command line – Root Cron job does not run

I have a shell file in /root/crons/ which contains two simple commands which works well if they run separately in terminal. But my cron job which should run every 2 minutes does not run at all. It looks like

# www wordpress backup
*/2 * * * * /root/crons/

can somebody tell me please what could be the problem.
Commands in are here

sudo curl
sudo mv /var/www/kutkovak/wp-content/uploads/backwpup-cd9e2f-backups/* /root/backups/www/kutkovak/

I am new in this so may be it is a trivial problem.

reference request – a square root inequality for symmetric matrices?

In this post all my matrices will be $mathbb R^{Ntimes N}$ symmetric positive semi-definite (psd), but I am also interested in the Hermitian case. In particular the square root $A^{frac 12}$ of a psd matrix $A$ is defined unambigusouly via the spectral theorem.
Also, I use the conventional Frobenius scalar product and norm

Question: is the folowing inequality true
|A^{frac 12}-B^{frac 12}|^2leq C_N |A-B|quad ???

for all psd matrices $A,B$ and a positive constant $C_N$ depending on the dimension only.

For non-negative scalar number (i-e $N=1$) this amounts to asking whether $|sqrt a-sqrt b|^2leq C|a-b|$, which of course is true due to $|sqrt a-sqrt b|^2=|sqrt a-sqrt b|times |sqrt a-sqrt b|leq |sqrt a-sqrt b| times |sqrt a+sqrt b|=|a-b|$.

If $A$ and $B$ commute then by simultaneous diagonalisation we can assume that $A=diag(a_i)$ and $B=diag(b_i)$, hence from the scalar case
|A^frac 12-B^frac 12|^2
=sumlimits_{i=1}^N |sqrt a_i-sqrt b_i|^2
leq sumlimits_{i=1}^N |a_i-b_i|
leq sqrt N left(sumlimits_{i=1}^N |a_i-b_i|^2right)^frac 12=sqrt N |A-B|

Some hidden convexity seems to be involved, but in the general (non diagonal) case I am embarrasingly not even sure that the statement holds true and I cannot even get started. Since I am pretty sure that this is either blatantly false, or otherwise well-known and referenced, I would like to avoid wasting more time reinventing the wheel than I already have.

This post and that post seem to be related but do not quite get me where I want (unless I missed something?)

Context: this question arises for technical purposes in a problem I’m currently working on, related to the Bures distance between psd matrices, defined as
d(A,B)=minlimits_U |A^frac 12-B^frac 12U|

(the infimum runs over unitary matrices $UU^t=Id$)

permissions – Ubuntu 20.04 Startx nome Desktop only running with root

Startx does only work with Root user. A User with the same rights does not work. The same is valid for RDP connection via XRDP. This is only valid for gnome-desktop. If I use anoother desktop environment this problem does not show up.

The error message makes no sense for me. Both files are owned by root which is pretty normal. The user which is calling startx own all files in the home directory.


X.Org X Server 1.20.8
X Protocol Version 11, Revision 0
Build Operating System: Linux 4.4.0-177-generic x86_64 Ubuntu
Current Operating System: Linux 5.4.0-31-generic #35-Ubuntu SMP Thu May 7 20:20:34 UTC 2020 x86_64
Kernel command line: BOOT_IMAGE=/vmlinuz-5.4.0-31-generic root=UUID=810facc8-3144-4ad6-926b-e6350f7e0983 ro
Build Date: 06 April 2020  09:39:29AM
xorg-server 2:1.20.8-2ubuntu2 (For technical support please see
Current version of pixman: 0.38.4
        Before reporting problems, check
        to make sure that you have the latest version.
Markers: (--) probed, (**) from config file, (==) default setting,
        (++) from command line, (!!) notice, (II) informational,
        (WW) warning, (EE) error, (NI) not implemented, (??) unknown.
(==) Log file: "/var/log/Xorg.0.log", Time: Tue May 26 23:51:55 2020
(==) Using system config directory "/usr/share/X11/xorg.conf.d"
/usr/bin/gnome-session: 29: exec: /usr/libexec/gnome-session-binary: Permission denied
xinit: connection to X server lost

waiting for X server to shut down (II) Server terminated successfully (0). Closing log file.

