MestreLion's questions

Nautilus was not generating thumbnails for some xpm files I had, so I tried to investigate who was responsible for generating thumbnails for xpm files (if any), or any image for that matter. And I stumbled into a wall of misinformation, obsolete specs and frustrated searches.

So, where is the thumbnailer for such "basic" images defined? I've checked /usr/share/thumbnailers and it only mentions pdf, exe, and video files. No mention of png, jpg bmp, etc. Where are thumbnails of images defined? Wat are the official references about it?

My network is somewhat simple: all PCs in my LAN (Ubuntu desktop, Win7 desktop, XP netbook) connected to a dlink home router, which is connected to ISP's cable modem. LAN has IP subnet 10.10.10.0/24, gateway (the dlink router) is 10.10.10.1, the PCs are 10.10.10.100-120, via DHCP. The PCs share folders among themselves (basic right-click -> share, this is samba, right?). So far, so good.

Now the Ubuntu desktop has VirtualBox. I was planning on installing sandboxed VMs to test malware (and monitor the way they "call home"). So I installed an Ubuntu VM, network set to NAT mode (the default mode, subnet 10.0.2.0/24 I guess).

So I open up Nautilus in the VM, go to "network", and to my surprise... the VM is able to see all the shared folder in the host's LAN!!!

How? Isn't "Shared Folders" something that works on the LAN only? How come a VM that lives in another subnet can access, say, a shared folder in the Win7 machine? They are not in the same LAN! (that would be Virtualbox's "Bridged" mode, correct?). And no, I do not mean VirtualBox's "Share Folder" feature (that maps a host drive as a network share to the guest), I'm not using it.

So, I clearly lack some fundamental knowledge of how shared folders and NAT works.I assumed NAT would isolate the VM from my LAN while still being able to browse the internet. I am very surprised it was able to see my LAN's workgroups even being in a different subnet.

So, question is: How is that possible? How this relation between VirtualBox, Shared Folders and NAT works? And how to setup the VM so it can't see the guest's LAN but is still able to browse the internet?

Is there any open source Java Decompilers for Ubuntu, preferably in the repositories and/or GPL'ed?

Both JAD and JD, the most popular decompilers I've found after a bit of googling, seems to be available only in binary form. And they are both proprietary.

It's hard to believe there is no such software in Ubuntu (or Linux in general).

If there is more than one, which you recommend, and why?

I connect my PC to my home theater via SPDIF, so when watching video files that uses AAC 5.1 channels, it is downmixed to stereo and the surround channels are lost.

I would like to be able to convert all 5.1 AAC output to 5.1 AC3, so my HT properly plays 6 discrete chanels.

My current approach is to use avconv to convert my files's audio streams like this:

avconv -i <inputfile> -codec copy -codec:a ac3_fixed -b:a 448k <outputfile>

It works, but it has a few drawbacks:

• All audio streams are converted to AC3, even the ones I don't need or want to, like stereo, DTS or AC3. I would like to convert only the AAC 5.1 ones. Command should be generic enough so I don't have to inspect the file or pick streams manually.

• While conversion works fine, there are a few issues: volume is huge, loud as I've never seen before, and I fear some metadata is lost on conversion.

• I must run this for every video I want to watch. It takes time and waste a lot of HDD space.

So, is there a solution that fixes at least one of these drawbacks?

Possible approaches:

• Set OS (pulse audio?) to encode multichannel PCM to AC3 on-the-fly? (that would be amazing, since it would not only with videos but also for games.

• Fix my command line with some smart parameters

Thanks!

http://packages.ubuntu.com is an amazing website for finding information about packages. I can see how a given package evolved in each release, can compare differences (from Maverick to Precise, for example), download other releases's versions to study or even backport them, etc. It has links to the Debian equivalent, launchpad, etc. It's an amazing cross-release package control panel. I even added its search to my firefox custom searches.

So, the question is:

Is there any similar website for the partners repository?

... and what about security? And extras?

My google skills may be rusty, but I couldn't find it.

Thanks!

