srf_index_hash(1)

✨ srf_index_hash(1) ✨

okay bestie, so this one lives in the Staden io_lib family of man pages, and it's literally just about giving your SRF file a lil glow-up in the form of an index 💅

💖 NAME 💖

srf_index_hash — adds a hash-table index to an SRF file.

🦋 SYNOPSIS 🦋

srf_index_hash [-c] srf_archive

🌸 DESCRIPTION 🌸

so what does this cutie actually do? srf_index_hash adds an index to an SRF file, or — if one's already there — it replaces that existing index with a brand new one. out with the old, in with the new, periodt ✨

now here's the tea for concatenated SRF files: only the index at the very end of the file gets replaced. the internal indices? yeah no, they just sit there, because SRF tools won't consult them anyway 🙈

and what is this index, you ask? it's a hash table that indexes the sequence names only. but plot twist — the name itself does not appear in the index. instead, the index holds the top 7-bits of a 64-bit hash key, plus N-bits that are used to figure out the hash bucket. the way that keeps the index size down to around 10-15 bytes per sequence?? obsessed. iconic. no cap 💖

👑 OPTIONS 👑

• -c — check only mode, bestie. this asks for the index to not be produced, but the checks that happen while creating an index (like looking for duplicate sequence names 👀) still get performed. so you get the vibe check without the commitment 🫶

🎀 AUTHOR 🎀

James Bonfield, Wellcome Trust Sanger Institute

and that's the whole page, fr fr 💜 big shoutout to the Staden io_lib era for this one, dated September 29 — same srf_index_hash(1) energy from top to bottom, slay 🌈⭐