lenovo – How to unmount internal storage as a disk drive no root without pc

I’m very unlucky. At first my sd card got corrupted and than I changed the sd card with another one and then I thought that I would not be able to get my erased data back and I should start from a new start. But afterwards I noticed I was NOT able to see my files in Google Files app I got soo much scared and sad. But few days later I watched a video ‘how to hardreset an android’ I got little happy to see that title but when I started doing that trick, when I checked the recovery mode I literally saw no wipe data/factory option.

I lost my hope but it gets even worse later. I am no longer able to download large files and I can’t download the files that I get from whatsapp (from friends) even if they are like in KBs.(I need those files because they are important as they from my teachers). It says ‘You don’t have enough internal storage. Pls unmount the internal storage as disk drive’

If anyone knows solution to my problem PLS PLS PLS PLS PLSSS help me
I have lenovo tab 4 10 and it is not rooted.(Snap Dragon cpu)

Thank you

grub2 – Ubuntu eoan failure with grub-probe on ZFS root partition

new user here. I tried to install Ubuntu again after a long time and used ZFS as root partition to try it out. Have encountered some issues which manifest when installing software via apt:

user@T440S:~$ sudo apt upgrade
Reading package lists... Done
Building dependency tree       
Reading state information... Done
Calculating upgrade... Done
The following packages were automatically installed and are no longer required:
  linux-headers-5.3.0-42 linux-headers-5.3.0-42-generic linux-image-5.3.0-42-generic linux-modules-5.3.0-42-generic
Use 'sudo apt autoremove' to remove them.
0 upgraded, 0 newly installed, 0 to remove and 0 not upgraded.
2 not fully installed or removed.
Need to get 0 B/8,664 kB of archives.
After this operation, 0 B of additional disk space will be used.
Do you want to continue? (Y/n) 
Setting up linux-image-5.3.0-53-generic (5.3.0-53.47) ...
Processing triggers for linux-image-5.3.0-53-generic (5.3.0-53.47) ...
 * dkms: running auto installation service for kernel 5.3.0-53-generic
update-initramfs: Generating /boot/initrd.img-5.3.0-53-generic
I: The initramfs will attempt to resume from /dev/sda3
I: (UUID=8d9373be-c8cb-4b3d-a6b2-4eb3efc268a5)
I: Set the RESUME variable to override this.
/usr/sbin/grub-probe: error: failed to get canonical path of `rpool/ROOT/ubuntu_qojhyv'.
run-parts: /etc/kernel/postinst.d/zz-update-grub exited with return code 1
dpkg: error processing package linux-image-5.3.0-53-generic (--configure):
 installed linux-image-5.3.0-53-generic package post-installation script subprocess returned error exit status 1
Errors were encountered while processing:
E: Sub-process /usr/bin/dpkg returned an error code (1)

user@T440S:/dev$ sudo grub-probe /
grub-probe: error: failed to get canonical path of `rpool/ROOT/ubuntu_qojhyv'.

I have not been able to figure out why it can’t probe the root pool location. There are some similar questions on AskUbuntu but none exactly like this problem. For example:

This user had similar for seems more related to crypto or snapshots

This one is closer but env var did not fix and struggling with the symlink suggestion because the rpool format shows no where

There are more similar launchpad issues with ubuntu but not sure how to work around:

This seems like a good match… but is old an allegedly fixed long ago

This also seems like a good match… links to another issue

This allegedly is a fix but not sure how to apply it. There are no lines where it tries to use grub_probe

I am not really sure how to resolve the issue at this point.

Any ideas?

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