Questions tagged [dev]

The Linux/Unix /dev directory contains the special device files for all the devices.

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11 views

How to find /dev/video or similar for USB camera

I have a USB camera plugged in and want to find the device file on macOS.  Something like /dev/video0.
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Using /dev/tcp in Bash script to send a POST request to RESTful API and process the result in json

I am using bash script to send POST request to RESTful API and would process the result in json. (curl, netcat wget are not available...) POST request should be in FORM and the API will return with a ...
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Writing to /dev/sdX instead of /dev/sdX1

What happens physically if I want to copy some files to an external hard drive and do cp -a [file] /dev/sdX instead of cp -a [file] /dev/sdX1? Or when wiping a drive by overwriting it with zeros, is ...
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442 views

/dev/ttyACM0 lost after sleep - How to redetect / restart / rescan for ttyACM0?

I have a Ubuntu 16.04 based VM which runs inside VirtualBox on Windows 10. On my Host, I've connected a ZWave USB antenna, which I've then mapped/attached to the VM. When I first boot my VM, I can ...
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v4l2 loopback installation on coral dev board

I am trying the edgetpu object detection examples for the coral dev board. https://coral.ai/docs/dev-board/camera/ I would like to draw the video stream from rtsp instead of /dev or an .mp4 file. ...
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Finding .npm debug logs in Azure DevOps Pipeline

I have an existing build pipeline for a Vue web app that has worked flawlessly for over a year now up until today. I'm not a devops guy so I don't understand it 100% and got thrown into this, but here ...
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1answer
917 views

What is the difference between “mount -t …” and “mount -o bind …” with regard to chroot environment

So I am setting up a chroot where I need proc, sys and dev folders. I have read that I need to mount them as follows: mount -t proc /proc /mnt/chroot/proc mount -t sysfs /sys /mnt/chroot/sys mount -...
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1answer
86 views

Consistent USB device adapter naming on Linux

I have a USB port into which I insert all sorts of different USB disks over time. The kernel does not consistently allocate the same device for it, so I have to go hunt after each insert. How can I ...
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2k views

Merge with Jenkins using pipeline

I try to merge branch ( master <-- newBranch ) with Jenkinsfile (pull request trigger) without conflict. When the Jenkins finishes running I get an error message on step3: "fatal: There is no ...
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1answer
113 views

USB Drive not recognized under /dev

I was reading/learning about partitioning, creating file-system, etc. and wanted to do some practical. So i booted my CentOS installed on my windows laptop using Virtual Box and inserted a blank usb ...
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607 views

Running 'cat /dev/urandom > /dev/audio' does nothing

I am trying to have some fun by playing some random audio using /dev/audio under Ubuntu 17.10. The command cat /dev/urandom > /dev/audio executes successfully but it outputs absolutely nothing to ...
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Detected devices name

I am using the Barebox bootloader to boot into an embedded system. I am wondering why some SD-card of mine shows up as 2 devices /dev/disk0.0 /dev/disk0 And sometimes another SD card it shows only ...
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Linux, GSM, nmcli - working with two GSM Modems and connections

I have a following situation. I have two USB modems (one Huwawei LTE modem, one ZTE 3G modem) with two different SIM cards from two different providers (orange and play to be specific). Using ...
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1answer
4k views

Device /dev/spidev* not found

I have a Banana Pi M1 and wanted to flash libreboot on a ThinkPad T400. I followed Raspberry Pi (ThinkPad X200), as RPi's GPIO pins are almost the same as BPi's and T400's chip is the same as X200. ...
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how do I figure out where a usb controller is in /dev?

This is a linux question, how do I figure out where a usb controller is in /dev? I have tried doing ls /dev > before.txt ls /dev > after.txt diff before.txt after.txt pluging the device in when ...
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1answer
3k views

How to clear /dev/dm-0

I noticed /dev/dm-0 is using almost all my HDD space: $ df -h [...] /dev/dm-0 227G 207G 8,8G 96% / [...] I believe /dev/dm-0 is some kind of cache for mounted filesystem (It is the ...
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dd aplied to dev USB before connect corrupt /dev/sdX and dont work

I have a USB where I'm coping an ISO of 5 Mb aprox with a small OS with its own grub. If I connect the device and check it sudo fdisk -l I get: ... Device Boot Start End Sectors Size Id Type /...
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635 views

How to Access `/dev` From Inside a `chroot` Jail?

