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21. August 2020

Linux: Turn jpeg images lossless out of Nautilus

Filed under: Linux — Tags: , , , , , , — Christopher Kramer @ 22:13

Your camera does not always turn your images the correct way? You search for an easy way to turn multiple images in linux?

That’s the problem I just came across. And this is my solution:

In Nautilus, the default file manager in Ubuntu Linux and a lot of other linux distributions, you can easily run scripts out of the context menu. All you have to do, is place your script in the following directory:

~/.local/share/nautilus/scripts/SCRIPTNAME

Nautilus will pass the selected files as parameter. So all we need to do, is write a script that turns our image. I was searching for something that can turn .jpeg-images in a lossless way. This means, turning the image won’t reduce the image quality. A good tool for this job is jpegtran, which can be installed like this in Ubuntu:

sudo apt install libjpeg-progs

Now create the file ~/.local/share/nautilus/scripts/jpeg turn 90 with the following content:

#!/bin/bash
for FILE in "$@"; do
        jpegtran -rot 90 -outfile "$FILE" "$FILE"
done

Now you can right-click jpeg files and turn them easily in Nautilus:

You can even select multiple images in Nautilus and turn all of them at once.

Now create jpeg turn 180 and jpeg turn 270 scripts with 180 and 270 after -rot instead of 90 in the script. This way, you can easily turn images by 180 or 270 degrees as well.

If this made your day, please drop a comment.

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2. February 2020

MySQL root password in Ubuntu cannot be changed

Filed under: DBMS,Linux,Server Administration — Tags: , , , , , — Christopher Kramer @ 16:08

You tried a dozen different howtos to change the root password of MySQL (5.7+) in a recent Ubuntu version (18.04+) and did not succeed? Like the one I posted in 2013?

The reason these guides do not work is simple: root access through password is disabled and thus changing the password has no effect. You can find more details here.

So how the heck can we access the database? On the console, you can login to MySQL as root without a password like this:

sudo mysql

If you need root access from another application, like phpMyAdmin, the best way is to add a new user like myroot that has all privileges and a password. To do so, login as root in the console (sudo mysql) and then create the new user like this (adjust new_password to something more secure):

CREATE USER 'myroot'@'localhost' IDENTIFIED BY 'new_password';
GRANT ALL PRIVILEGES ON *.* TO 'myroot'@'localhost' WITH GRANT OPTION;
CREATE USER 'myroot'@'%' IDENTIFIED BY 'new_passord';
GRANT ALL PRIVILEGES ON *.* TO 'myroot'@'%' WITH GRANT OPTION;
FLUSH PRIVILEGES;
QUIT;

Now you can login from any application using the username myroot and the password new_password . On the console:

mysql -u myroot -p
Enter password: new_password

Hope this helps somebody who is in the same situation like me.

If this made your day, please drop a comment.

13. January 2020

TeXworks: Editor Window opens without Titlebar, no way to minimize

Filed under: Linux — Tags: , , , , , , , , , — Christopher Kramer @ 11:33

I was using TeXworks 0.6.2 to edit LaTeX files under Ubuntu Linux 18.04 (using Gnome with X11). Suddenly, a file that I had edited before would always open in a strange way. The preview window with the PDF would open normally. But the editor opened maximized without a titlebar, window border etc. So there was no way to minimize the editor window.

I tried to minimize the window using keyboard commands and the Window-Menu of the TeXworks editor. I managed to move the window to a different screen using keyboard commands, but still maximized without a titlebar. The window menu also did not work. Restarting TeXworks also did not help. Other files would open normally.

What finally helped: File / Remove Aux Files…
Afterwards, restart TeXworks.

I did not know that TexWorks stores window status information in aux-files. But it seems it does, as deleting these files solved the problem.

If this tip saved your day, please drop a comment. This motivates me to keep writing these kind of posts.

4. December 2019

letsencrypt certbot: how to remove some domains from an existing certificate

Filed under: Linux,Server Administration — Tags: , , , , — Christopher Kramer @ 21:44

You have a certificate with a couple of alternative domain names added to it, but want to get rid of some of them while keeping others? The parameter --renew-with-new-domains is what you want. This is how you use it:

certbot certonly --cert-name "maindomain.com" --renew-with-new-domains -d "maindomain.com,alternative1.com,alternative2.com"

This will renew the certificate maindomain.com with the domains maindomain.com, alternative1.com and alternative2.com. Any other domains that had been included in the certificate before will not be included in the new certificate. If you execute it like this, it will ask you for the verification method and parameters interactively. Alternatively, you can also configure this with parameters like -a webroot --webroot-path "/var/www/” .

