Parsing version number of Linux distro to PHP variable

Question

I am trying to display the version number of a Linux distro on a web page. The distro is DietPi. The version number is stored in /DietPi/dietpi/.version and looks like this;

G_DIETPI_VERSION_CORE=7
G_DIETPI_VERSION_SUB=3
G_DIETPI_VERSION_RC=2
G_GITBRANCH='master'
G_GITOWNER='MichaIng'

This is what I have experimented with so far, which I've put together from examples I have found on SO.

<?php system("cat /DietPi/dietpi/.version  | cut -f2 -d'=' | sed 's/[^0-9]*//g' ") ;?>

This works but there are spaces between the digits thus 7 3 2 and I need to add periods so it looks like this 7.3.2

I suspect the above is probably not the most efficient way of doing this. I'd welcome help on inserting the periods or ideas on simpler methods that would work for me.

mario · Accepted Answer · 2021-07-03 21:02:34Z

1

The laziest option would be parse_ini_file and extract. (The usual caveat: do not use with arbitrary input. Seems perfectly reasonable in this case.)

extract(parse_ini_file("/DietPi/dietpi/.version"));

Then you have all entries available as vars for string concatenation right away:

echo "$G_DIETPI_VERSION_CORE.$G_DIETPI_VERSION_SUB.$G_DIETPI_VERSION_RC";

If there are e.g. stray carriage returns, then applying trim might still be necessary. - Do an array_map("trim", …) before the extract().
Typically parse_ini would already strip off trailing whitespace however.

answered Jul 3, 2021 at 21:02

mario

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hakre · Accepted Answer · 2021-07-03 21:16:01Z

@mario did beat me to it, but I had the same idea, this is my suggestion:

$ver = parse_ini_file('/DietPi/dietpi/.version');

$full = sprintf('%d.%d.%d', $ver['G_DIETPI_VERSION_CORE'], $ver['G_DIETPI_VERSION_SUB'], $ver['G_DIETPI_VERSION_RC']);

var_dump($full); // string(5) "7.3.2"

uses an array instead of extract
sprintf to normalize the string to integer values

There is a shortcut that can be taken in this case as those are the first three values in that file:

$ver = parse_ini_file('/DietPi/dietpi/.version');

$full = vsprintf('%d.%d.%d', $ver); // string(5) "7.3.2"

your mileage my vary, its basically the same, I think the main benefit is using parse_ini_file over system.

$full = vsprintf('%d.%d.%d', parse_ini_file('/DietPi/dietpi/.version'));
// string(5) "7.3.2"

(you may want to throw exceptions on warnings with this last variant to at least deal with problems getting the version number)

Pedro Rodrigues · Accepted Answer · 2021-07-03 20:51:59Z

0

A simple way to do it, using what you have done already, is to just replace the spaces with dots. You can use str_replace for that.

answered Jul 3, 2021 at 20:51

Pedro Rodrigues

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Alex Howansky · Accepted Answer · 2021-07-03 23:35:34Z

0

I believe DietPi already sources these values to your environment. If that's the case, you can skip the file read/parse and just pull directly out of $_ENV. (I'm not 100% sure about this, but it'll be a quick test for you at least.)

$version = sprintf(
    '%s.%s.%s',
    $_ENV['G_DIETPI_VERSION_CORE'],
    $_ENV['G_DIETPI_VERSION_SUB'],
    $_ENV['G_DIETPI_VERSION_RC']
);

answered Jul 3, 2021 at 23:35

Alex Howansky

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2 Comments

Graham Bentley Over a year ago

You are right, it does. Thanks for this and all the other suggestions :)

Graham Bentley Over a year ago

I had tried something like this originally but couldn't get it to work, all I got was two dots .. as the output? If I could debug this I think its the neater solution as some of work is already done.

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