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Top Forums Shell Programming and Scripting Detail on For loop for multiple file input and bash variable usage Post 302781353 by Don Cragun on Saturday 16th of March 2013 09:24:56 AM
Old 03-16-2013
I don't understand what you're asking about fortran code, but getting sets of 3 files in sorted order in the shell is not hard. This doesn't do anything very useful, but may be a suitable example to show you what needs to be done to meet your requirements:
Code:
#!/bin/ksh
ls *.txt|sort -t"_" -k2n,2|while read f1 && read f2 && read f3
do      echo processing $f1, $f2, and $f3
done

Note that this won't work if any of your *.txt filenames contain whitespace characters, and will silently ignore the last one or two *.txt files if the number of *.txt files is not an integral multiple of 3. In a directory containing the files:
Code:
ABC_6.txt
B.txt
DEF_5.txt
GHI_7.txt
a.txt
abc_123.txt
bcd_987.txt
cde_456.txt
tester
z.txt

this script produces the output:
Code:
processing B.txt, a.txt, and z.txt
processing DEF_5.txt, ABC_6.txt, and GHI_7.txt
processing abc_123.txt, cde_456.txt, and bcd_987.txt

This User Gave Thanks to Don Cragun For This Post:
 

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bup-margin(1)						      General Commands Manual						     bup-margin(1)

NAME
bup-margin - figure out your deduplication safety margin SYNOPSIS
bup margin [options...] DESCRIPTION
bup margin iterates through all objects in your bup repository, calculating the largest number of prefix bits shared between any two entries. This number, n, identifies the longest subset of SHA-1 you could use and still encounter a collision between your object ids. For example, one system that was tested had a collection of 11 million objects (70 GB), and bup margin returned 45. That means a 46-bit hash would be sufficient to avoid all collisions among that set of objects; each object in that repository could be uniquely identified by its first 46 bits. The number of bits needed seems to increase by about 1 or 2 for every doubling of the number of objects. Since SHA-1 hashes have 160 bits, that leaves 115 bits of margin. Of course, because SHA-1 hashes are essentially random, it's theoretically possible to use many more bits with far fewer objects. If you're paranoid about the possibility of SHA-1 collisions, you can monitor your repository by running bup margin occasionally to see if you're getting dangerously close to 160 bits. OPTIONS
--predict Guess the offset into each index file where a particular object will appear, and report the maximum deviation of the correct answer from the guess. This is potentially useful for tuning an interpolation search algorithm. --ignore-midx don't use .midx files, use only .idx files. This is only really useful when used with --predict. EXAMPLE
$ bup margin Reading indexes: 100.00% (1612581/1612581), done. 40 40 matching prefix bits 1.94 bits per doubling 120 bits (61.86 doublings) remaining 4.19338e+18 times larger is possible Everyone on earth could have 625878182 data sets like yours, all in one repository, and we would expect 1 object collision. $ bup margin --predict PackIdxList: using 1 index. Reading indexes: 100.00% (1612581/1612581), done. 915 of 1612581 (0.057%) SEE ALSO
bup-midx(1), bup-save(1) BUP
Part of the bup(1) suite. AUTHORS
Avery Pennarun <apenwarr@gmail.com>. Bup unknown- bup-margin(1)
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