24. August 2018

Clementine Music Player needs to be started twice, no window on first start

Filed under: Linux — Tags: , , , , , , , , — Christopher Kramer @ 15:01

clementine music player logoIn Ubuntu 18.04, I start Clementine Music Player, but no window is coming up. But once I start Clementine another time, it comes up.

This is not a bug, it is a setting. So this is what you want:

Tools -> Preferences -> Behaviour -> When Clementine starts -> Always show the main window

No, you are not alone, it is you, me, and a bunch of other people.

17. July 2018

Debian Stretch: Adjust the CPU priority (nice level) of systemd daemons like spamassasin, amavisd-new, clamd etc.

Filed under: Linux,Server Administration — Tags: , , , , , , , , , , , — Christopher Kramer @ 20:17

The good old days: init.d

When still using Debian Wheezy, I configured my spamassasin service to run at a nice level of 10 so it does not slow down apache, mysql, php etc. To do so, I noticed in /etc/init.d/spamassasin a parameter called NICE with a comment saying I should not touch this and instead, go into /etc/default/spamassassin. So I adjusted this file, and on my Debian Stretch, it still looks like this:

 

# /etc/default/spamassassin
# Duncan Findlay

# WARNING: please read README.spamd before using.
# There may be security risks.

# Change to one to enable spamd
ENABLED=1

# Options
# See man spamd for possible options. The -d option is automatically added.

# SpamAssassin uses a preforking model, so be careful! You need to
# make sure --max-children is not set to anything higher than 5,
# unless you know what you're doing.

OPTIONS="--create-prefs --max-children 5 --helper-home-dir"

# Pid file
# Where should spamd write its PID to file? If you use the -u or
# --username option above, this needs to be writable by that user.
# Otherwise, the init script will not be able to shut spamd down.
PIDFILE="/var/run/spamd.pid"

# Set nice level of spamd
NICE="--nicelevel 10"

# Cronjob
# Set to anything but 0 to enable the cron job to automatically update
# spamassassin's rules on a nightly basis
CRON=1

 

This had worked well on Debian Wheezy. Now I noticed that on Debian Stretch, the spamassasin service is running with a nice level of 0, so basically this has no effect. This is because Debian now uses systemd and these init.d files are magically transformed into systemd units and there, the nice level cannot be adjusted like this. The complete story is a lot longer and complex, but I don’t want to bother you here.

How to adjust the nice level of services on Debian Stretch

First, check the location of the unit file of your service. To do so, run:

systemctl status spamassassin.service

It will output something like:

● spamassassin.service - Perl-based spam filter using text analysis
   Loaded: loaded (/etc/systemd/system/spamassassin.service; disabled; vendor preset: enabled)
   Active: active (running) since Tue 2018-07-17 16:07:26 CEST; 19min ago
 Main PID: 946 (/usr/sbin/spamd)
    Tasks: 3 (limit: 4915)
   CGroup: /system.slice/spamassassin.service
           ├─946 /usr/sbin/spamd -d --pidfile=/var/run/spamd.pid --create-prefs --max-children 5 --helper-home-dir
           ├─949 spamd child
           └─950 spamd child

Jul 17 16:07:23 systemd[1]: Starting Perl-based spam filter using text analysis...
Jul 17 16:07:26 systemd[1]: Started Perl-based spam filter using text analysis.

 

In the line “Loaded”, it gives the location of the unit file, in this case:

/etc/systemd/system/spamassassin.service

In your case, it is probably:

/lib/systemd/system/spamassassin.service

If it gives the path to /etc/init.d/ and says “generated” under loaded, as it does e.g. for amavisd-new, then you will probably find the unit file automatically generated by systemd-sysv-generator in one of these paths:

/run/systemd/generator.late
/run/systemd/generator.early
/run/systemd/generator

If your unit file is not already in etc, copy the file from where it is now to /etc, e.g. like this:

cp /lib/systemd/system/spamassassin.service /etc/systemd/system/

If your file is already in /etc, then just go ahead and edit this.

