Ruud H.G. van Tol wrote:
See also sed1line.txt:
http://sed.sourceforge.net/sed1line.txt
http://www.student.northpark.edu/pemente/sed/sed1line.txt
Eek! If you only knew what a lousy neighborhood that place is in ...
# delete all CONSECUTIVE blank lines from file except the first; also
# deletes all blank lines from top and end of file (emulates "cat -s")
sed '/./,/^$/!d' # method 1, allows 0 blanks at top, 1 at EOF
sed '/^$/N;/\n$/D' # method 2, allows 1 blank at top, 0 at EOF
Any sed code with a semicolon is not a proper one-liner, as some seds
don't grok that use of the semicolon and require two lines or two -e
options.
My experiences with cat -s are that it keeps one blank line (if there
are one or more there to start) at the top and likewise one (if there
are one or more there to start) at the bottomm, like this:
sed -e /./,/^$/b -e 1!d # semicolon form doesn't work
Getting sed to trim off all blank lines from the top and the bottom
requires some tangling with N and D and maybe P, so I can't write it off
the top of my head in Mozilla's editor; I'd need to use vi and do some
testing. However, a combination of the two above ought to work, I expect:
sed '/./,$ !d;/^$/N;/\n$/D'
if not
sed '/./,/^$/!d;/^$/N;/\n$/D'
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