2008/3/21, Lyman :

Roman Kyrylych 写道:

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2008/3/21, Lyman :

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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".

/etc/lsb-release is defined in LSB, maybe there are simpler ways to get distro name on LSB compliant system, I don't know.

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.

Ok, I'll explain it in another way: /etc/issue is intended to be customized by user, thus software should *not* rely on it to get a distro name. /etc/distroname-release was invented exactly to solve this issue. If developers of screenlets wanted to make their life easier by writing less lines of code and relying on /etc/issue to have a distroname as first word/line - that's clearly a bug (or let's say "wrong solution") in their code. We will not "fix" it by changing our /etc/issue. BTW, removing those "invisible" chars at the beginning makes the text appear on screen without cleaning it first, so you'll see the rest of daemons loading output.

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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.

See http://virtualbox.org/browser/trunk/src/VBox/Installer/linux/VBoxSysInfo.sh Notice that all distros except Ubuntu use /etc/distroname-release even those that are LSB-compliant (I believe at least Fedora is). -- Roman Kyrylych (Роман Кирилич)

Roman Kyrylych 写道:

2008/3/21, Lyman :

...

Roman Kyrylych 写道:

...

2008/3/21, Lyman :

...

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".

/etc/lsb-release is defined in LSB, maybe there are simpler ways to get distro name on LSB compliant system, I don't know.

...

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.

Ok, I'll explain it in another way: /etc/issue is intended to be customized by user, thus software should *not* rely on it to get a distro name. You are right. I feel so sorry for replying last mail without taking a look at manpage of /etc/issue first.

/etc/distroname-release was invented exactly to solve this issue.

If developers of screenlets wanted to make their life easier by writing less lines of code and relying on /etc/issue to have a distroname as first word/line - that's clearly a bug (or let's say "wrong solution") in their code. Though I don't think the invention is simple enough, this is the reality. Thank you very much for your patience :)

We will not "fix" it by changing our /etc/issue. BTW, removing those "invisible" chars at the beginning makes the text appear on screen without cleaning it first, so you'll see the rest of daemons loading output.

...

...

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.

See http://virtualbox.org/browser/trunk/src/VBox/Installer/linux/VBoxSysInfo.sh Notice that all distros except Ubuntu use /etc/distroname-release even those that are LSB-compliant (I believe at least Fedora is).