When tarring a file, even if the process (Nice) priority is low, sometimes the IO will make the computer unusable, so what you can do it ask Linux to only work on the IO intensive job when there is no other application requiring IO
ionice -c 3 -p $PID
The above class (3) means only if no other application is using this disk
The answer is, depending on your needs, but you are not here to hear that now are you, so I did a little experiment, tailored specifically for a certain need that does not apply accross the board, but combined with other experiments online, this might give you an idea
The experiment is annotating an image with image magic plugin for PHP
Both running buster (Debian/Raspbian 10), both on PHP7.3 and everything fresh installed
the PC has 8GB of DDR3 Ram, and the PI 1GB of LPDDR2-900 SDRAM
The PC has a 12 year old “Intel(R) Core(TM)2 Quad CPU Q9450 @ 2.66GHz”
The PC was around 7 fold faster than the raspberry PI 3 (the mean of a trial of 20 runs, with all the files cached in ram by the linux kernel)
The trial was done with a discrete VGA card (AMD RADEON) and with the chipset’s own graphics card, results were identical (The VGA card did not have it’s drivers installed, so we don’t know if it might have an effect or not)
I am now moving into even older PCs to compare performance, and will report the results here again to see what the limiting factors might be
Usually, i go with a serial cable, these days, people have found simpler ways
Start by downloading lede-17.01.5-ar71xx-generic-tl-mr3220-v2-squashfs-factory.bin from the openwrt website (Don’t use the original, it needs trimming 😉 and you can install it after using the post after this one
rename the file you downloaded to mr3220v2_tp_recovery.bin and put it in your tftp client folder
Setup your computer’s LAN settings to the IP address 192.168.0.66
Connect the eithernet cable to the yellow LAN port farthest away from the blue wan port (Not the one next to it, only this port works)
start your TFTP client, pick your eithernet LAN and connect the lan cable
Hold the WPS/Reset button, and while holding it, start the router, then wait 4 seconds and release it
On your screen, you should see your TFTP client sending a file (on tftpd32 you see a download progress bar)
Wait for the router to reboot, now you have hte openwrt firmware, go ahead and read the previous post on going back to factory 😉
Have a great day
If you are on openwrt and want to revert back to factory firmware, you need to do the following easy steps
Download the file from the tp-link website, this should be straight forward, you go to the website, search for your router by model, on the firmware download page, select the version of your router and download the file
If it is a zip file, extract it, we are looking for a bin file that should be inside the zip file (Make sure it has up_boot in the file name)
Use an application such as putty to connect to the router as root, and an application such as winSCP to connect to the router (Also as root) to upload the file
upload the file to the /tmp folder, this folder is in RAM not on the flash of the router, so it has more space that can accommodate the procedure
Using Putty, execute the following commands
cd /tmp
On this command here, you will need to replace the name of the file with the name of the file you have uploaded to the router
This command (That starts with DD), trims the first 257*512 = 131,584 bytes from the file which are the boot loader
dd if=yourfilename.bin of=flash.bin skip=257 bs=512
Now you would want to remove the old file after we have trimmed it with DD
rm yourfilename.bin
Now, to the final step, which is actually writing the trimmed firmware to the router
mtd -r write /tmp/flash.bin firmware
Now all you need to do is wait for the router to write the firmware, right after it will reboot and you are done
Well, to make a long story short, I make large scans that don’t need to be on my system disk, I would like to have them stored on the spinning disk, So, i searched online, and found that people were suggesting that I create a symlink to the new location in place of the Scanned Documents folder, Something like
mklink /d "C:\Users\yazeed\Documents\Scanned Documents" D:\scanner
The above obviously has downsides, backup software, changed disk IDs, or other unforeseen effects, In my mind, there is no way the developers of Windows Fax And Scan have hard coded this into the application,
Another solution would have been to move the entire Documents folder (Right click it, then change it’s location, windows provides that option), But not everyone wants that, So there is a third more elegant solution (Even though this works like a charm)
The third is to look in the registry (Find) where Windows Fax And Scan stores it’s path (Look for the word scanned for example), and change that, but i Have already gone with the second, the third should be simple
The setup assumed in this post is as follows, you are working on a remote windows computer, there is a Linux KVM host computer running guest virtual machines somewhere (OS of guest irrelevant), and you would like to connect to a guest machine’s console (which may be running windows, linux, macOS, or any operating system)
KVM, by default only allows people to connect through VNC to the console of a virtual machine if they are using the local host computer, so here are the tips on creating a tunnel to the host computer and connecting to your KVM virtual machine.
