diff --git a/README.md b/README.md
index 526f37f..b8b8f23 100644
--- a/README.md
+++ b/README.md
@@ -1,3 +1,16 @@
 # nyan
 
-A small wrapper to make cat prettier.
\ No newline at end of file
+A small wrapper to make cat prettier while concatenating large files.
+
+# Features
+* Pipes `cat` through `pv` to make a whole-operation progress bar with a time estimate.
+* Pre-checks files _before_ passing them to `cat`. No more partial concatenations!
+
+# Usage
+`nyan -o [OUTPUT_FILE] [INPUT_FILE]...`
+
+An output file defined with `-o` is required. This wrapper is designed for non-human-readable files
+and as such does not output to stdout.
+
+# Dependencies
+* `pv` is required for the progress bar.
diff --git a/nyan b/nyan
new file mode 100755
index 0000000..6c33f0e
--- /dev/null
+++ b/nyan
@@ -0,0 +1,39 @@
+#!/bin/bash
+optstring="o:"
+declare -i abort=0
+
+# TODO: Check for dependencies pv and stat.
+# TODO: Add help option to display usage.
+# TODO: Consider a switch for per-file progress bars rather than a whole-operation one.
+
+while getopts ${optstring} args; do
+	case $args in
+		o) output_file=${OPTARG} ;;
+		:) echo "Output file required." ;;
+	esac
+done
+shift $((OPTIND-1))
+
+echo "Concatenating files..."
+declare -i total_size=0
+for fname in "$@"; do
+	if [ ! -e "$fname" ]; then
+		abort=1
+		echo "${fname} does not exist."
+	elif [ -d "$fname" ]; then
+		abort=1
+		echo "${fname} is a directory."
+	else
+		current_file_size=$(stat -c%s "$fname")
+		total_size=$((total_size+current_file_size))
+		# TODO: Use something more legible than bytes.
+		echo "Adding ${fname} at ${total_size}b."
+	fi
+done
+
+if [ $abort -eq 0 ]; then
+	cat "$@" | pv -epts "$total_size" > "$output_file"
+	echo "Done!"
+else
+	echo "Errors occurred, concatenation aborted."
+fi