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From: schaefer@ogcvax.UUCP (Barton E. Schaefer)
Newsgroups: comp.unix.questions
Subject: Re: Invisible Ascii with VI
Message-ID: <1437@ogcvax.UUCP>
Date: Fri, 2-Oct-87 13:44:25 EDT
Article-I.D.: ogcvax.1437
Posted: Fri Oct  2 13:44:25 1987
Date-Received: Thu, 8-Oct-87 07:26:47 EDT
References: <258@unx1.UUCP> <hplsdlw.630001>
Reply-To: schaefer@ogcvax.UUCP (Barton E. Schaefer)
Organization: Oregon Graduate Center, Beaverton, OR
Lines: 40

In article <hplsdlw.630001> was@hplsdlw.HP.COM (William A. Stubblebine) writes:
}> / hplsdlw:comp.unix.questions / andy@unx1.UUCP (Andy Clews):
}> Does anyone out there know if it's possible to insert/search/replace
}> non-printing ascii characters?
}> Specifically: I sometimes get files from a net source that have an "extra"
}> CR tacked on the end of the line ...
}[ Some explanation of how to do this deleted ]
}
}Unfortunately, many versions if ex/vi have a bug in handling ^M as a
}replacement pattern via ex while in visual mode.  That is, typing
}    :s/;/\^M/g
}to change 
}    hello;goodbye
}into
}    hello
}    goodbye
}while in visual mode doesn't work.  The ^M isn't interpreted as the
}replacement pattern, it just terminates the command.

The way to get around problems like this is to use double ^V characters; that
is, you type

	:s/;/^V^V^V^M/g^M

(you use the RETURN key instead of CTRL-M) which echoes as

	:s/;/^V^M/g

The first ^V assures that the second ^V will be passed on to the ex substitute
command after vi-interface parsing; the third ^V escapes the ^M so it isn't
interpreted as the end of the command.  The ex substitute command then sees
the ^V^M sequence and interprets it as a literal ^M.

I don't know if this works on versions that interpret a backslash-escaped ^M
"correctly", but it works for me (UNIX 4.3 BSD).
-- 
Bart Schaefer			CSNET:	schaefer@Oregon-Grad
				UUCP:	...{tektronix,verdix}!ogcvax!schaefer
"This area is like heaven, and they want to turn it into California."
		-- Joseph Cook, Amish farmer, protesting highway construction