.

## dimanche 10 juillet 2016

### damn you prolog, I mean damn you university

Everybody should learn prolog. It's such a wonderful piece of idea.

If you express a graph as:

transition(S, a, T)
transition(S, b, U)
transition(T, 0, V)
transition(U, 0, K)
transition(T, c, K)
transition(U, a, U)
...

mark a special node as an accepting state

accept(c, K)

then validating input is only:

validate(S, [I|IS]) :-
accept(I,S).
validate(S, [I|IS]) :-
transition(S,I,X),
validate(X,IS).

how daming is that.

## dimanche 22 mai 2016

### Programmation par l'exemple en Caml par Louis Gacôgne - 25 euros merveilleusements depenses

Pour ceux qui ont deja des bases en programmation, et en programmation fonctionnelle, ce petit manuel est une mine d'exercises aussi concis que generaux.

arbres, reines, graphes, hasard, lambda calcul, derivation symbolique, jamais trop de details, jamais pompeux ni trop succint... genial

http://www.decitre.fr/livres/programmation-par-l-exemple-en-caml-9782729819101.html

## mardi 3 mai 2016

### local ssh neighbors ?

A little bash function leveraging nmap .. mostly naive and fragile.
Until I learn how to do tcp|ip discovery.

```neigh_ssh ()
{
sudo nmap -v -p 22 --open --host-timeout 1 192.168.1.0/25 \
| grep --color=auto -E -o "open port 22.*[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}" \
| grep --color=auto -E -o "[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}" \
| sort \
| uniq
}
```

## dimanche 1 mai 2016

### systemd-nspawn and noexec flag

Trying to create customized archlinux iso (archiso, releng) I hit a lot of issues, most of them 'execv? failed, permission denied'.

Later on, just trying to run a systemd-nspawn container, again, execv permission. Boot fails.

Googling didn't get me very far, except to broaden the scope from systemd-nspawn to something more general. I try to run a binary (ls) from the container subtree. Permission denied. I md5sum container/.../ls and get the same md5 as the main linux install I'm running. I thought it could be the wrong architecture or a different binary. So if two binaries refuse to run .. maybe they're treated differently from the host OS. I then realize that my container and custom archiso were on a mounted drive.

mount | grep <mountpoint> -&gt; mount .... (...,noexec, ...)

EUREKA.

udevil mounts this drive with a lot of protective flags. udevil unmount <mountpoint>; sudo mount <device> /mnt; <container>/ ... /ls works.

systemd-nspawn -b -D <container> works.

Thanks to #archlinux for nothing (beside rubber ducking ;)</container></container></device></mountpoint></mountpoint>

## vendredi 22 avril 2016

### mtp under [arch]linux: mtpfs vs gvfs-mtp [mount update]

Wanted to copy some file from a Moto G to my laptop. Installed mtpfs. Mounting took minutes and failed. As a last hope I tried gvfs-mtp. I don't know how to use the gvfs-* CLI though. But it's supposed to work out of the box in GTK apps. So Chromium + Ctrl-O. I can see the smartphone listed. Walk through the phone FS. It's instantaneous, snappy as I like it. But what about the CLI ?

Well gvfs-info says nothing. There's gvfs-mount, which says nothing. gvfs-mount --list outputs the mounted drives on this machine. And the last one is mtp://[usb:005,009]/ ... Hmm maybe gvfs-ls takes an URI ?

\$ gvfs-ls mtp:/// # Error: The specified location is not mounted
\$ gvfs-ls mtp://  # Error: The specified location is not mounted
\$ gvfs-ls mtp:///sdcard # same as above

could the [usb:...] be mandatory ? odd syntax but alas

\$ gvfs-ls mtp://[usb:005,009]/
Internal Storage # yay

\$ gvfs-tree mtp://[usb:005,009]/ | head -n 32
mtp://[usb:005,009]/
`-- Internal Storage
|-- .CM_Cloud
|   |-- cm
|   |   |-- cm_cloud_sdk_expand.db
|   |   `-- cm_cloud_sdk_expand.db-journal
|   `-- cmqp
|       |-- cm_cloud_sdk_expand.db
|       `-- cm_cloud_sdk_expand.db-journal
|-- .DataStorage
|   `-- ContextData.xml
|-- .UTSystemConfig
|   `-- Global
|       `-- Alvin2.xml
|   |-- local_Thumb
|   |   |-- Fonts
|   |   `-- Sample Drawings
|   |       |-- Villa.dwg.png
|   |       |-- ar_house_2.dwg.png
|   |       |-- crane.dwg.png
|   |       `-- l_1a.dwg.png
|   |-- resources
|   |   |-- arialuni.ttf
|   |   |-- plotstyle
|   |   |   |-- Monochrome.ctb

Didn't try to copy anything yet, I guess it won't be worse than doing a full http roundtrip over wifi as I did before.

ps: there was a side effect of trying gvfs through GTK file open dialog. It mounted the volume on click. Thus the ability to use gvfs-* afterwards.

So there's a few things to do in cli beforehand.

source: http://stackoverflow.com/questions/483460/how-to-mount-from-command-line-like-the-nautilus-does

\$ gvfs-mount --list
Volume(0): XT1032
Type: GProxyVolume (GProxyVolumeMonitorMTP)

This shows XT1032 (Moto G) is detected but not mounted. What we want is the following:

\$ gvfs-mount --list
Volume(0): XT1032
Type: GProxyVolume (GProxyVolumeMonitorMTP)
Mount(0): XT1032 -&gt; mtp://[usb:005,013]/
Mount(1): mtp -&gt; mtp://[usb:005,013]/
Type: GDaemonMount

Usually to mount a 'storage' device, one uses /dev/sd*. But there's no sd* node for the XT1032.
gvfs-mount --list --info lists a bit more info (sic) (errata: --list -i)

\$ Volume(0): XT1032
Type: GProxyVolume (GProxyVolumeMonitorMTP)
ids:
unix-device: '/dev/bus/usb/005/013'
activation_root=mtp://[usb:005,013]/
themed icons:  [phone]
symbolic themed icons:  [phone-symbolic]  [phone]
can_mount=1
can_eject=0
should_automount=1

And trying with the /dev/bus/... path

\$ gvfs-mount -d /dev/bus/usb/005/013
Mounted /dev/bus/usb/005/013 at /run/user/1000/gvfs/mtp:host=%5Busb%3A005%2C013%5D

\$ gvfs-ls mtp://[usb:005,013]/
Internal Storage

# yay

## mercredi 20 avril 2016

### usb key replicate

* usb key duplicate

* partition table

manual cgdisk

* rsync partitions

rsync -auv --progress <source></source> <target>

* rsync caveat : hard links, sparse file

warning: some sparse files may have huge virtual size
rsync, will attempt to expand them fully
i.e: docker devicemapper (60MB on disk, virtually 100G)

warning: some programs have one fat binary with hard links
rsync, will attempt to copy them fully
i.e: git, which has 114 hard links with different names

* BIOS boot (ef02) partition

dd if=/dev/sdX1 of=/dev/sdY1 bs=1M # simply

* grub

sudo grub-install --target=i386-pc --debug --boot-directory=/<root-mountpoint>/boot/ /dev/sdY

warning: do not mess the device names and mountpoint names as it may modify your host system grub config

* grub UUID

grub menuentry refers to source key UUID