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Full Discussion: Want to remove all lines but not latest 50 lines from a file
Top Forums UNIX for Dummies Questions & Answers Want to remove all lines but not latest 50 lines from a file Post 302868217 by alister on Saturday 26th of October 2013 03:24:17 PM
Old 10-26-2013
In-place move to the top of the file of the final 5 lines without using any variables or temp files:
Code:
dd if=/dev/null of=fname bs=1 seek=$(tail -n5 fname | tee >(wc -c) 1<>fname)

Note: The process substitution implementations I've seen require either /dev/fd or named pipes. If /dev/fd isn't available, and if the shell cannot create the fifo in its usual temp dir, the shell may need to be informed of a suitable alternative location.

Regards,
Alister
Last edited by alister; 10-26-2013 at 06:26 PM.. Reason: Corrected text to match tail's five line count
These 3 Users Gave Thanks to alister For This Post:
balajesuri drl Scrutinizer
 

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LEARN ABOUT CENTOS

zip_name_locate

ZIP_NAME_LOCATE(3)					     Library Functions Manual						ZIP_NAME_LOCATE(3)

NAME

       zip_name_locate - get index of file by name

LIBRARY

       libzip (-lzip)

SYNOPSIS

       #include <zip.h>

       int zip_name_locate(struct zip *archive, const char *fname, int flags);

DESCRIPTION

       The  zip_name_locate  function returns the index of the file named fname in archive.  If archive does not contain a file with that name, -1
       is returned.  The are specified by or'ing the following values, or 0 for none of them.

	      ZIP_FL_NOCASE  Ignore case distinctions.

	      ZIP_FL_NODIR   Ignore directory part of file name in archive.

RETURN VALUES

       zip_name_locate returns the index of the file named fname or -1, if archive does not contain an entry of that name.

ERRORS

       The zip_name_locate function fails and sets the error information to ZIP_ER_NOENT if no entry of the name fname is found  in  the  archive.
       If one of the arguments is invalid, the error information is set to ZIP_ER_INVAL.

SEE ALSO

       libzip(3), zip_get_name(3)

AUTHORS

       Dieter Baron <dillo@giga.or.at> and Thomas Klausner <tk@giga.or.at>

NiH								  October 4, 2006						ZIP_NAME_LOCATE(3)
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