ version = "0.2.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "711b9620af191e0cdc7468a8d14e709c3dcdb115b36f838e601583af800a370a"
 
+[[package]]
+name = "which"
+version = "3.1.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "d011071ae14a2f6671d0b74080ae0cd8ebf3a6f8c9589a2cd45f23126fe29724"
+dependencies = [
+ "libc",
+]
+
 [[package]]
 name = "winapi"
-version = "0.3.6"
+version = "0.3.9"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "92c1eb33641e276cfa214a0522acad57be5c56b10cb348b3c5117db75f3ac4b0"
+checksum = "5c839a674fcd7a98952e593242ea400abe93992746761e38641405d28b00f419"
 dependencies = [
  "winapi-i686-pc-windows-gnu",
  "winapi-x86_64-pc-windows-gnu",
diff --git a/Cargo.toml b/Cargo.toml
index 6d084c7..b8061ed 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -14,6 +14,10 @@ clap = { version = "4.0", features = ["derive"] }
 ecoji = "1.0.0"
 itertools = "0.10.5"
 
+[target.'cfg(unix)'.dependencies]
+sysinfo = "0.13.1"
+which = { version = "3.1.1", default-features = false }
+
 [dev-dependencies]
 indoc = "2.0.3"
 
diff --git a/Readme.md b/Readme.md
index cf9da23..aad84af 100644
--- a/Readme.md
+++ b/Readme.md
@@ -25,3 +25,27 @@ md5sum [file] | coloursum
 ```
 
 Coloursum also prints full usage information if you run `coloursum --help`.
+
+### Shell Integration
+
+You can also integrate coloursum into your shell, to output colourful checksums by default!
+
+By default, it will search for known checksum commands' presence, and generate shell functions for those which are found.
+
+If this behaviour is not acceptable, or your checksum command is not in the list, you can optionally specify a checksum command as the last argument to `coloursum shell-setup` to generate a shell function just for it.
+
+#### bash, zsh, and other similar shells
+
+Add this line to your ~/.bash_profile, ~/.zshrc or equivalent file:
+
+```sh
+eval "$(coloursum --mode=1password shell-setup)"
+```
+
+#### fish shell
+
+Add this line to ~/.config/fish/config.fish:
+
+```fish
+status --is-interactive; and coloursum --mode=ecoji shell-setup | source
+```
diff --git a/src/ansi_coloured_line.rs b/src/ansi_coloured_line.rs
index 4271b3c..10c5a16 100644
--- a/src/ansi_coloured_line.rs
+++ b/src/ansi_coloured_line.rs
@@ -56,6 +56,16 @@ impl Line for ANSIColouredLine {
 
 #[cfg(test)]
 mod tests {
+    #[test]
+    fn display_works() {
+        use super::ANSIColouredLine;
+
+        assert_eq!(
+            format!("{}", ANSIColouredLine::from("MD5 (./src/main.rs) = b7527e0e28c09f6f62dd2d4197d5d225".to_string())),
+            "MD5 (./src/main.rs) = \u{1b}[38;5;183mb7\u{1b}[0m\u{1b}[38;5;82m52\u{1b}[0m\u{1b}[38;5;126m7e\u{1b}[0m\u{1b}[38;5;14m0e\u{1b}[0m\u{1b}[38;5;40m28\u{1b}[0m\u{1b}[38;5;192mc0\u{1b}[0m\u{1b}[38;5;159m9f\u{1b}[0m\u{1b}[38;5;111m6f\u{1b}[0m\u{1b}[38;5;98m62\u{1b}[0m\u{1b}[38;5;221mdd\u{1b}[0m\u{1b}[38;5;45m2d\u{1b}[0m\u{1b}[38;5;65m41\u{1b}[0m\u{1b}[38;5;151m97\u{1b}[0m\u{1b}[38;5;213md5\u{1b}[0m\u{1b}[38;5;210md2\u{1b}[0m\u{1b}[38;5;37m25\u{1b}[0m"
+        )
+    }
+
     #[test]
     fn format_hash_works() {
         use super::ANSIColouredLine;
diff --git a/src/base_line.rs b/src/base_line.rs
index 16a811b..71c236e 100644
--- a/src/base_line.rs
+++ b/src/base_line.rs
@@ -92,6 +92,18 @@ fn find_sum_prefixed_line(line: &str) -> Option<usize> {
 
 #[cfg(test)]
 mod tests {
+    #[test]
+    fn from_string_works() {
+        use super::FormattableLine;
+