I have the current scenario:

• 16GB or RAM. For the most part, around 10~12GB unused

• Almost never install/remove software, this is a mature system

• Only reboot like once a week, so (re-)boot time is irrelevant

• /usr is around 8GB

• HDD is slow, and no budget to change that in the near future

• Mounting /tmp as tmpfs in fstab did wonders for performance

And I just had this crazy idea:

Is it possible to, somehow, use my RAM to "store" /usr?

In that that, when starting up, it reads current /usr content from HDD and copy it to a tmpfs and mount that as /usr?

If possible, also flushing the (perhaps updated) contents back to HDD when shutting down? Or maybe allowing me to easily "temporarily switch back to HDD" when eventually needed to install/remove new software or updates?

Any approach is welcome, ready-to-use commands will be highly regarded.

Thanks!

This is easily done for a single file type, as answered in How to associate a file type within Wine with a native application?, by creating a .reg for the desired filetype. But this is for AVI only. I use some wine apps (uTorrent, Soulseek, Eudora, to name a few) that can launch a wide range of files. Email attachments, for example, can be JPG, DOC, PDF, PPS... its impossible (and not desirable) to track down all possible file types that one may receive in an email or download in a torrent.

So I neeed a solution to be more generic and broad. I need the file association to honor whatever native app is currently configured. And I want this to be done for all file types configured in my system.

I've already figured out how to make the solution generic. Simply replacing the launched app in .reg for winebrowser, like this:

[HKEY_CLASSES_ROOT\.pdf]
@="PDFfile"
"Content Type"="application/pdf"
[HKEY_CLASSES_ROOT\PDFfile\Shell\Open\command]
@="C:\\windows\\system32\\winebrowser.exe \"%1\""

Ive tested this and it works correctly. Since winebrowser uses xdg-open as a backend, and converts my windows path to a Unix one, the correct (Linux) app is launched.

So I need a "batch" updater to wine's registry, sort of a wine-update-associations script that I can run whenever a new app is installed. Maybe a tool that can:

• List all Mime Types types in my system that have a default, installed app associated
• Extract all the needed info (glob, mime type, etc)
• Generate the .REG file in the above format

The tricky part is: i've searched a LOT to find info about how association is done in Ubuntu 10.10 onwards, and documentation is scarce and confusing, to say the least. Freedesktop.org has no complete spec, and even Gnome docs are obsolete. So far I've gathered 4 files that contain association info, but im clueless on which (or why) to use, or how to use them to generate the .reg file:

~/.local/share/applications/mimeapps.list
~/.local/share/applications/miminfo.cache
/usr/share/applications/miminfo.cache
/etc/gnome/defaults.list

Any help, script or explanation would be greatly appreciated!

Thanks!

I have some raw partition images created using dd this way:

dd if=/dev/sdXY of=/path/file.img

I know I can mount them using:

sudo mkdir /media/mountpoint
sudo mount -o loop /path/file.img /media/mountpoint

But... is there any easier way? I would like to have the same functionaly and ease-of-use as Nautilus handles .ISO CD/DVD images, which is:

• Double click to mount
• It shows up in Desktop and in Nautilus left panel
• Auto-detects filesystem (as mount does)
• No need of sudo or administrator privileges
• No need to pre-create a mountpoint folder (or to delete it afterwards)
• Handy "Eject" button to unmount

Ive tried renaming the images as .IMG, .BIN, .ISO, with no sucess. Also tried configuring Opwn With > Archive Mounter, and it didnt work.

How can I do that?

I will soon move my /home folder to a separate partition. There are hundreds of tutorials on how to do so, including here. While most agree on the basic steps, their details are very different. For copying files, for instance, some use rsync, some cp, and some find | cpio (Ill use rsync)

As for fstab entry, the options are puzzling me. The most common suggestions are:

UUID=xxx /home ext3 nodev,nosuid 0 2
UUID=xxx /home ext3 defaults,error=remount-ro 0 1
UUID=xxx /home ext4 error=remount-ro 0 1
UUID=xxx /home ext3 defaults 1 2

Its hard to know if those suggestions are outdated or obsolete. So, for Ubuntu 10.04 onwards, what are the best / recommended parameters for an ext4 /home? nodev,nosuid? defaults? Nothing? And, most important, why?