     How can one access /dev from within a chroot jail? I'd like to know how to do this on OS X v10.11.5 'El Capitan,' in particular. I've already tried to create an ...
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78 views

Attached devices change /dev/sd value

I have a script which auto mounts my Windows partition based on UUID, reason: my attached devices change their /dev/sd value. After booting up, my external hard drive might take on /dev/sda or /dev/...
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276 views

How can I get a Git repo to push/pull when the Git server is behind a firewall?

My work place currently has a gitlab server behind their corporate firewall and currently their public dev sites are facing the internet. I can access the gitlab server only when I'm on their vpn. I ...
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1answer
1k views

Detecting new USB devices with bash?

I'm writing a bash script that needs to detect when a usb storage device is inserted and assign it to a variable that would otherwise, typically look something like: usb=/dev/sdb. I have a few ...
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444 views

How can I set device mode via networkd

How can I set mode to device (for example monitor/ap to wlan) via networkd deamon in .link file ??? Because I want to set bridge in .network of wlan device and I can't do it until I set it in ...
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4k views

v4l2 Identifying /dev/video* via lsusb

I'm writing a script that must use a particular camera plugged in to my system. $ lsusb|grep C930e Bus 001 Device 011: ID 046d:0843 Logitech, Inc. Webcam C930e How can one programatically discover ...
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328 views

creating linux device files for bootstrap

I'm currently independently researching device files as a part of learning more about the Linux system in depth. My current goal is to bootstrap Debian Linux through cdebootstrap. I followed the guide ...
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1answer
693 views

rsyslog.conf: kern.err /dev/console. Where do these messages go?

There is a commented line in rsyslog.conf: #kern.* /dev/console If I add this line to the configuration file: kern.notice /dev/console Where do these messages go? If I run this ...
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1k views

Why do loop devices sometimes refuse to go away?

I regularly mount the partitions inside an image file as loop devices: sudo kpartx -a test.img That creates loop devices such as /dev/mapper/loop0p1 /dev/mapper/loop0p2 When I'm done, I get rid of ...
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761 views

Can the contents of /dev/disk0 (/dev/sda, etc) be used as stdin?

I'm learning about the /dev filesystem. I've begun with /dev/sd* (Linux) and /dev/disk* (OS X), and I've found some interesting behaviour. If I run: $ sudo xxd -l 1024 /dev/disk0 I get the following ...
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1answer
625 views

Not quite grasping /dev/random and /dev/urandom

I am not quite understanding the difference between /dev/random and /dev/urandom on Linux systems. What does it mean to run out of “entropy” and how does the system get more? What does it mean when ...
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12k views

How is by-id created on Linux?

Sticking a USB-microcontroller on the port (similar to Arduino) creates these two files: /dev/serial/by-id/usb-MBED_MBED_CMSIS-DAP_10105a42e87da33c103dccfb6bc235360a97-if01 /dev/disk/by-id/usb-...
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1answer
73 views

Drive assignments changing

I have an Ubuntu 14.04 Server machine set up with 3 drives: Two 2TB HDDs, and a 4GB USB drive for system. It seems that every time I boot the system it changes what drives are assigned to /dev/sd(a/b/...
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1k views

Micro SD impossible to modify (write or format)

Recently i had problems with my SD card used for my android device, basically i cannot modify it (write or format). Only read it, if i try format or write, any time that connect and fisconnect from ...
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1answer
500 views

Cat to /dev/audio not working

I downloaded some files and am trying to cat them to /dev/audio (for fun of course, I'm sure I could just play them) and I guess this is supposed to work, but it doesn't? I get permission denied and ...
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1answer
1k views

Can't mount external HDD. Device listed at lsusb but doesn't appear at /dev

Device works at Windows but doesn't appear at /dev. How can I mount it? So let's go to the infos... uname -a: Linux deeptought 3.13.0-30-generic #54-Ubuntu SMP Mon Jun 9 22:45:01 UTC 2014 x86_64 ...
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2answers
969 views

/dev/dsp missing in debian and cannot hear festival utterance

Tried to make an utterance in festival and it seems /dev/dsp/ is missing in the debian. How to add this? festival> (SayText "Hello") Linux: can't open /dev/dsp #<Utterance 0xb669c708>
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1answer
201 views

Can't recongnize my SSD device file in /dev

I am using Ubuntu and can't find my SSD device file. The /dev directory has following contents: agpgart audio audio1 audio2 audio3 audioctl char console core dsp dsp1 dsp2 dsp3 fd full kmem kmsg log ...
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209 views

Why does the /dev directory exist?