Windows does not support VNC very well, (Most VNC servers don’t run well on windows), but the VNC server here is not windows, it is KVM that is providing the VNC server to the guest’s console.
1- Create a tunnel (Putty on windows), simply put, save the connection in putty to that host machine, then under tunnels you will need to have something like this (And go back and hot save again)
Just create a tunnel for port 5900 and the destination localhost:5900 (5901 for the second virtual machine and so on), leave all other tunnel options unchecked/default
2- to know which ones are enabled on your machine run this command
netstat -tlpn | grep 590
3- VNC should now connect to localhost:9500 for example (I am using tightVNC on windows), and that connection should be automatically router to the KVM host, which will display the guest’s console depending on the port (every guest has it’s own port)
The lowdown, applying grease to the fan pin works, no idea for how long (Already ordered a replacement fan from the HP website just in case), but when this fan fails, I will certainly update this post (Today is April 18, 2020).
The only reason i use my HP Envy 17-s143cl which has a slow I7-7500U (X0S43UA) is because it is silent most of the time, and quiet when the fan eventually spins up, not any more, today, the fan was very loud, and vibrates heavily, sometimes banging above the fan resolved it (Don’t try if you have a spinning disk, you will damage it, I have an SSD inside so it is okay).
So i took the laptop apart, extracted the fan, opened the fan casing, and then the plastic fan separates from the coil by simply pulling it out (With very little force, if you need any force you are doing it wrong).
So, like you see in the photos above, I applied some automotive lithium grease to the pin, and put everything back how it was, the fan is working very smoothly, just like before, if it fails and that is a good possibility, I will update this post, but for now, it looks like a hit
Also worth mentioning is that i usually add such lubricant to PC fans, the cheap $1 fans, they usually need the lubricant after a few months, but after adding the lubricant under the back sticker on a desktop PC fan, they usually work for years more without problems, so I expect this to not give me any trouble, but in any case, I have already ordered a replacement just in case, turns out the HP store is cheaper than ebay and amazon, Just go to HP and find the part you need, mine was the one below. it cost me with shipping an all around 32 US dollars.
806747-001 In stock
FAN – for Broadwell SKU (Fanless design for Braswell SKU)
RoHS: COMPLY_2.05
| Order subtotal | 18.26 |
| Shipping and Handling | 11.25 |
| Tax | 2.62 |
| Order total (USD) | 32.13 |
In short, You can (Up to date systems) mount it in 1 go with something like
mount -o loop /path/to/my-iso-image.iso /mnt/iso
Step 1, what is the next loop number we can mount on ?
losetup -f
This will probably result in something like /dev/loop0 (Which is the next ready loop to map the ISO to
losetup /dev/loop0 /path/file.isoThen, mount the loop device with the mount command
mount /dev/loop0 /mnt/dirThat’s it, The new solution and the old, As always, i keep things here as a not to self, because sometimes I come across older computers, and I forget how it was done since all the mounting I do now the new way
In this post, I will be explaining how to watermark videos with a PNG image watermark that is transparent where it needs to be, I will cover both Linux and Windows (Not much is different on the ffmpeg side, the difference is when you want to traverse a directory (The script).
The watermark you see here is what I want to overlay over the video, If you right click and view the image, you should be able to see that around the text, it is transparent.
now, let us assume that the file in the directory is called x.mp4, and this watermark image is called watermark.png, then the following commands should overlay this image over the video
ffmpeg -i x.mp4 -i watermark.png -filter_complex "overlay=10:10" x1.mp4
The code above will create a new file (x1.mp4) which has the overlaid watermark, as you might be able to see if you execute the above the watermark is positioned at the top left corner of the video, which is not necessarily what you want, now because we know the dimensions of the watermark image, we can ask ffmpeg to center it horizontally (and if you like vertically to have it in the center of the image, but this is not what i want.