EDIT:

So far, im inclined to use

UUID=xxx /home ext4 nodev,nosuid 1 2

But I would like some background on that

While creating a 250GiB backup partition for my data, I have noticed lots of discrepancies between reported partition size and free space in Nautilus, gParted, df, tune2fs, etc.

At first I thought it was a GiB / GB confusion. It was not.

Then I thought it could be ext4's reserved blocks. It was not.

Im completely puzzled. Here are some images. Here are the steps:

• First, NTFS. 524288000 sectors x 512 bytes/sector = 268435456000 bytes = 268.4 GB = 250 GiB.

Nautilus say "Total Capacity: 250.0 GB" (even though its actually GiB, not GB). Apart from that minor mislabeling, so far, so good

• Now, same partition, formated as ext4 with gparted:

First, Last and Total sectors are the same. It IS the same 250GiB partition. Used size is 4.11GiB (reserved blocks maybe?)

Nope. Looks like reserved blocks are 12.7 GiB (~5%. ouch!). But... why Total Capacity is now only 246.1 GiB ???. That difference (sort of) matches the 4.11 GiB reported by gparted. But... if its not from reserved blocks, what is it? And why gparted didnt report that 12.7GiB of used space?

$ df -h /dev/sda5
Filesystem            Size  Used Avail Use% Mounted on
/dev/sda5             247G  188M  234G   1% /media/BACKUP

df matches Nautilus in reported free space. But.. only 188M used? Shouldnt it be ~12GB? And total capacity is still wrong. So i ran tune2fs to find some clues. (irrelevant output is ommited)

$ sudo tune2fs -l /dev/sda5
tune2fs 1.41.12 (17-May-2010)
Filesystem volume name:   BACKUP
Filesystem UUID:          613d592e-47f5-4206-96a7-210090d340ef
Filesystem features:      has_journal ext_attr resize_inode dir_index filetype extent flex_bg sparse_super large_file huge_file uninit_bg dir_nlink extra_isize
Filesystem flags:         signed_directory_hash 
Filesystem state:         clean
Filesystem OS type:       Linux
Block count:              65536000
Reserved block count:     3276800
Free blocks:              64459851
First block:              0
Block size:               4096

65536000 total blocks * 4096 bytes/block = 268435456000 bytes = 268.4 GB = 250 GiB. It matches gparted.

3276800 reserved blocks = 13421772800 bytes = 13.4 GB = 12.5 GiB. It (again, sort of) matches Nautilus.

64459851 free blocks = 264027549696 bytes = 264.0 GB = 245.9 GiB. Why? Shouldnt it be either 250-12.5 = 237.5 (or 250-(12.5+4.11)=~233) ?

Removing reserved blocks:

$ sudo tune2fs -m 0 /dev/sda5
tune2fs 1.41.12 (17-May-2010)
Setting reserved blocks percentage to 0% (0 blocks)

$ sudo tune2fs -l /dev/sda5
tune2fs 1.41.12 (17-May-2010)
Filesystem volume name:   BACKUP
Filesystem UUID:          613d592e-47f5-4206-96a7-210090d340ef
Filesystem features:      has_journal ext_attr resize_inode dir_index filetype extent flex_bg sparse_super large_file huge_file uninit_bg dir_nlink extra_isize
Filesystem flags:         signed_directory_hash 
Filesystem state:         clean
Filesystem OS type:       Linux
Block count:              65536000
Reserved block count:     0
Free blocks:              64459851
Block size:               4096

As expected, same block count, 0 reserved blocks, but... same free blocks? Didnt I just freed 12.5 GiB ?

$ df -h /dev/sda5
Filesystem            Size  Used Avail Use% Mounted on
/dev/sda5             247G  188M  246G   1% /media/BACKUP

Looks like I did. Avaliable space went up from 233 to 245.9 GiB. gparted didnt care at all, showing exactly same info! (useless to post an identical screenshot)

What a huge mess!

I tried to document it as best as I could... So, please can someone give me any clue on what's going on here?

