Compress, inspect without decompressing, then restore

Answer

gzip -9 access.log gzip -l access.log.gz zcat access.log.gz | head -3 gunzip access.log.gz

gzip -9 is maximum compression and deletes the original. -l reports the ratio. zcat sends the contents to standard output without touching the archive, so it pipes.

S&K 3e ch7 §7.2, §7.8-7.9