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Top Forums Shell Programming and Scripting perl/shell need help to remove duplicate lines from files Post 302483206 by DGPickett on Friday 24th of December 2010 10:47:16 AM
Old 12-24-2010
OK, A. the key is not the whole line, and B. duplicates across files are bad, two complications. Reporting the duplicate means a definition of the original, expecially for non-key data.
  • If the lines have identical keys and not identical payload (fields not keys), then will file name order and order in file pick a winner?
  • We need to survey all files for duplicate keys, then extract the unique and winners to load, and the losers to report. Think of them as two important products, not picking favorites. While most days there may be no duplicates, if one day there are tons, you still want it to blast through.
  • There are two approaches to dealing with duplicate filtering. You can save every key in an associative array (magic box that recalls by value, but may not be robust in speed and stability with huge volume) or you can sort in key, priority order (more traditional and quite robust if you have the disk space. Store just the last key, process the first of every key and log the others. Worked great on tape in 1960 with 16K or RAM! :-)
  • Tagging the duplicates by original file means adding the file name to every record, possible but a bit of a luxury if not needed.
 

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KEYCTL_UPDATE(3)					    Linux Key Management Calls						  KEYCTL_UPDATE(3)

NAME
keyctl_update - Update a key SYNOPSIS
#include <keyutils.h> long keyctl_update(key_serial_t key, const void *payload, size_t plen); DESCRIPTION
keyctl_update() updates the payload of a key if the key type permits it. The caller must have write permission on a key to be able update it. payload and plen specify the data for the new payload. payload may be NULL and plen may be zero if the key type permits that. The key type may reject the data if it's in the wrong format or in some other way invalid. RETURN VALUE
On success keyctl_update() returns 0. On error, the value -1 will be returned and errno will have been set to an appropriate error. ERRORS
ENOKEY The key specified is invalid. EKEYEXPIRED The key specified has expired. EKEYREVOKED The key specified had been revoked. EINVAL The payload data was invalid. ENOMEM Insufficient memory to store the new payload. EDQUOT The key quota for this user would be exceeded by increasing the size of the key to accommodate the new payload. EACCES The key exists, but is not writable by the calling process. EOPNOTSUPP The key type does not support the update operation on its keys. LINKING
This is a library function that can be found in libkeyutils. When linking, -lkeyutils should be specified to the linker. SEE ALSO
keyctl(1), add_key(2), keyctl(2), request_key(2), keyctl(3), request-key(8) Linux 4 May 2006 KEYCTL_UPDATE(3)
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