Add Output The Last N Bytes Of A Large File as a Unix TIL

unix/output-the-last-n-bytes-of-a-large-file.md

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+# Output The Last N Bytes Of A Large File
+
+After creating a massive JSON file as part of a data export, I wanted to check
+the timestamp of the last value in the file. However, even for Vim, the file
+was big and it was taking a while to bring the whole thing into memory.
+
+I didn't really need to open it in a full-fledged editor, I just needed to grab
+the trailing bits (bytes!) of the file until I could see enough data to verify
+the export.
+
+The `tail` command is a great tool for this because it can quickly read
+information from the end of a file. The `-c` flag in particular allows you to
+grab the last N bytes of the file and output them.
+
+So, I started with:
+
+```bash
+$ tail -c 100 data.json
+```
+
+That didn't quite show me enough info, so I bumped it up:
+
+```bash
+$ tail -c 1000 data.json
+```
+
+That time I was able to see enough to verify the export.
+
+Both commands ran instantaneously, meanwhile my editor was still opening the
+file.
+
+See `man tail` for more details.