The Shredded Note

Before it was shut down, a courier daemon shredded a note into its own log. Every character of the note sits on its own SHARD line in /root/case/shards.log, shuffled in among about 1,500 lines of noise, with gappy sequence numbers. The note is the bytes taken in increasing numeric seq order. Other lines carry seq= too, so only the SHARD lines count.

Record your work under /root/case:

1. Write /root/case/reassemble.sh: given the path of a log in this format as its one argument, it prints the reassembled note. Grading runs it with bash on a brand-new log generated at grading time, so it must work on any log in this format, not just this one.

2. Run it on /root/case/shards.log and save the note (the flag) to /root/case/flag.txt.

Any tools are fine: grep, sed, awk, sort, a while-read loop, python3. See /root/case/brief.txt.