In Linux, there is the /dev directory, which is a special directory which contains all of the files for devices and other things like random, urandom, etc. Why did this directory exist? Was it just ...
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265 views

Does unplugging a disk from linux change disk name after restart?

I had 5 disks (sda, sdb, sdc, sdd, sde) sda is being used for root and boot. sdc,sdd and sde disks are being used by lvm. We unmounted and unplugged the sdb, now I need to restart the server. I am ...
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1answer
481 views

Hauppauge HD PVR 2 to ffmpeg on OS X

How can I use ffmpeg to capture video and audio from a Hauppauge HD PVR 2 connected to my Mac via USB? I have seen a couple posts here and here about doing this on a Unix machine (not OS X) using ...
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1answer
3k views

Disable device node using udev (/dev/sr0)

I am trying to disable udev from generating /dev/sr0 device (my cdrom) and Im trying to write udev rules. I added a file 10-cd-trial.rules in /etc/udev/rules.d and /lib/udev/rules.d, the contents are:...
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Partition Not Showing up in /dev

I recently unmounted a 4TB hard drive from one computer in order to access the files directly from another computer. It seemed like there were no problems with the unmounting process. When ...
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2answers
202 views

How to move /dev/random to another drive on a server

We found a bottleneck in our server (hosted on HDD) related to the /dev/random function. We want to have the OS use the /dev/random that is on our SSD drive rather than the HDD. How can we have the ...
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Why does `cat /dev/urandom` break your terminal?

In reference to this question: https://serverfault.com/questions/534449 How does cat /dev/urandom make some terminal emulators go wonky?
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Why is “/dev/rdisk” about 20 times faster than “/dev/disk” in Mac OS X

According to the rasbery pi documentation, You can load your OS to a flash card with either /dev/disk or /dev/rdisk. rdisk stands for raw disk. /dev/disk is a block level device, why would rdisk ...
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1answer
190 views

What is /dev/blog?

I have tried searching for /dev/blog on google, duckduckgo, etc.; but I cannot find any information about it. I've also asked another sysadmin where I work, but he didn't know what it is used for ...
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1answer
943 views

Ubuntu Drive Mount Order

I have two drives, a 120GB SSD and a 2TB HD. I set the BIOS to boot from the SSD, and an the Drives window of Ubuntu it tells me the SSD is SDB and the HD is SDA. I would expect the SSD to be SDA ...
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1answer
12k views

Is there a device file in the /dev directory that represents the wireless adapter?

I've been exploring the /dev directory and am curious are all the devices mapped to those files there? Specifically I'm looking for a wireless file. I was hoping to find something like /dev/wifi or /...
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USB pen drive not getting assigned anything in /dev/

dmesg | tail -f: [17597.228060] usb 1-1.3: new high-speed USB device number 11 using dwc_otg [17597.330548] usb 1-1.3: New USB device found, idVendor=18a5, idProduct=0300 [17597.330580] usb 1-1.3: ...
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1answer
69 views

what's the easiest way to match up /dev/sdx with a device mounted in /media?

I can never remember which device is what so when it comes to partitioning, etc. I'm afraid of messing up the wrong drive. Automounted devices like external drives don't seem to turn up in fstab. So ...
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1answer
1k views

Mount TMPFS instead of ro /dev

I am working on a ARM-Based embedded system with a custom Debian Linux based on kernel 2.6.31. In the final system, the Root file system is stored as squashfs on flash. Now, the folder /dev is created ...
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2answers
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What's '2>&1' and '/dev/null'

I have been browsing through scripts and see 2>&1 & /dev/null everywhere. What are they? After googling, is it different for OS X than for Linux?