• What are those misterious 4.11 GiB missing from NTFS -> ext4 formatting?
• Why there are so many discrepancies between gparted, Nautilus, tune2fs, df?
• What is wrong with my math? (questions in bold scattered this post)

Any help is appreciated. While I can not figure what is going on, I am serilously considering giving up on ext4 in favor of NTFS for everything but my / partition.

Thanks!

This has been asked several times already (I found it here, here and here), but basically everyone simply recommend to perform a full install to the USB stick. But I do need it to stay as a LIVE session, not a "full install on USB", for a number of reasons (the most important one being that using Live session I can easily install Ubuntu using the desktop icon)

So, my constraints for skipping the Welcome Screen (and automatically choose "Try Ubuntu" option) are:

• It must actually be the Ubuntu Live session (or as close to the default as possible). Same software selection (gparted is present in live sessions, gimp is not, for example), user (name and ID), behavior (no login screen, no password for sudo, to name a few), no GRUB, etc. That rules out an Ubuntu full install on USB.

• It must be able to install Ubuntu in the computer (while full install requires the ISO file, an additional USB stick, and the hassle of Startup Disk Creator)

• If possible, to be as fast as the "text-based launcher" (the one you have when you press a key right after the kernel loads)

• It must be completely automatic, unattended from boot to desktop.

• Select a different language than default. It can be a hard-corded selection (actually, it must, since boot itself shall be fully unattended). But preferably be easily changed ("easily" as in editing a config file then rebooting)

Is it possible?

The proposed (great) solutions that I've ruled out so far are:

• Installing Ubuntu in the USB stick (for all of the above mentioned reasons)

• Remove Ubiquity package (it removes the ability to install the system from that USB as well)

• Ubuntu Customization Kit (ubk): several limitations and caveats, and its not even in the repos

• Remastersys / LiLi: its the same as full direct USB install, only customized.

An ideal solution would be something like "create USB sick using Startup Disk Creator, then open it and remove / edit / add file(s) xxx, yyy, zzz"

Ive noticed a really annoying behaviour in Ubuntu: whenever I restart or shutdown the PC from a Live session, the USB stick becomes unavaliable when it reboots/turns on (as if the "safe removal" feature from windows was used)

Ive noticed this in 10.04, 10.10, 11.04, and even Linux Mint 10 and 11. Also happens with all USB sticks Ive tried (like 4 different models), in all machines (tested in like 5). So I think this is rather a feature than a bug/hardware issue.

But its really annoying. After playing in a Live Session, i must physically unplug-and-replug the USB stick so it works again.

Is there any way to disable this behaviour? So I can reboot my PC and use the Live Session again without unplugging and replugging the USB stick?

How does the "User Privileges" tab in the Advanced Settings of Users and Groups GUI work? I mean this window:

Does it simply add or remove the user from certain groups, or is there something else? If so, why only a few groups are represented there? I mean, how does Ubuntu/Gnome/Whatever decide which groups appear in that list? And where does the "description" for each "privilege" comes from?

As a side-note, Ive always been amazed of how incredibly terrible this GUI is: documentation is laughable, to say the least (click Help and see: only 3 pages, very outdated screenshots, obsolete and incomplete instructions, and not a single word on the Advanced Settings at all), also the design is completely counter-intuitive: theres no list at all of the groups a user belongs to. One must click "Manage Groups" and click properties for each and every group to see its users. Come on! How come such a major and ancient thing like Users and Groups Management still have no decent GUI?

The user created by Ubuntu on install is different than the ones you create using the "Users and Groups" tool - the user is "Custom" not "Administrator".

Besides being able to "sudo", what are the other differences?

Is it just groups and privileges, or is there something else?

Does install do anything else, like creating folders, files, config, that can not or are not done using the "Users and Groups" tool?

Somewhat related question: Users and Groups Administration tool - What do the options in User Privileges tab of Advanced Settings do?

Yes, this has been asked numerous times here, and Ive carefully read all the related questions. But very few focus on some of the issues that concerns me the most. So, given we now have a new Ubuntu 11.04 and new Linux Mint 11 recently released, its time for some upgrades! :D

I have Mint 10 installed, and would like to upgrade it to 11, and also install Ubuntu 11.01 Natty side-by-side in a separate partition.

