Qemu

Author: cirosantilli

README.md

@@ -13,18 +13,25 @@ Includes Linux concepts and utilities that work on Linux, not necessarily in the
     1. [man](man.md)
     1. [info](info.md)
 1.  Base standards
-    1. [POSIX](posix.md)
-    1. [Linux](linux.md)
-    1. [LSB](lsb.md)
-    1. [FHS](fhs.md)
-    1. [GNU](gnu.md)
-1.  Kernel related
-    1. [Kernel](kernel/)
+    1.  [POSIX](posix.md)
+    1.  [LSB](lsb.md)
+    1.  [FHS](fhs.md)
+    1.  [GNU](gnu.md)
+1.  [Linux](linux.md)
+    1.  Alternatives
+        1. [Hurd](hurd.md)
+        1. [BSD](bsd.md)
+    1.  [Distros](distros.md)
+        1. [Minimal distros](minimal-distros.md)
+1.  [Kernel](kernel/)
     1. [System Call](system-call/)
     1. [sysctl](sysctl.md)
+    1. [dmesg](demesg.md)
+    1. [installkernel](installkernel.md)
 1.  Initialization
     1. [Install OS](install-os.md): how to install a new OS
     1. [Boot](boot.md)
+    1. [GRUB](grub.md)
     1. [Init](init.md): System V, Upstart
 1.  System information
     1.  [lsb_release](lsb_release.md)
@@ -45,6 +52,7 @@ Includes Linux concepts and utilities that work on Linux, not necessarily in the
         1. [e2fsck](e2fsck.md)
         1. [e2fsprogs](e2progs.md)
         1. [mke2fs](mke2fs.md)
+    1.  [fallocate](fallocate.md)
     1.  [fdisk](fdisk.md)
     1.  [FUSE](FUSE.md)
     1.  [fuser](fuser.md)
@@ -58,7 +66,29 @@ Includes Linux concepts and utilities that work on Linux, not necessarily in the
         1.  [proc filesystem](proc-filesystem.md)
         1.  [dev filesystem](dev-filesystem.md)
             1. [mknod](mknod.md)
-        1. [ramfs](ramfs.md)
+        1.  [sysfs](sysfs.md)
+        1.  [ramfs](ramfs.md)
+    1.  Files, directories
+        1.  [cp](cp.sh)
+        1.  [dd](dd.md)
+        1.  [du](du.md)
+        1.  [fdupes](fdupes.md)
+        1.  [find](find.md)
+        1.  links
+            1. [ln](ln.md)
+            1. [readlink](readlink.md)
+            1. [realpath](realpath.md)
+        1.  [locate](locate.md)
+        1.  [ls](ls.md)
+        1.  [read](read.md)
+        1.  [stat](stat.md)
+        1.  [tree](tree.md)
+    1.  File managers
+        1. [Krusader](krusader.md)
+        1. [vifm](vifm.md)
+    1.  [CD DVD](cd-dvd.md)
+        [isoinfo](isoinfo.md)
+        [eject](eject.md)
 1. [Terminal](terminal.md): terminal emulators, ANSI escapes, control characters
     1. [Guake](guake.sh)
 1.  Stream and file manipulation
@@ -97,24 +127,6 @@ Includes Linux concepts and utilities that work on Linux, not necessarily in the
     1. [cmp](cmp.md)
     1. [diff](diff.md)
     1. [wdiff](diff.md)
-1.  Files, directories
-    1.  [cp](cp.sh)
-    1.  [dd](dd.md)
-    1.  [du](du.md)
-    1.  [fdupes](fdupes.md)
-    1.  [find](find.md)
-    1.  links
-        1. [ln](ln.md)
-        1. [readlink](readlink.md)
-        1. [realpath](realpath.md)
-    1.  [locate](locate.md)
-    1.  [ls](ls.md)
-    1.  [read](read.md)
-    1.  [stat](stat.md)
-    1.  [tree](tree.md)
-1.  File managers
-    1. [Krusader](krusader.md)
-    1. [vifm](vifm.md)
 1.  Programming
     1. [ack](ack.sh)
     1. [ctags](ctags/)
@@ -168,7 +180,7 @@ Includes Linux concepts and utilities that work on Linux, not necessarily in the
     1. [tar](tar.md)
     1. [zip](zip.md)
     1. [ar](ar.md)
-1.  User operations
+1.  User accounts
     1. [id](id.md)
     1. [usermod](usermod.md)
 1.  [Desktop](desktop/): X, XDG, GNOME, KDE and related utilities
@@ -192,10 +204,9 @@ Includes Linux concepts and utilities that work on Linux, not necessarily in the
     1. [Kramdown](kramdown/)
     1. [Pandoc](pandoc/)
     1. [RST](rst/)
-1.  [Virtual machine](virtual-machine/)
+1.  [Virtualization](virtualization.md)
     1. [Docker](docker/)
     1. [QEMU](qemu.md)
-    1. [User mode Linux](user-mode-linux.md)
     1. [Vagrant](vagrang/)
 1.  [Configuration automation](config-automation.md)
     1. [chef](chef/)
@@ -222,9 +233,9 @@ Includes Linux concepts and utilities that work on Linux, not necessarily in the
 1.  Packages
     1. [util-linux](util-linux.md)
 1.  Misc
+    1. [BusyBox](busybox.md)
     1. [cron](cron.sh)
     1. [logrotate](logrotate.md)
-    1. [BusyBox](busybox.md)
     1. [xargs](xargs.md)
 1.  [Bibliography](bibliography.md)
 
