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Full Discussion: SED command explanation
Top Forums UNIX for Dummies Questions & Answers SED command explanation Post 302433436 by Phil Stracchino on Tuesday 29th of June 2010 04:52:27 PM
Old 06-29-2010
In short, what this will do is the following: Given an arbitrary string containing one or more characters that are not | followed by a |, take everything after that | character and move it to the front of that whole pattern. So, for example, it would turn 'foo|bar' into 'barfoo|', but '||foo|bar' would become '||barfoo|'. The first | is bypassed because it has nothing on its left; the second is skipped because it has only another | on its left. 'bar' is moved after the leading || characters because they are not part of the pattern matched.

(Whether this is what was actually intended is another question.)

As a side note, 's/\([^|][^|]*|\)\(.*\)/\2\1/' is equivalent to the simpler pattern 's/\([^|]+|\)\(.*\)/\2\1/'. [^|] is the set of all characters which are not |, so [^|]* matches any zero or more characters that are not |, while [^|]+ matches any one or more such characters, which makes [^|][^|]* functionally identical to [^|]+ within the regexp.

O'Reilly has a good book on regular expressions. It covers things like this and much more.
 

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LEARN ABOUT DEBIAN

fixnt

fixnt(1)							      Debian								  fixnt(1)

NAME

       fixnt - Filter for the Windows NT postscript printer driver.

SYNOPSIS

       fixnt < BADFILE.ps > GOODFILE.ps

DESCRIPTION

       The  Windows  NT  postscript  driver has a tendency to make broken postscript files, that are incompatible with psutils.  fixnt is a filter
       that fixes these problems, allowing the use of psnup(1).

       The filter takes the broken postscript file on stdin, and outputs a fixed postscript file on stdout.  It has no other form  for	invocation
       and takes no options on the command-line.

OPTIONS

       fixnt  takes no options.

BUGS

       fixnt does not check for NTPSOct94.  For a workaround, use a sed(1) command to replace 'NTPSOct94' with 'NTPSOct95', like so:
	      sed 's/NTPSOct94/NTPSOct95/g'
       This is particularly important for Windows NT 3.5 users.

AUTHOR

       fixnt   was   written   by   Holger   Bauer   <Holger.Bauer@topmail.de>,  Michael  Rath	<rath@itsm.uni-stuttgart.de>,  and  Akim  Demaille
       <demaille@inf.enst.fr>.

REPORTING BUGS

       Report bugs to the Authors, but avoid sending large postscript files.

       Patches are always welcome; send to <bauer@itsm.uni-stuttgart.de>.

SEE ALSO

       psnup(1), sed(1)

a2ps								   February 2003							  fixnt(1)
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