Here is my current setup:

• 10 GB NTFS Win XP (gaming performance)
• 30 GB NTFS Win 7 (rarely used, im considering changing to Virtual Box instead)
• 30 GB EXT4 / Linux Mint 10 (my main OS)
• 5 GB swap (i have 4GB RAM)

And on sdb:

• a bazilion GB NTFS /dados (docs, music, videos, pics, ISOs, and all OS-neutral data)

That means /home currently holds basically only config files in the ~/.hidden folders.

My questions are:

• If my data is already in a separate partition, would a separate /home partition be any useful? Why and how?

• How would different (but similar) distros (Mint 10, 11, and Ubuntu Natty) behave when sharing the same /home partition? What about config files? Would, for instance, FireFox 3.6 (from Mint 10/Ubuntu Maverick) play nice with FireFox 4 if they both use the same ~/.firefox config folder? What about "system" setings like ~/.gconf, ~/.gnome2, ~/.config, etc? Wouldnt it be a nasty mess if a separate, shared /home is used? How that should be dealed with?

• Same goes for /boot: If each OS mounts it, wont they also change/upgrade them? Since each uses a different grub version, wont that mess it up? Any chances of version mismatch between the bootsector image and the /boot contents due to different Oses mounting / updating it?

• What about username / user ID / stored passwords? Would all distros behave correctly? I know the first user created in Ubuntu have some unique tweaks (ID=1000, tweaked permisions, etc). How would it be if Ubuntu is presented with a separate (and already existing) /home with a user at install? Would vault, for instance, works?

Im the only user of my computer, so multi-user flexibilty is not an great issue (but it would be nice if possible)

Given that, I would like some opinions, warnings, or any input that might help me to set up a good partition scheme. This is not an objective question, im looking for subjective suggestions and things to consider. Moderators feel free to change to community. Words on how ~/.config files work for different software versions in a shared and/or upgraded enviroment are greatly apreciated.

Thanks!

I have an Asus netbook, and its recovery partition and recovery DVD have several images in .WIM format.

Are there any Linux/Ubuntu tools to handle those images? Im looking for the equivalents of dism, ImageX, etc. But any tool (GUI or CLI) that could mount or extract or view its contents would be nice.

I have an Asus EeePC 1005PE netbook and I'm planning on doing a massive re-partitioning (going to install Ubuntu, Mint, XP, etc).

I've noticed it has 2 "special" partitions:

• a 10Gb Fat32 RESTORE hidden partition (used by BIOS "F9 recovery" feature)
• a 16Mb "unknown" partition at the end of the drive (used by BIOS "Boot Booster" feature)

So, for both partitions, my question is:

• Can I move/resize the recovery partition freely?

• What are the requirements for it? (I mean, for it still to be found by BIOS when I press F9/Activate BootBooster.) Partition table order? Partition type? Flags? Label? UUID?

• Can I make it a logical (instead of primary) partition?

• Must it be the flagged as boot?

Most importantly: Where can I find any official documentation about it? I've already seen much (mis)information about it. Some say Boot Booster partition must be last (in partition table), some say Recovery must be 2nd, that it must be bootable, etc. How can I know what is really needed for the BIOS to use both F9 and Boot Booster?

Note: I'm using GParted from a Live USB Stick (Mint 10 / Ubuntu 10.10), and I've noticed that, since the filesystem type of the Boot Booster is not recognized, it can't move or resize it. Can I delete it and re-create it somewhere else? Whenever I create a 0xEF partition GParted crashes and quits and I cannot open it again (must delete the partition using fdisk / cfdisk).

I have a netbook with Ubuntu Netbook 10.04 and a desktop with Mint 10 (~ Ubuntu Desktop 10.10)

Both of them have read/write NTFS partitions mounted via /etc/fstab. And it works fine.

Ive read on net, google, forums, and several posts here, that NTFS-3G is the driver that allows you to have full access to an NTFS partition, that it is new, great, powerful, yada-yada.

But... my entries use plain ntfs, no mention of -3g, and they still work perfectly as read and write. Am I already using ntfs-3g? Does 10.04 onwards use it "under the hood"? How can i check that in my system?