@@ -234,7 +245,7 @@ Includes Linux concepts and utilities that work on Linux, not necessarily in the
     1. [devpts](devpts.md)
     1. [eCryptfs](ecryptfs.md)
     1. [rootfs](rootfs.md)
-    1. [sysfs](sysfs.md)
+    1. [MAKEDEV](makedev.md)
 1.  [Hardware](hardware.md)
     1.  [lshw](lshw.md)
 1.  [gcov](gcov.md)

bibliography.md

@@ -10,6 +10,10 @@
 
     - <http://www.tldp.org/>
 
+-   `git clone http://git.kernel.org/pub/scm/docs/man-pages/man-pages`
+
+    Contains lots of Linux man pages. TODO compare to glibc.
+
 -   <http://linux.die.net/>
 
     Linux man pages: both form the Linux Documentation Project, and
@@ -25,3 +29,15 @@
 -   Linux from scratch
 
     Teaches how to build a minimal Linux distro
+
+-   <https://wiki.archlinux.org/>
+
+    Arch Linux wiki.
+
+    Amazingly good wiki, probably because Arch users are both hardcore and minimalistic.
+
+## Funny
+
+-   <http://www.cavecanen.org/linux/humour/horrorstories.txt>
+
+    Real *NIX sysadmin horror stories of things gone terribly wrong.

blkid.md

@@ -19,3 +19,13 @@ Sample output:
 	/dev/sdb7: UUID="3fabbe75-0c62-4705-a3ad-4e87c5dcc143" TYPE="ext4"
 	/dev/sdb8: UUID="56886cc6-e247-488a-9acf-a07a99cfa3ca" TYPE="ext4"
 	/dev/sdb9: UUID="bbc2c9bf-4846-44d1-81c0-eade6d2dcefb" TYPE="swap"
+
+Can also be used to identify files that contain filesystems, e.g.:
+
+    blkid ubuntu-14.04.2-desktop-amd64.iso
+
+outputs:
+
+    ubuntu-14.04.2-desktop-amd64.iso: LABEL="Ubuntu 14.04.2 LTS amd64" TYPE="iso9660" 
+
+If it cannot be identified, it prints nothing and returns `4`.

boot.md

@@ -39,145 +39,21 @@ The MBR points to a second stage bootloader in its disk which which will do the
 
 The most popular second stage bootloader for Linux now is GRUB. LILO was a popular alternative in the past. Windows has its own bootloader.
 
-## GRUB
-
-Grand Unified Bootloader.
-
-If you have a Linux dual boot, and you see a menu prompting you to choose the OS, there is a good chance that this is GRUB, since it is the most popular bootloader today.
-
-It allows you basic graphical interaction even before starting any OS.
-
-Everything is configurable, from the menu entries to the background image. This is why Ubuntu's GRUB is purple.
-
-The main job for GRUB userspace utilities such as `grub-install` and `update-grub` is to look at the input configuration files, interpret them and write the output configuration information to the correct locations on the hard disk so that they can be found at boot time.
-
-GRUB has knowledge about filesystems, and is able to read configuration files and the disk image from it.
-
-### GRUB versions
-
-GRUB has 2 versions
-
--   0.97, usually known just as GRUB, or Legacy GRUB.
-
--   GRUB >= 2, which is backwards incompatible, and has more features.
-
-    GRUB 2 is still beta.
-
-Some distros like Ubuntu have already adopted GRUB 2, while others are still using GRUB for stability concerns.
-
-Determine your GRUB version with:
-
-    grub-install -v
-
-Here we discuss GRUB 2.
-
-### configuration
-
-Input files:
-
--  `/etc/grub.d`
-- `/etc/default/grub`
-
-Generated files and data after `sudo update-grub`:
-
-- `/boot/grub/grub.cfg`
-- MBR bootstrap code
-
-#### /etc/default/grub
-
-    sudo vim /etc/default/grub
-
--   `GRUB_DEFAULT`: default OS choice if cursor is not moved.
-
-    Starts from 0, the order is the same as shown at grub os choice menu.
-
--   `GRUB_TIMEOUT` : time before auto OS choice in seconds
-
--   `GRUB_CMDLINE_LINUX_DEFAULT`: space separated list of Kernel boot parameters.
-
-    Documented at:
-
-        man bootparam
-
-    Those parameters can also be edited from the boot menu for single session by selecting the partition and clicking `e`.
-
-	Most important to know:
-
-	-   useless options on by default on Ubuntu 12.04 which you should really remove because they hide kernel state and potentially useful debug information:
-
-        - `quiet`: suppress kernel messages.
-        - `splash`: shows nice and useless image while the kernel is booting. On by default on Ubuntu 12.04. Remove this useless option,
-
-#### /etc/grub.d/
-
-Contains executables.
-
-Each one is called in alphabetical order, and its stdout is used by GRUB.
-
-Create a menu entry:
-
-    #!/bin/sh -e
-    echo "stdout"
-    echo "stderr" >&2
-    cat << EOF
-    menuentry "menuentry title" {
-    set root=(hd0,1)
-    -- boot parameters --
-    }
-    EOF
-
-You will see `stdout` when running `update-grub`. stderr is ignored.
-
-`set root=(hd0,1)` specifies the partition, here `sda1`. `hd0` means first device,
-`1` means first partition. Yes, one if 0 based, and the other is 1 based.
-
-`-- boot parameters --` depends on your OS.
-
-Linux example:
-
-    linux /boot/vmlinuz
-    initrd /boot/initrd.img
-
-Windows example:
-
-    chainloader (hdX,Y)+1
-
-It is common to add one OS menu entry per file so that it is easy to change their order (just change alphabetical order).
-
-#### os_prober
-
-Looks for several OS and adds them automatically to GRUB menu.
-
-Recognizes Linux and Windows.
-
-TODO how to use it
-
-#### update-grub
-
-Interpret input configuration files and update `/etc/default/grub` which will be used at boot time.
-
-You must to this every time you change the input configuration files for the changes to take effect.
-
-#### grub-install
-
-Interpret input configuration files and update the MBR on the given disk:
-
-    sudo grub-install /dev/sda
+## boot directory
 
