Difference between pages "Package:Vim" and "Hostname"

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{{Ebuild
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==Introduction==
|Summary=Vim is an improved, vi-style text editor with many features.
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A hostname is a unique name created to identify a machine on a network. In computer networking, a hostname  is a label that is assigned to a device connected to a computer network and that is used to identify the device in various forms of electronic communication such as the World Wide Web, e-mail or Usenet. Hostnames may be simple names consisting of a single word or phrase, or they may be structured.
|CatPkg=app-editors/vim
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==Configuration==
|Maintainer=
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In Funtoo Linux <code>/etc/conf.d/hostname</code> is the only configuration file for setting a hostname. In OpenRC framework <code>/etc/conf.d/foo</code> is the configuration file for a corresponding Init script <code>/etc/init.d/foo</code>.  With the case of hostname, default value in <code>/etc/conf.d/hostname</code> is set to ''localhost'', means when system boots and OpenRC's <code>/etc/init.d/hostname</code> script started a hostname getting only ''localhost'' name.  How it looks?  In your shell promt this will look in following way, an example for root:
|Repository=Gentoo Portage Tree
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<console>
}}
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localhost ~ # ##i## Hello :)
== Introduction ==
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</console>
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Let's play a bit with a configuration. Open <code>/etc/conf.d/hostname</code> with your favorite editor and set a hostname of your choice.  Below, I will use a real examples  from one of my working test boxes.
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<console>
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localhost ~ # ##i## nano /etc/conf.d/hostname
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</console>
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Let's set it to hostname="oleg-stable.host.funtoo.org". Save the file and restart  a hostname service:
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<console>
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localhost ~ # ##i## service hostname restart
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</console>
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Now, let's examine our changes, after a restarting a hostname
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<console>
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oleg-stable ~ # ##i## Hello :)
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</console>
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== Diving deeper==
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Notice, that in above output we seeing a shortened hostname and not a FQDN (Fully Qualified Domain Name). Don't be frustrated. This is  how  default bash promt <code>PS1</code> set. To get nice promts, please, follow http://www.funtoo.org/Prompt_Magic
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Another way to test our settings is using a '''hostname''' command. Here we will show only  some of it's features. Let's try to execute '''hostname''' command:
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<console>
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oleg-stable ~ # ##i## hostname
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oleg-stable.host.funtoo.org
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</console>
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Now we see our fully qualified domain name hostname just how we configured it in <code>/etc/conf.d/hostname</code> in above paragraph. To get a short hostname we need to set '''-s ''' (short) argument to hostname command.
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<console>
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oleg-stable ~ # ##i## hostname -s
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oleg-stable
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</console>
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Good! Hostname offers more then just displaying a system host name but can also set one. Let's try:
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<console>
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oleg-stable ~ # ##i## hostname foo.bar.baz
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oleg-stable ~ # ##i## hostname
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foo.bar.baz
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</console>
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As you can see, we changed a hostname on-the-fly. This is not recommended way.
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{{fancywarning|Please, notice that using '''hostname''' command to configure will work temporary for a current session and will be reverted back to a value set in <code>/etc/conf.d/hostname</code> file with next system restart.}}
  
So you thought you could get by with gedit? Not when you must configure an application on your server in a data center two states away! When it comes to remote system administration, all roads lead back to Vim. Not a Vim expert? No problem, you just need a handful of commands to do everything you need to do.
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Now that we got a brief description of a hostname and basic configuration steps, its time to reflect another important case which is directly related to a Funtoo Linux hostname generation, a hosts.
  
