How to reorder command line arguments in a script?

evo2 · 02-24-2023, 07:31 PM

Maybe I'm misinterpreting the question but my take is that there is some existing program called "compressor". It expects arguments as follows:

Code:

% compressor --help
USAGE: compressor <compression level> <inputfiles> <outputfile>

And OP wants a wrapper script, such as:

Code:

% compressor.sh --help
USAGE: compressor.sh <inputfiles> <outputfile> <compression level>

My post was an example of compressor.sh

Evo2.

michaelk · 02-24-2023, 07:39 PM

Ok, so we all have the same understanding.

pan64 · 02-25-2023, 01:24 AM

Quote:

Originally Posted by astrogeek

I have stayed out of this discussion waiting for someone to ask what that reason actually is, so this looks like a good point to ask it myself...

@OP: What, exactly, are you trying to accomplish by reordering those args? Please describe the intended use, including a description of the problem to be solved and how you think this will solve it.

I don't think there is a problem here. It is only about the order of the arguments. I think OP just wanted a different order, which is much more convenient for him/her. I totally agree with it, there is no logic behind that, so (in general) the expected order of the arguments (in most cases) are just strange, unusual. But actually this is how it was implemented. And you always have the possibility to add a wrapper to it.
I know we have conventions, we have similar programs, just that won't make it more convenient.

goumba · 06-12-2023, 05:45 PM

Quote:

Originally Posted by JASlinux

Imagine a file compression utility called compressor.

syntax: compressor [compression level] [archive name] [files to add]

On the command line I want to enter the compression level LAST.

example:

Code:

compressor newarchive.comp *.txt 9

How do I assign those variables in the correct order in Bourne?

Quote:

Originally Posted by astrogeek

@OP: What, exactly, are you trying to accomplish by reordering those args? Please describe the intended use, including a description of the problem to be solved and how you think this will solve it.

The question seems to me to be: "The scripts wants the arguments in a specific order. If the user enters them in the wrong order (in the example, compression level last instead of filename), how can I store the correct value in the associated variable?"

So, it seems the OP wants to be able to take the arguments in any order, but store the values properly. Simple loops and shift won't work here.

If I'm correct in my interpretation, OP, the only solution is using getopts as posted previously (or a homebrewed argument parser). It forces the user to specify which argument is which, and can do so in whatever order. You then handle it appropriately.

MadeInGermany · 06-13-2023, 03:48 AM

I gave the solution. (But evo2 must have misunderstood something, and the OP did not come back.)

Code:

% cat compressor.sh
#!/bin/sh
n=$#
while [ $((n-=1)) -gt 0 ]
do
  set -- "$@" "$1"
  shift
done
echo compressor "$@"
% chmod 755 compressor.sh
% touch a.txt b.txt
% ./compressor.sh newarchive.comp *.txt 9
compressor 9 newarchive.comp a.txt b.txt

This solves the requirement. Of course the echo is for demonstration and must be removed to really run the "compressor".

Quote:

Imagine a file compression utility called compressor.

syntax: compressor [compression level] [archive name] [files to add]

On the command line I want to enter the compression level LAST.

example:

compressor newarchive.comp *.txt 9

evo2 · 06-15-2023, 12:37 AM

Quote:

Originally Posted by MadeInGermany

I gave the solution. (But evo2 must have misunderstood something, and the OP did not come back.)

No. There are two different interpretations as to what was being asked. OP never clarified.

NevemTeve · 06-15-2023, 02:43 AM

Also '9' can be a perfectly valid filename.

dugan · 06-15-2023, 06:51 PM

Just make the change to "compressor" itself. It's open-source, isn't it?

bigearsbilly · 06-21-2023, 05:30 AM

Exactly astrogeek, why?

it seems like a waste of effort