diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index bf8c2004..a98a2f56 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -193,6 +193,10 @@ jobs:
       shell: bash
       run: ci/test-complete
 
+    - name: Print hostname detected by grep-cli crate
+      shell: bash
+      run: ${{ env.CARGO }} test --manifest-path crates/cli/Cargo.toml ${{ env.TARGET_FLAGS }} --lib print_hostname -- --nocapture
+
   rustfmt:
     runs-on: ubuntu-latest
     steps:
diff --git a/Cargo.lock b/Cargo.lock
index 2f30fbfd..f2019025 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -187,6 +187,7 @@ version = "0.1.9"
 dependencies = [
  "bstr",
  "globset",
+ "libc",
  "log",
  "termcolor",
  "winapi-util",
diff --git a/crates/cli/Cargo.toml b/crates/cli/Cargo.toml
index 0ce69873..8e576b66 100644
--- a/crates/cli/Cargo.toml
+++ b/crates/cli/Cargo.toml
@@ -21,3 +21,6 @@ termcolor = "1.3.0"
 
 [target.'cfg(windows)'.dependencies.winapi-util]
 version = "0.1.6"
+
+[target.'cfg(unix)'.dependencies.libc]
+version = "0.2.148"
diff --git a/crates/cli/src/hostname.rs b/crates/cli/src/hostname.rs
new file mode 100644
index 00000000..37ad54c7
--- /dev/null
+++ b/crates/cli/src/hostname.rs
@@ -0,0 +1,85 @@
+use std::{ffi::OsString, io};
+
+/// Returns the hostname of the current system.
+///
+/// It is unusual, although technically possible, for this routine to return
+/// an error. It is difficult to list out the error conditions, but one such
+/// possibility is platform support.
+///
+/// # Platform specific behavior
+///
+/// On Windows, this currently uses the "physical DNS hostname" computer name.
+/// This may change in the future.
+///
+/// On Unix, this returns the result of the `gethostname` function from the
+/// `libc` linked into the program.
+pub fn hostname() -> io::Result<OsString> {
+    #[cfg(windows)]
+    {
+        use winapi_util::sysinfo::{get_computer_name, ComputerNameKind};
+        get_computer_name(ComputerNameKind::PhysicalDnsHostname)
+    }
+    #[cfg(unix)]
+    {
+        gethostname()
+    }
+    #[cfg(not(any(windows, unix)))]
+    {
+        io::Error::new(
+            io::ErrorKind::Other,
+            "hostname could not be found on unsupported platform",
+        )
+    }
+}
+
+#[cfg(unix)]
+fn gethostname() -> io::Result<OsString> {
+    use std::os::unix::ffi::OsStringExt;
+
+    // SAFETY: There don't appear to be any safety requirements for calling
+    // sysconf.
+    let limit = unsafe { libc::sysconf(libc::_SC_HOST_NAME_MAX) };
+    if limit == -1 {
+        // It is in theory possible for sysconf to return -1 for a limit but
+        // *not* set errno, in which case, io::Error::last_os_error is
+        // indeterminate. But untangling that is super annoying because std
+        // doesn't expose any unix-specific APIs for inspecting the errno. (We
+        // could do it ourselves, but it just doesn't seem worth doing?)
+        return Err(io::Error::last_os_error());
+    }
+    let Ok(maxlen) = usize::try_from(limit) else {
+        let msg = format!("host name max limit ({}) overflowed usize", limit);
+        return Err(io::Error::new(io::ErrorKind::Other, msg));
+    };
+    // maxlen here includes the NUL terminator.
+    let mut buf = vec![0; maxlen];
+    // SAFETY: The pointer we give is valid as it is derived directly from a
+    // Vec. Similarly, `maxlen` is the length of our Vec, and is thus valid
+    // to write to.
+    let rc = unsafe {
+        libc::gethostname(buf.as_mut_ptr().cast::<libc::c_char>(), maxlen)
+    };
+    if rc == -1 {
+        return Err(io::Error::last_os_error());
+    }
+    // POSIX says that if the hostname is bigger than `maxlen`, then it may
+    // write a truncate name back that is not necessarily NUL terminated (wtf,
+    // lol). So if we can't find a NUL terminator, then just give up.
+    let Some(zeropos) = buf.iter().position(|&b| b == 0) else {
+        let msg = "could not find NUL terminator in hostname";
+        return Err(io::Error::new(io::ErrorKind::Other, msg));
+    };
+    buf.truncate(zeropos);
+    buf.shrink_to_fit();
+    Ok(OsString::from_vec(buf))
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn print_hostname() {
+        println!("{:?}", hostname().unwrap());
+    }
+}
diff --git a/crates/cli/src/lib.rs b/crates/cli/src/lib.rs
index a16d4c7d..b335a3f5 100644
--- a/crates/cli/src/lib.rs
+++ b/crates/cli/src/lib.rs
@@ -144,6 +144,7 @@ error message is crafted that typically tells the user how to fix the problem.
 
 mod decompress;
 mod escape;
+mod hostname;
 mod human;
 mod pattern;
 mod process;
@@ -155,6 +156,7 @@ pub use crate::{
         DecompressionReader, DecompressionReaderBuilder,
     },
     escape::{escape, escape_os, unescape, unescape_os},
+    hostname::hostname,
     human::{parse_human_readable_size, ParseSizeError},
     pattern::{
         pattern_from_bytes, pattern_from_os, patterns_from_path,