Entire books have been written about Vim, and they still fail to capture all of its functionality. But the core command set is all you really need if you're just making a few changes to a few files over SSH. You might not do it as efficiently as a Vim expert, but it's good enough to get the job done. In fact, if you're working with Vim (the pre-eminent vi-clone) on a server, there's a good chance it's "vim-tiny," a stripped-down Vim that offers the traditional vi functionality but not the full set of Vim features.
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==Hosts case==
 
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As per man page <code>hosts</code> stands for static table lookup for hostnames and it's configuration file is <code>/etc/hosts</code>. Here is how it looks
==Insert Mode==
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{{file|name=/etc/hosts|body=
The first thing you must grok is that Vim has several modes -- command mode, insert mode, and last-line mode (also known as ex mode). When you start Vim, you'll be in command mode. Here, all of the keys are used to perform commands, not input text. To switch to input mode, hit <span style="color:green">i</span>, and you're able start editing the file, adding text, using Backspace, etc.
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# Auto-generated hostname. Please do not remove this comment.
To return to command mode, hit <span style="color:green">Esc</span>. To enter last-line or Ex mode, use :, and then input the command you wish to enter.
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127.0.0.1      oleg-stable.host.funtoo.org oleg-stable localhost localhost.localdomain
 
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::1             oleg-stable.host.funtoo.org oleg-stable localhost localhost.localdomain
==Vim Command Mode==
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I could go on for days about the commands needed in command mode, but we're just here for the basics, so let's look at movement. Movement is based on the standard alphabetic keys:
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* '''h''' Move the cursor to the left one character.
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* '''l''' Move the cursor to the right one character.
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* '''j''' Move the cursor down one line.
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* '''k''' Move the cursor up one line.
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You can move faster by using <span style="color:green">b</span> and <span style="color:green">w</span> to move backward and forward by one "word" at a time, respectively. Vim looks at "words" as a string of alphanumeric characters. So "eix" is a word, but "eix-sync" is multi-word because it's broken up by a non-alphanumeric character.
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Deleting is done with  <span style="color:green">d</span> or  <span style="color:green">x</span>. To delete a single character, move the cursor over that character and use <span style="color:green">x</span>. Using <span style="color:green">dw</span> will delete the word the cursor is over, and <span style="color:green">db</span> will delete the previous word.
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To delete an entire line, use <span style="color:green">dd</span>. To delete from the cursor to the end of the line, use <span style="color:green">d$</span>. To delete from the cursor to the beginning of the line, use <span style="color:green">d0</span>. The $ is shorthand for "end of the line," and 0 is shorthand for beginning of the line. You can also use ^ (shorthand for "first non-blank character of the line").
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==Copying and Pasting in Vim==
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Let's look at copying and pasting real quick. To highlight text to copy, use the <span style="color:green">v</span>, <span style="color:green">V</span> and <span style="color:green">Ctrl-V</span> commands. You might have guessed by now that Vim commands are case-sensitive, So v and V are different things.
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The <span style="color:green">v</span> command simply allows you to highlight changes character by character using the movement (hljk and others) or arrow keys. The <span style="color:green">v</span> command highlights entire lines. And the <span style="color:green">Ctrl-v</span> command highlights blocks of text -- very useful for highlighting and copying columns of text.
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Once you've highlighted the text you want to copy, hit <span style="color:green">y</span> to "yank" the text into the buffer.
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To paste the text, use <span style="color:green">p</span> or <span style="color:green">P</span> to paste. The p command will paste after the cursor, and P pastes before the cursor.
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==Search and Replace==
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To search through the document, use the / key to initiate a forward search, or ? to initiate a backward search.
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To search and replace, use <span style="color:green">:s</span> with the range of lines and search terms. Like so:
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<pre>
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:%s/old/new/
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</pre>
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The % means "global," but you can replace that with a range of lines, like this:
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<pre>
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:1,15s/old/new/
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</pre>
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Another example of search/replace functions
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<pre>Command        Outcome
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:s/xxx/yyy/    Replace xxx with yyy at the first occurence
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:s/xxx/yyy/g  Replace xxx with yyy first occurrence, global (whole sentence)
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:s/xxx/yyy/gc  Replace xxx with yyy global with confirm
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:%s/xxx/yyy/g  Replace xxx with yyy global in the whole file</pre>
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I prefer to use the <span style="color:green">c</span> (confirm) and <span style="color:green">g</span> (global) options too, so when searching it will search the entire line and not just the first occurrence of a string.
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A usual search would look something like :%s/old/new/gc, and when you hit Enter you'll be prompted before you make changes. I recommend using confirm; otherwise you can wind up with unexpected results.
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==Undo==
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What if you've made an edit you didn't want to make? Easy, use the undo <span style="color:green">u</span> command. If you didn't mean to undo what you did -- and it's easy to accidentally hit u -- use <span style="color:green">Ctrl-r</span> to redo the last change.
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Quick note: If Vim is in vi-compatibility mode, it will have only one "level" of undo. In normal Vim mode, you can undo many, many changes. But vi undoes only the most recent change.
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==Saving, Quitting and More ...==
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One of the things that's severely non-obvious while working with Vim the first time is how do I get the heck out of here? You can quit Vim in a number of ways, but I'll show the most usual ones.
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First, if you want to save your changes before exiting Vim, use  <span style="color:green">:w</span> or save and exit in one action with <span style="color:green">:wq</span>.
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Don't want to save your changes? It happens. No problem, just use <span style="color:green">:q!</span> if you realize that you've made some edits that you don't want to save, and they are too complex to easily undo before exiting. Note that you can also write changes to a different filename by using :w newfile.
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This is just a short and sweet intro to Vim for emergencies or minimal usage. You could do much, much more with Vim if you wanted. Be sure to read through the Vim tutorial by running vimtutor, and look through Vim's documentation by running :help. But in a pinch, this list of commands should get you through.
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== Good Starter Vimrc ==
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The following file makes a very good starter <tt>.vimrc</tt> file. Place it in your home directory, and you will get true tabs (displayed indented 4 spaces) and you will be able to see all the whitespace in your document, which is handy when editing critical files:
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{{file|name=~/.vimrc|desc=A good starter .vimrc file|body=
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set noexpandtab
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set shiftwidth=4
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set tabstop=4
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set listchars=eol:%,tab:>-,trail:~,extends:>,precedes:<
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set list
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filetype indent off
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filetype plugin off
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}}
 
