02-18-2008
omitting lines from file A that are in file B
I've got file A with (say) 1M lines in it ... ascii text, space delimited ...
I've got file B with (say) 10M lines in it ... same structure.
I want to remove any lines from A that appear (identically) in B and print the remaining (say) 900K lines. (And I want to do it in zero time of course!)
Best I've come up with so far is somehow marking the lines in A, then doing a sort and applying an awk script to the result so that the marked lines are only printed if the following (or previous) line isn't "identical" except for the mark.
But after 1000 years of shell programming I've GOT to believe I'm missing an easier/faster solution ... I'm using bash and cygwin tools - and compiling is not an option.
ADVthanksANCE for your help!
=Gneen
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LEARN ABOUT CENTOS
colcrt
COLCRT(1) User Commands COLCRT(1)
NAME
colcrt - filter nroff output for CRT previewing
SYNOPSIS
colcrt [options] [file ...]
DESCRIPTION
colcrt provides virtual half-line and reverse line feed sequences for terminals without such capability, and on which overstriking is
destructive. Half-line characters and underlining (changed to dashing `-') are placed on new lines in between the normal output lines.
OPTIONS
-, --no-underlining
Suppress all underlining. This option is especially useful for previewing allboxed tables from tbl(1).
-2, --half-lines
Causes all half-lines to be printed, effectively double spacing the output. Normally, a minimal space output format is used which
will suppress empty lines. The program never suppresses two consecutive empty lines, however. The -2 option is useful for sending
output to the line printer when the output contains superscripts and subscripts which would otherwise be invisible.
-V, --version
Output version information and exit.
-h, --help
Output help and exit.
EXAMPLES
A typical use of colcrt would be
tbl exum2.n | nroff -ms | colcrt - | more
SEE ALSO
nroff(1), troff(1), col(1), more(1), ul(1)
BUGS
Should fold underlines onto blanks even with the '-' option so that a true underline character would show.
Can't back up more than 102 lines.
General overstriking is lost; as a special case '|' overstruck with '-' or underline becomes '+'.
Lines are trimmed to 132 characters.
Some provision should be made for processing superscripts and subscripts in documents which are already double-spaced.
HISTORY
The colcrt command appeared in 3.0BSD.
AVAILABILITY
The colcrt command is part of the util-linux package and is available from Linux Kernel Archive <ftp://ftp.kernel.org/pub/linux/utils/util-
linux/>.
util-linux September 2011 COLCRT(1)