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Full Discussion: File comparison of huge files
Top Forums UNIX for Dummies Questions & Answers File comparison of huge files Post 302588084 by Corona688 on Friday 6th of January 2012 04:15:32 PM
Old 01-06-2012
Quote:
Originally Posted by kaaliakahn
Thanks ctsgnb.


Could you please explain why do you need to sort?
It's the simplest and most reliable way to tell whether a line's a duplicate or not. sort is actually pretty sophisticated, capable of handling extremely huge files without bogging down. Once it's done so, any duplicate lines will show up all in a row, letting you use uniq to get rid of them.
Quote:
Thirdly please explain why use mknod?
He's actually making a named pipe. On many systems you can just use mkfifo for that.

A named pipe lets you do this:

Code:
mkfifo fifo
cat file > fifo &
cat fifo # the first cat writes to the fifo, the second cat reads from it.
# This is effectively cat file | cat.
# Named pipes can be a handy way to join together programs which
# read from filenames and can't easily handle stdin/stdout communication.

This User Gave Thanks to Corona688 For This Post:
kaaliakahn
 

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LEARN ABOUT REDHAT

cat

CAT(1)									FSF								    CAT(1)

NAME

       cat - concatenate files and print on the standard output

SYNOPSIS

       cat [OPTION] [FILE]...

DESCRIPTION

       Concatenate FILE(s), or standard input, to standard output.

       -A, --show-all
	      equivalent to -vET

       -b, --number-nonblank
	      number nonblank output lines

       -e     equivalent to -vE

       -E, --show-ends
	      display $ at end of each line

       -n, --number
	      number all output lines

       -s, --squeeze-blank
	      never more than one single blank line

       -t     equivalent to -vT

       -T, --show-tabs
	      display TAB characters as ^I

       -u     (ignored)

       -v, --show-nonprinting
	      use ^ and M- notation, except for LFD and TAB

       --help display this help and exit

       --version
	      output version information and exit

       With no FILE, or when FILE is -, read standard input.

AUTHOR

       Written by Torbjorn Granlund and Richard M. Stallman.

REPORTING BUGS

       Report bugs to <bug-coreutils@gnu.org>.

COPYRIGHT

       Copyright (C) 2002 Free Software Foundation, Inc.
       This is free software; see the source for copying conditions.  There is NO warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICU-
       LAR PURPOSE.

SEE ALSO

       The full documentation for cat is maintained as a Texinfo manual.  If the info and cat programs are properly installed at  your	site,  the
       command

	      info cat

       should give you access to the complete manual.

cat (coreutils) 4.5.3						   February 2003							    CAT(1)
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