}}
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As you can see it has entries from our <code>/etc/conf.d/hostname</code>. As you may have guessed, in Funtoo Linux <code>/etc/hosts</code> file entries are auto-generated, when OpenRC hostname service starts. Previously, it is used to edit <code>/etc/hosts</code> manually. In Funtoo Linux there is no such need.
  
By default, copying and pasting into a vim window will cause things to horribly auto-indent. To fix this, add the following to your <tt>.vimrc</tt> file:
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What about custom hosts entries? This can be easily configured with 'aliases'. For example you want to have a hosts for your remote router or a computer in home LAN. Let's try to modify <code>/etc/conf.d/hostname</code> with adding following - my remote computer oleg.distant.home has an IP 10.1.1.2:
 
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<console>
{{file|name=~/.vimrc|desc=fix pasting auto-indentation|body=
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oleg-stable ~ # ##i## echo 'aliases="10.1.12 oleg.distant.home"' >> /etc/conf.d/hostname
set noai
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oleg-stable ~ # ##i## service hostname restart
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</console>
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Examine our changes:
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<console>
 +
oleg-stable ~ # ##i## cat /etc/hosts
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</console>
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{{file|name=/etc/hosts|body=
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# Auto-generated hostname. Please do not remove this comment.
 +
10.1.1.2        oleg.distant.home
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127.0.0.1      oleg-stable.host.funtoo.org oleg-stable localhost localhost.localdomain
 +
::1            oleg-stable.host.funtoo.org oleg-stable localhost localhost.localdomain
 
}}
 
}}
 
Alternatively, you can temporarily switch to "paste mode" before pasting with <span style="color:green">:set paste</span>. You will see <tt>-- INSERT (paste) --</tt> in the status bar when you are in insert mode. Don't forget to disable paste mode with <span style="color:green">:set nopaste</span> after pasting. You can also use bang to switch between "paste" and "nopaste" so that you just have to recall the last command : <span style="color:green">:set paste!</span>. ([http://vim.wikia.com/wiki/Toggle_auto-indenting_for_code_paste See also])
 
 
{{EbuildFooter}}
 

Revision as of 16:06, February 24, 2015

Introduction

A hostname is a unique name created to identify a machine on a network. In computer networking, a hostname is a label that is assigned to a device connected to a computer network and that is used to identify the device in various forms of electronic communication such as the World Wide Web, e-mail or Usenet. Hostnames may be simple names consisting of a single word or phrase, or they may be structured.