+        let string = "MD5 (./src/main.rs) = b7527e0e28c09f6f62dd2d4197d5d225".to_string();
+        let line = FormattableLine::from(string.clone());
+
+        assert_eq!(line.contents, string);
+        assert_eq!(line.formattable_start, Some(22));
+        assert_eq!(line.formattable_end, None);
+    }
+
     #[test]
     fn find_bsd_tag_line_works() {
         use super::find_bsd_tag_line;
diff --git a/src/ecoji_line.rs b/src/ecoji_line.rs
index 1ff25e6..c229b27 100644
--- a/src/ecoji_line.rs
+++ b/src/ecoji_line.rs
@@ -56,6 +56,21 @@ impl Line for EcojiLine {
 
 #[cfg(test)]
 mod tests {
+    #[test]
+    fn display_works() {
+        use super::EcojiLine;
+
+        assert_eq!(
+            format!(
+                "{}",
+                EcojiLine::from(
+                    "MD5 (./src/main.rs) = b7527e0e28c09f6f62dd2d4197d5d225".to_string()
+                )
+            ),
+            "MD5 (./src/main.rs) = 😨🏸🤰📺🙎📇🦎😨🍽🇮📆💣🍜☕☕☕"
+        )
+    }
+
     #[test]
     fn format_hash_works() {
         use super::EcojiLine;
diff --git a/src/main.rs b/src/main.rs
index 66adedf..0f9a5b7 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -11,9 +11,29 @@ enum FormattingMode {
     OnePassword,
 }
 
+impl ToString for FormattingMode {
+    fn to_string(&self) -> String {
+        match self {
+            FormattingMode::ANSIColours => "ansi-colours",
+            FormattingMode::Ecoji => "ecoji",
+            FormattingMode::OnePassword => "1password",
+        }
+        .to_string()
+    }
+}
+
 #[derive(Parser, Debug)]
 #[clap(version)]
 struct Options {
+    #[clap(flatten)]
+    main_options: MainOptions,
+
+    #[clap(subcommand)]
+    cmd: Option<Subcommand>,
+}
+
+#[derive(Parser, Debug)]
+struct MainOptions {
     /// What sort of formatting to use for checksum values.
     #[clap(
         short,
@@ -25,9 +45,44 @@ struct Options {
     mode: FormattingMode,
 }
 
-fn main() -> io::Result<()> {
-    let options = Options::parse();
+#[derive(Parser, Debug)]
+#[clap(rename_all = "kebab-case")]
+enum Subcommand {
+    /// Configure the current shell environment to use coloursum
+    ///
+    /// Automatically detects the currently used shell, and configures
+    /// it to use coloursum with the specified options
+    ///
+    /// For example, to configure your zsh shell to use 1Password-style
+    /// formatting, add the line
+    /// `eval "$(coloursum --mode 1password shell-setup)"` to your ~/.zshrc
+    /// file
+    ///
+    /// Or, to configure your fish shell to use ecoji formatting, but only
+    /// for `sha256sum`, add the line
+    /// `status --is-interactive; and coloursum --mode ecoji shell-setup sha256sum | source`
+    /// to your ~/.config/fish/config.fish file
+    #[cfg(unix)]
+    #[clap(override_usage = r#"
+    # for bash, zsh, and other similar shells
+    eval "$(coloursum [OPTIONS] shell-setup [command])"
 
+    # for fish
+    status --is-interactive; and coloursum [OPTIONS] shell-setup [command] | source"#)]
+    ShellSetup(ShellSetupOptions),
+}
+
+#[derive(Parser, Debug)]
+struct ShellSetupOptions {
+    /// Checksum command to set up shell integration for. If omitted, coloursum
+    /// will attempt to automatically detect installed checksum commands.
+    /// If specified, coloursum will configure only that checksum command.
+    /// You may call shell-setup repeatedly to configure integration for
+    /// multiple manually-configured checksum commands.
