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