So let’s assume the video is full HD, meaning it has the dimensions 1920 x 1080 (Width x Height), and the image, as you can see has the dimensions (500 x 100), what i want here is to have the watermark centered horizontally and nudged down 100 pixels vertically, the code to do that would be
ffmpeg -i z.mp4 -i watermark.png -filter_complex "overlay=x=(1920-500)/2:y=100" z3.mp4
And in case this is not clear, here is a code to place it in the bottom right side of the screen
ffmpeg -i z.mp4 -i watermark.png -filter_complex "overlay=x=(1920-500):y=(1080-100)" z6.mp4
Now with the process of watermarking out of the way, How do we batch process videos under windows and under linux ?
Under Linux it is simple, I put all the input files in a directory named “in” and all the output is to be put in an directory called “out”, the shell script (batch file) is at the root where those 2 directories exist, the shell script is this
!/bin/bash OIFS="$IFS" IFS=$'\n' for filename in "in/"*.mp4; do ffmpeg -i "$filename" -i /apth_to_watermark/watermark.png -filter_complex "overlay=x=(1920-500):y=(1080-100)" "out/$(basename "$filename" .mp4).mp4" done IFS="$OIFS"
I have never been good at windows, so i looked around for a script to traverse a directory, I found some stuff, and here is my final result, if you can clean it up and make it more robust, please do leave me a comment and i will improve with your recommendations.
I have a certain setup with a Varnish5 caching reverse proxy, with nginx to terminate SSL connections.
The problem with this setup is that wordpress can’t detect https, hence, it can not enforce it, nor will it link the CSS accordingly etc…, and if your blog’s address starts with https, you have a problem.
there is more than one solution that i will enumerate here, I chose to force all connections to come through https (The first), but there are others, the one i will present here (Which i did not use) resolves the problem and allows wordpress to detect whether we are on a secure connection or not.
And even though this post-article talks about wordpress, everything here can apply to any PHP application (Or even other applications written in different programming languages)
1- Enforce https for the whole website
The simplest way to solve the problem (Which i chose) is to redirect all traffic to https.
in the varnish script, implement the following
in the sub vcl_recv, implement the following
if (req.http.host ~ "^(www\.)?example\.com$")
{
if (req.http.host ~ "^(?i)example.com" || req.http.X-Forwarded-Proto !~ "(?i)https") {
return (synth(750, ""));
}
}
Now, the following section is the sub vcl_synth
sub vcl_synth {
if (resp.status == 750) {
set resp.status = 301;
set resp.http.Location = "https://www.example.com" + req.url;
return(deliver);
}
}
Once the above is in place in the varnish script, You will need to tell wordpress that it’s all HTTPS (SSL)
We do that in the config file, the only file we know that does not change when we update
define('FORCE_SSL_ADMIN', true);
$_SERVER['HTTPS']='on';
Now, the above should do it if you don’t mind that your website only works in https, if you do want http to remain an option, then here is another solution
Start by creating a phpinfo() page to check whether you have the $_SERVER[‘HTTP_X_FORWARDED_PROTO‘] variable , if you do, your work is partially done, but you need to mind too things
the varnish server needs to only cache the https copy (because most browsers won’t allow mixed content these days, and if the css is linked to as http, it won’t display correctly), you can do that easily with something like the following in the vcl_hash area
if (req.http.X-Forwarded-Proto) {
hash_data(req.http.X-Forwarded-Proto);
}
And then, also in the wp-config file, add the following (probably almost anywhere)
if ( isset( $_SERVER['HTTP_X_FORWARDED_PROTO'] ) && $_SERVER['HTTP_X_FORWARDED_PROTO'] == 'https')
$_SERVER['HTTPS']='on';