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ConCATenating binaries but excluding last bytes from each file
Post 302877652 by grolido on Monday 2nd of December 2013 06:49:02 PM
12-02-2013
ConCATenating binaries but excluding last bytes from each file
Hi there, shameful Linux Newbie here 
I was wondering if you could help with my problem...
I have plenty of files I'd like to concatenate. I know how to basically use cat command but that won't be enough from what I need : excluding the last xx bytes from files before assembling since there's some redundancy
the interesting part is the xx bytes to remove is determined by the filename themselves, ie
file 1 is named something like 0-54548
file 2 is named something like 54475-648459
file 3 is named 648345-1269494
etc
so for file 1 I would have to drop bytes between 54475 till the end before joining file 2. etc
it would be easier if it was always the exact same bytes value to remove , alas there are some variations, so it must be calculated from filenames.
I feel like it's possible to script something with not much lines within a loop, but my unix knowledge is way too rudimentary for now ^^
I also read about dd command which could probably be of some help to generate the files without the unwanted part, now I'm a bit clueless about extracting character chains from filenames, turning into numeric values, doing the maths and use this dd or whatever else command so I can assemble the resulting files...
I was wondering if you could help with my problem...
I have plenty of files I'd like to concatenate. I know how to basically use cat command but that won't be enough from what I need : excluding the last xx bytes from files before assembling since there's some redundancy
the interesting part is the xx bytes to remove is determined by the filename themselves, ie
file 1 is named something like 0-54548
file 2 is named something like 54475-648459
file 3 is named 648345-1269494
etc
so for file 1 I would have to drop bytes between 54475 till the end before joining file 2. etc
it would be easier if it was always the exact same bytes value to remove , alas there are some variations, so it must be calculated from filenames.
I feel like it's possible to script something with not much lines within a loop, but my unix knowledge is way too rudimentary for now ^^
I also read about dd command which could probably be of some help to generate the files without the unwanted part, now I'm a bit clueless about extracting character chains from filenames, turning into numeric values, doing the maths and use this dd or whatever else command so I can assemble the resulting files...
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LEARN ABOUT CENTOS
cat
CAT(1) User Commands 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 nonempty output lines, overrides -n -e equivalent to -vE -E, --show-ends display $ at end of each line -n, --number number all output lines -s, --squeeze-blank suppress repeated empty output lines -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. EXAMPLES
cat f - g Output f's contents, then standard input, then g's contents. cat Copy standard input to standard output. GNU coreutils online help: <http://www.gnu.org/software/coreutils/> Report cat translation bugs to <http://translationproject.org/team/> AUTHOR
Written by Torbjorn Granlund and Richard M. Stallman. COPYRIGHT
Copyright (C) 2013 Free Software Foundation, Inc. License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>. This is free software: you are free to change and redistribute it. There is NO WARRANTY, to the extent permitted by law. SEE ALSO
tac(1) 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 coreutils 'cat invocation' should give you access to the complete manual. GNU coreutils 8.22 June 2014 CAT(1)