Configuration

In Funtoo Linux /etc/conf.d/hostname is the only configuration file for setting a hostname. In OpenRC framework /etc/conf.d/foo is the configuration file for a corresponding Init script /etc/init.d/foo. With the case of hostname, default value in /etc/conf.d/hostname is set to localhost, means when system boots and OpenRC's /etc/init.d/hostname script started a hostname getting only localhost name. How it looks? In your shell promt this will look in following way, an example for root:

localhost ~ #  Hello :)

Let's play a bit with a configuration. Open /etc/conf.d/hostname with your favorite editor and set a hostname of your choice. Below, I will use a real examples from one of my working test boxes.

localhost ~ #  nano /etc/conf.d/hostname

Let's set it to hostname="oleg-stable.host.funtoo.org". Save the file and restart a hostname service:

localhost ~ #  service hostname restart

Now, let's examine our changes, after a restarting a hostname

oleg-stable ~ #  Hello :)

Diving deeper

Notice, that in above output we seeing a shortened hostname and not a FQDN (Fully Qualified Domain Name). Don't be frustrated. This is how default bash promt PS1 set. To get nice promts, please, follow http://www.funtoo.org/Prompt_Magic Another way to test our settings is using a hostname command. Here we will show only some of it's features. Let's try to execute hostname command:

oleg-stable ~ #  hostname
oleg-stable.host.funtoo.org

Now we see our fully qualified domain name hostname just how we configured it in /etc/conf.d/hostname in above paragraph. To get a short hostname we need to set -s (short) argument to hostname command.

oleg-stable ~ #  hostname -s
oleg-stable

Good! Hostname offers more then just displaying a system host name but can also set one. Let's try:

oleg-stable ~ #  hostname foo.bar.baz
oleg-stable ~ #  hostname 
foo.bar.baz

As you can see, we changed a hostname on-the-fly. This is not recommended way.

Warning

Please, notice that using hostname command to configure will work temporary for a current session and will be reverted back to a value set in /etc/conf.d/hostname file with next system restart.

Now that we got a brief description of a hostname and basic configuration steps, its time to reflect another important case which is directly related to a Funtoo Linux hostname generation, a hosts.

Hosts case

As per man page hosts stands for static table lookup for hostnames and it's configuration file is /etc/hosts. Here is how it looks

/etc/hosts
# Auto-generated hostname. Please do not remove this comment.
127.0.0.1       oleg-stable.host.funtoo.org oleg-stable localhost localhost.localdomain
::1             oleg-stable.host.funtoo.org oleg-stable localhost localhost.localdomain

As you can see it has entries from our /etc/conf.d/hostname. As you may have guessed, in Funtoo Linux /etc/hosts file entries are auto-generated, when OpenRC hostname service starts. Previously, it is used to edit /etc/hosts manually. In Funtoo Linux there is no such need.

What about custom hosts entries? This can be easily configured with 'aliases'. For example you want to have a hosts for your remote router or a computer in home LAN. Let's try to modify /etc/conf.d/hostname with adding following - my remote computer oleg.distant.home has an IP 10.1.1.2:

oleg-stable ~ #  echo 'aliases="10.1.12 oleg.distant.home"' >> /etc/conf.d/hostname
oleg-stable ~ #  service hostname restart
Examine our changes:
oleg-stable ~ #  cat /etc/hosts
/etc/hosts
# Auto-generated hostname. Please do not remove this comment.
10.1.1.2        oleg.distant.home
127.0.0.1       oleg-stable.host.funtoo.org oleg-stable localhost localhost.localdomain
::1             oleg-stable.host.funtoo.org oleg-stable localhost localhost.localdomain