Files test How to recover a specific variable Post: 302981885

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Top Forums Shell Programming and Scripting Files test How to recover a specific variable Post 302981885 by rovf on Wednesday 21st of September 2016 02:58:15 AM

09-21-2016

Registered User

As for displaying the full path, you have two choices: If you know that the file names are always relative pathes, the easiest is to prepend $PWD/. If this is not the case, or if you want to have the path "cleaned up" by not containing .. elements, you need to convert it to an absolute path explicitly. Google for "how to convert a relative path to an absolute path".

Aside from this, the logic of your script is flawed. You obviously want to treat each file separately, i.e. create for each file some information, whether it is missing or not. You have (at least) two choices to achieve this:

The first ist to output the desired information INSIDE the if-block where you detect that the file is missing. The second one - if, for whatever reason, you want to keep problem DETECTION and problem REPORTING separate, I suggest a completely differnt approach:

Either use two arrays (one containing all the file names, and one containing a code for the problem occuring with each corresponding file, for instance "missing" or "ok"), or alternatively use only one associative array, where the key is the file name and the value is "missing" or "ok".

---------- Post updated at 08:58 AM ---------- Previous update was at 08:50 AM ----------

I just noticed - by re-reading your initial post - that you never indicated which shell you are using, so some of the suggestions (such as associative arrays) I gave might not work in your shell.

Hence, the first step would be that you decide on a certain shell language, before we can discuss, how exactly a problem can be solved.

Common language choices are:

- POSIX shell (most unconvenient to program, but maximum compatibility - this is often used by system administrators who have to manage a network of different Unix flavours or different shell versions)

- bash (chances are highest that, if you ask a colleague, s/he will know it)

- Zsh (IMO most convenient for shell programming)

- ksh (Many people like it; I can't comment on it, because of lack of experience)

I use for most of my shell programming Zsh, because it is really made for programmers, but bash is also a very popular choice.

rovf

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LEARN ABOUT DEBIAN

bup-margin

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)