final-newline

What it catches#

File with line breaks does not end with one.

A file that has more than one line but does not end with a line break. It is a note, offered so its safe fix can be applied with the others; no agent misreads the file because of it. With --format github notes are not annotated unless you pass --annotate-notes.

Why it matters#

POSIX defines a line as ending with a newline. Text appended later with echo >> or by an agent joins the last line instead of starting a new one.

$ tail -c 20 CLAUDE.md | od -c | tail -2
... u   s   e       p   n   p   m   .

$ tail -c 1 CLAUDE.md | od -c
0000000  \n

How to fix#

Add a line break at the end, using the same line ending as the rest of the file. asitis lint --fix-preview=safe prints that diff. Most editors have an "insert final newline" setting.

asitis can make this edit for you. asitis lint --fix-preview prints a unified diff that git apply accepts, and the suggest_fixes MCP tool returns the same diff; nothing is written to disk by either. The fix for this rule is marked safe: it does not change what the file says.

Suppress or configure#

For one finding, put a comment on the line above it. The reason after -- is optional but worth writing:

<!-- asitis-disable-next-line final-newline -- why this one is fine -->

For a whole file:

<!-- asitis-disable-file final-newline -- why this file is an exception -->

For every file, turn it off or change its severity in .asitisrc.json:

{ "rules": { "final-newline": "off" } }

A .asitisrc.json overrides entry limits a change to some paths, and a baseline (asitis lint --format json --write-baseline) accepts today's findings so only new ones fail the build.

Source#

pubs.opengroup.org, read on 14 October 2026.