+    command: Option<String>,
+}
+
+fn coloursum(options: &MainOptions) -> io::Result<()> {
     let stdin = io::stdin();
     let locked_stdin = stdin.lock();
 
@@ -40,3 +95,117 @@ fn main() -> io::Result<()> {
         FormattingMode::OnePassword => OnePasswordLine::coloursum(locked_stdin, locked_stdout),
     }
 }
+
+#[cfg(unix)]
+static SUM_EXECNAMES: &[&str] = &[
+    "md5",
+    "md5sum",
+    "gmd5sum",
+    "shasum",
+    "sha1sum",
+    "gsha1sum",
+    "sha2",
+    "sha256sum",
+    "gsha256sum",
+    "sha224sum",
+    "gsha224sum",
+    "sha384sum",
+    "gsha384sum",
+    "sha512sum",
+    "gsha512sum",
+];
+
+#[cfg(unix)]
+fn shell_setup(
+    options: &MainOptions,
+    shell_setup_options: &ShellSetupOptions,
+) -> Result<(), std::io::Error> {
+    // detect the calling shell's name
+    let shell_name = match get_shell_name() {
+        Some(shell_name) => shell_name,
+        // fall back to "sh" if not detectable/something weird happens
+        None => "sh".to_string(),
+    };
+
+    println!("# coloursum: generated setup for `{}`", shell_name);
+
+    if let Some(command) = &shell_setup_options.command {
+        print_shell_function(options, shell_name.as_ref(), command.to_string());
+    } else {
+        for executable in SUM_EXECNAMES {
+            if let Ok(_path) = which::which(executable) {
+                print_shell_function(options, shell_name.as_ref(), (*executable).to_string())
+            }
+        }
+    }
+
+    Ok(())
+}
+
+#[cfg(unix)]
+fn get_shell_name() -> Option<String> {
+    use sysinfo::{ProcessExt, System, SystemExt};
+
+    let system = System::new_with_specifics(sysinfo::RefreshKind::new().with_processes());
+
+    // find the current process by pid, fall back to 0
+    // (which is invalid/reserved, so will return None early)
+    let process = system.get_process(sysinfo::get_current_pid().unwrap_or(0))?;
+
+    // find the parent process via the current process's parent ID
+    let parent = system.get_process(process.parent()?)?;
+
+    // and if we make it all the way here, return some name
+    Some(parent.name().to_string())
+}
+
+#[cfg(unix)]
+fn print_shell_function(options: &MainOptions, shell_name: &str, command: String) {
+    // TODO: work out how to print this losslessly
+    let exe_name = match std::env::current_exe() {
+        Ok(path) => path.to_string_lossy().into_owned(),
+        Err(_) => "coloursum".to_string(),
+    };
+
+    match shell_name {
+        "fish" => println!(
+            "function {0}\n\
+            \tcommand {0} $argv | {1} --mode {2}\n\
+            end",
+            command,
+            exe_name,
+            options.mode.to_string()
+        ),
+        "ksh" => println!(
+            "function {0} {{\n\
+            \tcommand {0} \"$@\" | {1} --mode {2}\n\
+            }}",
+            command,
+            exe_name,
+            options.mode.to_string()
+        ),
+        _ => println!(
+            "function {0}() {{\n\
+            \tcommand {0} \"$@\" | {1} --mode {2}\n\
+            }}",
+            command,
+            exe_name,
+            options.mode.to_string()
+        ),
+    }
+}
+
+fn main() -> Result<(), std::io::Error> {
+    let options = Options::parse();
+
+    if let Some(command) = options.cmd {
+        match command {
+            #[cfg(unix)]
+            Subcommand::ShellSetup(shell_setup_options) => {
+                shell_setup(&options.main_options, &shell_setup_options)
+            }
+        }
+    } else {
+        coloursum(&options.main_options)
+    }
+}
diff --git a/src/onepassword_line.rs b/src/onepassword_line.rs
index 3e92289..eab6069 100644
--- a/src/onepassword_line.rs
+++ b/src/onepassword_line.rs
@@ -45,6 +45,16 @@ impl Line for OnePasswordLine {
 
 #[cfg(test)]
 mod tests {
+    #[test]
+    fn display_works() {
+        use super::OnePasswordLine;
+
+        assert_eq!(
+            format!("{}", OnePasswordLine::from("MD5 (./src/main.rs) = b7527e0e28c09f6f62dd2d4197d5d225".to_string())),
+            "MD5 (./src/main.rs) = b\u{1b}[38;5;4m7\u{1b}[0m\u{1b}[38;5;4m5\u{1b}[0m\u{1b}[38;5;4m2\u{1b}[0m\u{1b}[38;5;4m7\u{1b}[0me\u{1b}[38;5;4m0\u{1b}[0me\u{1b}[38;5;4m2\u{1b}[0m\u{1b}[38;5;4m8\u{1b}[0mc\u{1b}[38;5;4m0\u{1b}[0m\u{1b}[38;5;4m9\u{1b}[0mf\u{1b}[38;5;4m6\u{1b}[0mf\u{1b}[38;5;4m6\u{1b}[0m\u{1b}[38;5;4m2\u{1b}[0mdd\u{1b}[38;5;4m2\u{1b}[0md\u{1b}[38;5;4m4\u{1b}[0m\u{1b}[38;5;4m1\u{1b}[0m\u{1b}[38;5;4m9\u{1b}[0m\u{1b}[38;5;4m7\u{1b}[0md\u{1b}[38;5;4m5\u{1b}[0md\u{1b}[38;5;4m2\u{1b}[0m\u{1b}[38;5;4m2\u{1b}[0m\u{1b}[38;5;4m5\u{1b}[0m"
+        )
+    }
+
     #[test]
     fn format_hash_works() {
         use super::OnePasswordLine;