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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.

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GETHUGEPAGESIZES(3)					     Library Functions Manual					       GETHUGEPAGESIZES(3)

NAME
gethugepagesizes - Get the system supported huge page sizes SYNOPSIS
#include <hugetlbfs.h> int gethugepagesizes(long pagesizes[], int n_elem); DESCRIPTION
The gethugepagesizes() function returns either the number of system supported huge page sizes or the sizes themselves. If pagesizes is NULL and n_elem is 0, then the number of huge pages the system supports is returned. Otherwise, pagesizes is filled with at most n_elem page sizes. RETURN VALUE
On success, either the number of huge page sizes supported by the system or the number of huge page sizes stored in pagesizes is returned. On failure, -1 is returned and errno is set appropriately. ERRORS
EINVAL n_elem is less than zero or n_elem is greater than zero and pagesizes is NULL. Also see opendir(3) for other possible values for errno. This error occurs when the sysfs directory exists but cannot be opened. NOTES
This call will return all huge page sizes as reported by the kernel. Not all of these sizes may be usable by the programmer since mount points may not be available for all sizes. To test whether a size will be usable by libhugetlbfs, hugetlbfs_find_path_for_size() can be called on a specific size to see if a mount point is configured. SEE ALSO
oprofile(1), opendir(3), hugetlbfs_find_path_for_size(3), libhugetlbfs(7) AUTHORS
libhugetlbfs was written by various people on the libhugetlbfs-devel mailing list. October 10, 2008 GETHUGEPAGESIZES(3)
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