December 2002
Intermediate to advanced
1232 pages
56h 38m
English
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Comments
Comments provide you with the documentation necessary to maintain the configuration file. Because comments slow down sendmail by only a negligible amount, and only at startup, it is better to overcomment than to undercomment.
Blank
lines and lines that begin with a # character are
considered comments and are ignored. A blank line is one that
contains no characters at all (except for its terminating newline).
Indentation characters (spaces and tabs) are invisible and can turn
an apparently blank line into an empty-looking
line, which is not ignored:
# text ← a comment tabtext← a continuation line ← a blank line tab← an "empty-looking line"
Except for two special cases, pre-V8 comments occupy the entire line.
The two special cases are the R and
S configuration commands. The R
command is composed of three tab-separated fields, the third field
being a comment that does not require a leading #
character:
Rlhs rhs comment
The pre-V8.7 S command looks only for a number
following it and ignores everything else, so it can also be followed
by a comment:
S3 this is a comment
Prior to V8, no other commands allow comments to follow on the same line:
CWlocalhost mailhost # This won't work prior to V8
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O’Reilly covers everything we've got, with content to help us build a world-class technology community, upgrade the capabilities and competencies of our teams, and improve overall team performance as well as their engagement.Julian F.
I wanted to learn C and C++, but it didn't click for me until I picked up an O'Reilly book. When I went on the O’Reilly platform, I was astonished to find all the books there, plus live events and sandboxes so you could play around with the technology.Addison B.
I’ve been on the O’Reilly platform for more than eight years. I use a couple of learning platforms, but I'm on O'Reilly more than anybody else. When you're there, you start learning. I'm never disappointed.Amir M.
I'm always learning. So when I got on to O'Reilly, I was like a kid in a candy store. There are playlists. There are answers. There's on-demand training. It's worth its weight in gold, in terms of what it allows me to do.