-If for example you install a new Linux distro, and you want to restore your old distro's GRUB configuration, you must log into the old distro and do `grub-install`, therefore telling your system via the MBR to use the installation parameters given on the old distro.
+Usually located at `/boot/`.
 
-### Sources
+It contains the following files:
 
--   <http://www.dedoimedo.com/computers/grub-2.html>
+- `config-VERSION`: the kernel configuration options, generated at configuration before kernel compilation by `make menuconfig`
+- `abi-VERSION`: TODO what is? Looks like the kernel symbol table of exported symbols.
 
-    Great configuration tutorial.
+### vmlinuz
 
-## boot directory
+Compiled kernel compressed with gzip, thus the `Z`
 
-Usually located at `/boot/`.
+#### vmlinux
 
-It contains the following files:
+#### bzimage
 
-- `vmlinz-VERSION`: the kernel compiled code, also knows as kernel image.
-- `config-VERSION`: the kernel configuration options, generated at configuration before kernel compilation by `make menuconfig`
-- `abi-VERSION`: TODO what is? looks like the kernel symbol table of exported symbols.
+<http://unix.stackexchange.com/questions/5518/what-is-the-difference-between-the-following-kernel-makefile-terms-vmlinux-vml>

bsd.md

@@ -0,0 +1,20 @@
+# BSD
+
+<https://en.wikipedia.org/wiki/Berkeley_Software_Distribution>
+
+Derived from AT&T.
+
+OS X is a fork.
+
+Major differences from Linux:
+
+- license: BSD license, which allowed Apple to fork
+- scope: the project also includes userspace utilities. Interesting as it ensures that they work together with the kernel.
+
+Why it lost from Linux: <http://serverfault.com/questions/36359/why-is-linux-more-popular-than-bsd> An important factor was the AT&T legal case against BSD at the kernel explosion of the early 90's, which held it back at the critical moment. GPL also likely helped Linux by forcing enterprises to contribute and not only leech.
+
+Main variants:
+
+- FreeBSD
+- OpenBSD
+- NetBSD

busybox.md

@@ -2,19 +2,18 @@
 
 Single executable that includes all POSIX command line utilities, including `sh`, and no libc dependency.
 
+The logo "The Swiss Army Knife of Embedded Linux" does it great justice: it is small and has many utilities, just like a swiss knife.
+
 Popular for minimal distributions, e.g. <https://github.com/ivandavidov/minimal>
 
-Source:
+Quickstart:
 
     git clone git://git.busybox.net/busybox
+    make defconfig
+    make
+    make install
 
-Once compiled, this generates a single `busybox` 2Mb executable, possibly with not external dependencies, often built with uClibc. E.g., if we do:
-
-    ldd busybox
-
-we get:
-
-
+This generates a single `busybox` 2Mb executable. It is common to configure it to embed libc so it will work in systems without it. TODO how
 
 It is also possible to configure exactly which utilities will be present on the output.
 
@@ -28,3 +27,13 @@ or with symlinks, which is the standard approach when deploying it:
     ./echo a
 
 `busybox` uses `argv[0]` to decide the executable in this case.
+
+`make` install generates an `_install` directory with all utilities symlinked to `busybox`.
+
+## init
+
+BusyBox also implements a version `init`, which is capable of reading `/etc/inittab` to startup the system.
+
+Even though Ubuntu 14.04 does not have it installed by default, its boot system adds it to the `/boot/initrd*` files. Poetically speaking, the initial boot environment has characteristics of an embedded system.
+
+It is then the job of `init` to mount