[aur-general] Why /etc/issue starts with invisible chars?

[Lyman]

Roman Kyrylych 写道:
> 2008/3/21, Lyman <lymanrb at gmail.com>:
>> Hi, all
>>
>>  I found this issue when I was trying Sysmonitor in the package
>>  screenlets because Sysmonitor can not show my distribution name correctly.
>>
>>  At the beginning I thought that it was a bug of screenlets, however,
>>  when I dug into its source code, I realized that it could be a "bug"
>>  introduced by Archlinux because the /etc/issue starts with some
>>  invisible chars.
>>
>>  Here's the hexdump of /etc/issue in Archlinux. It is obviously that the
>>  first line in this file is not the distribution name.
>>
>>  00000000  1b 5b 48 1b 5b 32 4a 0a  41 72 63 68 20 4c 69 6e
>>  |.[H.[2J.Arch Lin|
>>  00000010  75 78 20 28 43 6f 72 65  20 44 75 6d 70 29 20 20  |ux (Core
>>  Dump)  |
>>  00000020  5c 72 20 20 28 5c 6e 29  20 28 5c 6c 29 0a 0a     |\r  (\n)
>>  (\l)..|
>>
>>  I've checked other two distribution, CentOS and Ubuntu (that's all I
>>  have at the moment), both of them presents the their name in the first line.
>>
>>  I guess most of the applications just use the first line in /etc/issue
>>  as distribution name (so do screenlets). I think Archlinux should comply
>>  with "Rule of Least Surprise" on this issue. If the invisible chars are
>>  just for clearing screen, we can do that from the second line.
> 
> We already do. :-)
> /etc/issue is *not* a way to check for distribution name. Apps that do
> this are wrong.
> Most distros have /etc/distroname-release files as well (that contain
> the version, that's why it's empty in Arch).
Things seem not that simple, though. On CentOS, I found 
/etc/redhat-release. On Ubuntu, there's no /etc/ubuntu-release but only 
/etc/lsb-release. Unfortunately, the latter one is a formatted text file 
and applications can not depend on it by a rule as simple as "the first 
line".

Considering there's so many distributions in Linux world, it seems quite 
confusing for developers to do something absolutely "correct", right?

I will forward these information to the developers of screenlets. 
However, I still insisted on suggesting changing /etc/issue to a 
"normal" one because I didn't see any advantages of inserting invisible 
chars in the first line. By doing just a little "favor", it will makes 
Archlinux more "compatible" && friendly to both developers and end 
users, I think.

> Good written apps check for *existence* of /etc/arch-release file to
> know whether they are on Arch Linux.
> See virtualbox's installer for example how a check for distribution
> should be made.
> 
Can you please point out which file is the installer? There's so many 
files in the package virtualbox-ose and I failed to find an "obvious" 
installer. Thanks.

lyman