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Full Discussion: SED command for read and write to different files
Top Forums Shell Programming and Scripting SED command for read and write to different files Post 302255779 by bakunin on Friday 7th of November 2008 05:19:05 AM
Old 11-07-2008
Quote:
Originally Posted by gaurav_1711
i tried..

sed "s/^/prefix/;s/\n/sufix/" oldfile > newfile

but it is only adds the prefix...
The reason is that there is no "\n" at the end of the line as far as sed is concerned. There is a far more easy device to match line ends or line beginnings, which you have already seen used here:

"^" at the beginning of a regex means "line beginning". "x" finds any x, "^x" finds only an "x" on first position of the line.

"$" at the end of a regex means "line end". "x$" would match only a line ending with "x".

There is another metacharacter you have seen used here: "&" in a replacement string this means "everything that has been matched by the regex". Example:

echo "xxxabcxxx" | sed 's/abc/y&y/' ==> will give "xxxyabcyxxx"
echo "xxxabcxxx" | sed 's/ab/y&y/' ==> will give "xxxyabycxxx"

You should now be able to create a correct sed script yourself. In fact you have two ways of doing it shown here.

I hope this helps.

bakunin
 

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LEARN ABOUT SUNOS

diffmk

diffmk(1)							   User Commands							 diffmk(1)

NAME

       diffmk - mark differences between versions of a troff input file

SYNOPSIS

       diffmk oldfile newfile markedfile

DESCRIPTION

       diffmk  compares  two versions of a file and creates a third version that includes "change mark" (.mc) commands for nroff(1) and  troff(1).
       oldfile and newfile are the old and new versions of the file. diffmk generates markedfile, which,  contains  the  text  from  newfile  with
       troff(1) "change mark" requests (.mc) inserted where  newfile differs from  oldfile. When markedfile is formatted, changed or inserted text
       is shown by  | at the right margin of each line. The position of deleted text is shown by a single *.

USAGE

       See largefile(5) for the description of the behavior of diffmk when encountering files greater than or equal to 2 Gbyte ( 2**31 bytes).

EXAMPLES

       Example 1: An example of the diffmk command.

       diffmk can also be used in conjunction with the proper  troff requests to produce program listings with marked changes.	In  the  following
       command line:

       example% diffmk old.c new.c marked.c ; nroff reqs marked.c | pr

       the file reqs contains the following troff requests:

       .pl 1
       .ll 77
       .nf
       .eo
       .nh

       which eliminate page breaks, adjust the line length, set no-fill mode, ignore escape characters, and turn off hyphenation, respectively.

       If the characters  | and * are inappropriate, you might run  markedfile through	sed(1) to globally change them.

ATTRIBUTES

       See attributes(5) for descriptions of the following attributes:

       +-----------------------------+-----------------------------+
       |      ATTRIBUTE TYPE	     |	    ATTRIBUTE VALUE	   |
       +-----------------------------+-----------------------------+
       |Availability		     |SUNWdoc			   |
       +-----------------------------+-----------------------------+

SEE ALSO

       diff(1), nroff(1), sed(1), troff(1), attributes(5), largefile(5)

BUGS

       Aesthetic  considerations  may  dictate	manual	adjustment of some output. File differences involving only formatting requests may produce
       undesirable output, that is, replacing .sp by .sp 2 will produce a "change mark" on the preceding or following line of output.

SunOS 5.10							    14 Sep 1992 							 diffmk(1)
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