Should my /etc/fstab entries should use "ntfs-3g" as the fs? Why some posts refer to mount ntfs, while others say mount ntfs-3g ?

Im really confused about where should I use fs-type names (ntfs) or driver names (ntfs-3g?).

Or is it irrelevant now, and ntfs is always an "alias" or something for ntfs-3g nowadays?

Ive read some posts her, from Oct-10 and Nov-10 e that "announce" that ntfs-3g "finally arrived"... thats way post-Lucid 10.04.

Could someone please undo this mess in my head, and explain the relation between ntfs and ntfs-3g, what is the current status (10.04 and 10.10), where should i use each, etc (regarding mount, fstab, etc)?

Sorry for the long, confusing, redudant text... im really getting sleepy

When trying to manage trash can from mounted NTFS volumes, I ended up reading FreeDesktop.org's reference on it.

Poking around and doing some tests, I realized Ubuntu/Gnome does not follow the specs 100%. Here's why:

• For non-/ partitions, it always uses <driveroot>/.Trash-<uid>, It never used <driveroot>/.Trash/<uid>, even when i created it in advance. While this works, it's annoying: if I have 15 users, I end up with 15 /.Trash-xxx folders in my drive, while the other approach would still give a single folder (with 15 sub-folders). That "pollution" in my drives is very unpleasant. And specs say "If an $topdir/.Trash directory is absent, an $topdir/.Trash-$uid directory is to be used". Well, it is present, so why does it never use it?

• root trash does not work, at least not out of the box. Open nautilus as root and click on trash; it gives an error. Try to delete any file, it says "it can't move to trash". Ok, I know this can be fixed by creating /root/.local/share. But specs says "A “home trash” directory SHOULD be automatically created for any new user. If this directory is needed for a trashing operation but does not exist, the implementation SHOULD automatically create it, without any warnings or delays.". Why the error then? Bug?

• Why must I change /etc/fstab entries for mounted volumes, adding options like uid and guid, if the volumes are already mounted as RW for everyone?

These are just some examples of deviation from the standard. So, the question is:

"If Ubuntu does not adhere 100% to the spec, HOW exactly does the trash work? WHERE can i find a technical reference for Ubuntu's implementation of the trash?"

By the way: if Ubuntu does happen to follow specs, please tell me what I am doing wrong, especially regarding the /.Trash-<uid> vs /.Trash/<uid> issue.

Thanks!

EDIT:

Some more info:

• If a given fs has no support for the sticky bit (VFAT, NTFS), it probably doesn't have for permissions either (at least VFAT surely doesn't). So what prevents one user from purging / restoring other users' ./Trash-xxx ? If one can read/write his own Trash, one can do the same for the whole drive, including other's trashes, correct? Or does Gnome have some kind of "extra" protection on ./Trash-xxx folders on VFAT/NTFS fs?

• If Linux can "emulate" file permissions on NTFS mounting by editing /fstab uid and gid options, can it also "emulate" the sticky bit? I would really prefer to use /.Trash/xxx format...

• For the root issue: for the / partition, I can use trash as root, and it goes to /root/.local/share/Trash. But if I click on Nautilus "Trash" (as root), I get an error. Don't you? So files are correctly trashed, but I can't access it. All I can do is manually "purge" them (by deleting files on /root/.local/share/Trash), but restoring would be very tricky (opening info files and manually moving, etc.).

• For non-/ partitions (or at least for VFAT/NTFS), I can not even use trash as root: it does not create a ./Trash-0 folder, it simply says "Cannot trash, want to permanently delete?" Why?

• About fstab: i use it for a permanent mount for my NTFS partitions. I have several, and if not "pre-mounted" they really clutter the desktop and/or Nautilus. I'd rather have it pre-mounted, integrated in my file system, in mounts like /data , /windows/xp , /windows/vista , and so on, and leave /media and its "mount/unmount" flexibility just for truly removable drives.

So, if Ubuntu/Gnome truly follows the spec, is there any way to fix the root issues and to "emulate" the sticky bit for (at least) my fstab'ed NTFS fixed partitions?