docs: document "got incomplete line before first line" warning in in_tail - #655
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Add an FAQ entry explaining that in_tail emits this warning only in multiline mode (format_firstline), when it reads a continuation line before matching a first line. List the common causes: reading that starts in the middle of a record (e.g. after rotation or with read_from_head false), a format_firstline that does not match the real first line, and a single <parse> shared by files of different formats through a path glob. Note that these lines are dropped unless emit_unmatched_lines is set to true. Signed-off-by: Shizuo Fujita <fujita@clear-code.com>
Co-authored-by: Kentaro Hayashi <kenhys@gmail.com> Signed-off-by: Shizuo Fujita <fujita@clear-code.com>
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What
Add an FAQ entry to
input/tail.mdthat documents thegot incomplete line before first linewarning emitted byin_tail.Why
Reported in #466. The warning is emitted by
in_tailin multiline mode, but it was not documented anywhere, so users had no way to tell what it meant or whether data was being lost.Note
#466 also points out that the
formatNparameter table on themultilineparser page does not match the implementation. That part is left for a separate follow-up PR, so this PR intentionally does not close #466.Refs #466