Now open the file /etc/systemd/system/spamassassin.service – it will look like this:

[Unit]
Description=Perl-based spam filter using text analysis
After=syslog.target network.target

[Service]
Type=forking
PIDFile=/var/run/spamd.pid
EnvironmentFile=-/etc/default/spamassassin
ExecStart=/usr/sbin/spamd -d --pidfile=/var/run/spamd.pid $OPTIONS
ExecReload=/bin/kill -HUP $MAINPID
StandardOutput=null
StandardError=null
Restart=always

[Install]
WantedBy=multi-user.target

Now adjust it so after [Service] and before [Install], it sets the nice level like this:

[Unit]
Description=Perl-based spam filter using text analysis
After=syslog.target network.target

[Service]
Type=forking
PIDFile=/var/run/spamd.pid
EnvironmentFile=-/etc/default/spamassassin
ExecStart=/usr/sbin/spamd -d --pidfile=/var/run/spamd.pid $OPTIONS
ExecReload=/bin/kill -HUP $MAINPID
StandardOutput=null
StandardError=null
Restart=always
Nice=10

[Install]
WantedBy=multi-user.target

 

Now reload the systemd-daemon:

systemctl daemon-reload

And restart your service:

systemctl restart spamassassin.service

Now check the nice level of your spamd processes, it should be 10 now.

 

If this made your day or you still have problems, please let me know in the comments.

9. June 2017

Automatically run WP-CLI as the correct user

Filed under: Linux,Server Administration,Wordpress — Tags: , , , , , , — Christopher Kramer @ 19:04

You are root, your php runs with a different user for each site / customer e.g. using PHP-FPM. And these users don’t have a shell assigned. So how can you easily run wp-cli with the correct user to avoid permission denied-problems?

This is how: Define an alias for wp in your shell config, e.g ~/.bash_profile like this:

alias wp='sudo -u `stat -c '%U' .` -s -- php /usr/local/wp-cli.phar --path=`pwd` '

This will first run stat -c %U . to get the owner of the current folder. Then it will pass this to sudo to execute the command as this user. You might need to adjust the path to the phar-file.

Relogin so the alias takes effect and have fun! 🙂

Now when you are in the folder of some site and run wp-cli with the wp command, it will always automatically run with the user that is the owner of the wordpress-folder, which should be the user assigned to this site.

This is tested on a Debian Wheezy system. On FreeBSD, you would need to adjust it slightly:

alias wp='sudo -u `stat -f '%Su' .` -s -- php /usr/local/wp-cli.phar --path=`pwd` '

Let me know if this saved your day or you still have some problems.

17. August 2016

Linux Software Raid: Enlarge Raid Array of Hetzner EX41

Filed under: Linux,Server Administration — Tags: , , , , , , , , — Christopher Kramer @ 21:15

Recently, I ordered an EX41 server at Hetzner, which by default comes with two 4 TB HDDs in a software RAID1. I chose the minimal Debian Jessie Image. From Hetzner’s EX40, which has two 2 TB drives in a Software RAID1, I was used to find the whole drive formatted as one partition by Hetzner. But with the EX41, it turned out that the 4 TB were split: The root partition / was 2 TB of size and 1.7 TB were allocated to /home. As the application that should run on this server needs more than 2 TB space in one folder, I repartitioned the server. If somebody else has a similar issue, here is how it can be done:

  1. Edit /etc/fstab and remove or comment (by placing a # at the beginning) the line that mounts /home from /dev/md3
  2. Reboot into the Rescue system or some other system that is not on the same drive. (The Hetzner rescue system boots from network. On a local system, you would boot a linux from CD or USB.)
  3. Check the Raid status and setup: 
    cat /proc/mdstat

md3 : active raid1 sda4[0] sdb4[1]
      1777751872 blocks super 1.2 [2/2] [UU]
      bitmap: 0/14 pages [0KB], 65536KB chunk

md2 : active raid1 sda3[0] sdb3[1]
      2111700992 blocks super 1.2 [2/2] [UU]
      bitmap: 0/16 pages [0KB], 65536KB chunk

md1 : active raid1 sda2[0] sdb2[1]
      523712 blocks super 1.2 [2/2] [UU]

md0 : active raid1 sda1[0] sdb1[1]
      16760832 blocks super 1.2 [2/2] [UU]

    So here md3 is the raid array that we want to get rid of together with its partitions sda4 and sdb4. md2 the raid array that we want to grow in size.

