.tip

Mar 10, 2026 · one of the small things

comm compares two sorted lists in one pass

Which ids are in file A and not in B is a question comm answers directly, three columns: only in A, only in B, in both.

comm -23 <(sort a.txt) <(sort b.txt)   # only in a
comm -12 <(sort a.txt) <(sort b.txt)   # in both

Both inputs must be sorted. The process substitution sorts them inline.

shell

~/tips/today — 2026-09-04

~cat tips/today

Session cookies: HttpOnly, Secure, SameSite=Lax

securityhttp

Three attributes, each closing a class of attack. HttpOnly keeps scripts from reading it. Secure keeps it off plain HTTP. SameSite=Lax stops it being sent on cross-site POSTs, which is most CSRF.

Set-Cookie: session=...; HttpOnly; Secure; SameSite=Lax; Path=/; Max-Age=1209600

Strict breaks arriving from an external link while logged in. Lax is the default worth keeping.

↵ open y yesterday l ls /tips

esc close