  4. First let’s get rid of the md3: 
    mdadm --stop /dev/md3
mdadm --zero-superblock /dev/sda4
mdadm --zero-superblock /dev/sdb4
parted /dev/sda rm 4
parted /dev/sdb rm 4
  5. Resize the partitions of md2 (sda3 and sdb3):
    (Adjust the end if necessary)

    parted /dev/sda
(parted) resize 3
(END?) 4000GB
(parted) quit

parted /dev/sdb
(parted) resize 3
(END?) 4000GB
(parted) quit

    Note: Tomas pointed out in the comments that the resize-command was removed and replaced with resizepart in current versions of parted. So the command is now:

    parted /dev/sda
(parted) resizepart 3 4000GB
(parted) quit

    (then do the same for sdb)

  6. Let the raid array md2 grow: 
    mdadm --grow /dev/md2 --size=max
  7. Check the raid status: 
    cat /proc/mdstat
Personalities : [raid1]
md2 : active raid1 sda3[0] sdb3[1]
      3888815376 blocks super 1.2 [2/2] [UU]
      [===================>.]  resync = 97.8% (3807048128/3888815376) finish=13.3min speed=101952K/sec
      bitmap: 1/15 pages [4KB], 131072KB chunk
  8. Wait until the resync finished (took a few hours for 2 TB): 
    cat /proc/mdstat                                                                                                                                        
Personalities : [raid1]
md2 : active raid1 sda3[0] sdb3[1]
      3888815376 blocks super 1.2 [2/2] [UU]
      bitmap: 0/15 pages [0KB], 131072KB chunk
  9. Check the filesystem: 
    e2fsck -fv /dev/md2
  10. Resize the filesystem: 
    resize2fs /dev/md2
  11. Reboot into your normal system and you are done: 
    reboot
  12. Check the free disk space: 
    df -h

    It should give the new size of / (3.6 TB) and a lot more free space 🙂

Hope this helps somebody with the same or similar issue.

 

28. June 2016

flashplugin-installer cannot download files using unattended-upgrades on Ubuntu

Filed under: Linux — Tags: , , , , , , — Christopher Kramer @ 10:29

Using unattended-upgrades on Ubuntu  16.04 (and previous versions) set up to install updates on shutdown, flashplugin-installer always failed when downloading the new version. The reason probably is that on shutdown, the Internet connection is not available anymore. Up to now, I always updated flashplugin-installer manually. But today, I found a nice and simple solution:

Just get rid of the installer! In the Cononical partner repository, there is a package that directly contains the flash plugin. First, make sure you include the partner repository in your /etc/apt/sources.list, e.g. for xenial:

deb http://archive.canonical.com/ubuntu xenial partner
deb-src http://archive.canonical.com/ubuntu xenial partner

Then, update, get rid of the flashplugin-installer, and install the adobe-flashplugin instead:

sudo apt-get update
sudo apt-get remove flashplugin-installer
sudo apt-get install adobe-flashplugin

Hope this helps someone who also has problems with unattended upgrades and falshplugin-installer.

17. June 2016

Multimedia Keys “stuck” after Ubuntu 16.04 upgrade

Filed under: Linux — Tags: , , , , , , , — Christopher Kramer @ 21:19

After upgrading Ubuntu Gnome to 16.04, the multimedia keys / extra keys (like play/pause, volume up/down, mute, calculator, forward, backward, etc.) of my old Cherry G86-21050 DEAAAA keyboard showed a strange behavior: Whenever one of the buttons was pressed, its effect was repeated over and over, just as if the button was stuck. So pressing pause would play and pause the song over and over, pressing calculator would open hundreds of calculator windows. Pressing another special keys stopped the previous effect from repeating, but repeated the effect of the last special key over and over. The normal keys (letter, numbers etc.) were not affected.

As the effect appeared after the upgrade for all special keys, I was sure it was a software problem and not a hardware problem.

Digging around with evtest (no, it is not a good idea to run evtest –grab on your keyboard in a tty :D), I found out that the key events are not repeated multiple times, but the keys are not released.

Annoyed, I tried another keyboard (Logitech Elite Keyboard) for comparison. The special keys of that one worked well.

Finally, I accidentally plugged the “faulty” Cherry Keyboard in the USB port that I had the working Logitech in between and voila: The Cherry’s special keys worked again.

So lesson learned: Have you tried plugging it out and in again? Is the first question you should ask (yourself) whenever some USB device behaves strangely.

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