Questions tagged [linux]

These questions are about Linux in general -- NOT specific to a particular distribution. If the question just happens to be in a Linux environment, please specify your Linux distribution in the body of your question, but do NOT use the /linux tag.

6,484 questions with no upvoted or accepted answers
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15
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1answer
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Scrolling with a WACOM tablet pen

I've got a wacom pen with a button. How can I trigger scrolling when moving the pen with the button pressed? According to xev, below, the triggering events are MotionNotify with state 0x200. If this ...
11
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1answer
917 views

ACPI group/action undefined: processor / LNXCPU

If I unplug my laptop from the AC adapter, I will get ACPI errors like these: May 07 21:45:04 veritas root[7067]: ACPI group/action undefined: processor / LNXCPU:00 May 07 21:45:04 veritas root[7076]:...
11
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0answers
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Graph is too large for cairo-renderer bitmaps Error

Im trying to use pyreverse to generate images of UML diagrams for a project source code. When I run the pyreverse command and specify to generate .png images, it runs and then after a while, it shows: ...
9
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1answer
616 views

Why can't I “swapoff” when there's plenty of memory?

I've recently noticed that even though there's a lot of memory on my system: # free -m total used free shared buffers cached Mem: 15965 9680 ...
9
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0answers
862 views

What does hierarchy support do in cgroup?

cgroup has 2 options for memory control: memory.use_hierarchy = 1 : use hierarchy memory.use_hierarchy = 0 : use flat hierarchy, according to this answer What is the difference between the two? I ...
9
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1answer
1k views

How can I configure Yast to switch languages completely?

I have an installation of openSUSE 11.4 which was installed in German. I started Yast2 (which displayed in German, like "Netzwerkdienste") and switched the language to English under "System" -> "...
9
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2answers
2k views

Benefiting of sched_autogroup_enabled on the desktop

I am running a 2.6.37 kernel with sched_autogroup_enabled set to 1. I am not certain that I am seeing the benefits of this patch since: I am launching my applications from the desktop; applications ...
8
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3answers
1k views

Automatically switch display on lenovo docking and linux

I have a lenovo thinkpad with nvidia optimus and a mini docking station series 3. I want that while docked, it should automatically switch to an external monitor if possible and if I undock it, it ...
8
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2answers
2k views

Using and understanding systemd scheduling-related options in a desktop context

In systemd service files, one can set the following scheduling related options (from the systemd.exec man page, correct me if I'm wrong): Nice Sets the default nice level (scheduling ...
7
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1answer
237 views

How is it possible to be able to browse the web, when I can't resolve domains?

My networking is clearly bollixed, but I can't figure out how: derek@vinka:~$ nslookup google.com ;; connection timed out; no servers could be reached derek@vinka:~$ curl google.com <HTML><...
7
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2answers
2k views

Microphone volume on USB soundcard very low, snd_usb_audio options?

I have a C-Media USB soundcard installed on my Raspberry Pi: Bus 001 Device 004: ID 0d8c:0008 C-Media Electronics, Inc.. It is a USB cable with an XLR end on the other side, to which I have an XLR ...
7
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1answer
14k views

Why does startx give a black screen, with no errors?

I recently wanted to solve a problem with using a second monitor from my laptop that is running debian (jessie) but because I lack knowledge things didn't go as planned. Now I am getting booted into ...
7
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2answers
3k views

volume hot keys in Crunchbang don't work

I've spent 2 hours on this and still can't figure this out. It's driving me insane. Please save my sanity. When I press mute, the pnmixer control in the top right shows that I've pressed mute, but ...
7
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2answers
1k views

How to set up an encrypted directory to be mounted only during samba access?

(This is not about restricting client access, for which ext3 permissions do the trick) I'd like to encrypt the data on my NAS drive (Buffalo LinkStation Pro with SSH access enabled, if that matters) ...
6
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1answer
207 views

What is the purpose of extrausers?

Can someone explain the purpose, and benefits, of having an additional and separate extrausers user database in certain Linux systems (such as in Debian or in Ubuntu Core)? Why is not the standard /...
6
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1answer
3k views

USB ports keep resetting on Linux

Problem USB Ports (2.0) keep resetting causing connected peripherals to stop working after some time. Hardware Motherboard: ASUS J1800I-C CPU: Intel(R) Celeron(R) CPU J1800 @ 2.41GHz RAM: 4GB ...
6
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2answers
290 views

Is sending the SIGKILL to a swapped process unswapping it before killing?

Suppose that I want to terminate a process on Linux machine with swap (which is actually a zram). The swap is a half of RAM's size. There is only 10% of free space in RAM and the swap is almost full ...
6
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1answer
1k views

Linux Mint - Not detecting monitor connected via USB-C to HDMI hub

I recently bought a laptop (Asus Zenbook Flip) and installed Linux Mint. Now I want to connect two external monitors. Connecting the first through the HDMI port works without problems, but for the ...
6
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1answer
573 views

OOM from iterating over very large memory map

I'm writing a simulator that relies on generating a (potentially) very large problem domain. As the data can't fit in RAM, I use 4 four memory mapped files to hold it. This is a 64-bit application ...
6
votes
1answer
188 views

group member unable to write to a group-writable file with reiserfs and extended ACLs

Users vi and rust share group rust and want to use some file in shared manner. rust$ ls -l myfile -rw-rw-r-- 1 vi rust 0 May 30 03:48 myfile rust$ stat myfile | grep Gid Access: (0664/-rw-rw-r--) ...
6
votes
1answer
546 views

Simulate ethernet cable unplugged on a remote machine while staying connected

I am working from home on remote embedded Linux machine "X" via ssh. It has one physical network card. I need to simulate Ethernet cable unplugged condition on the same remote machine "X" , while ...
6
votes
1answer
543 views

Check if a remote machine is in a Veritas cluster

How can I verify that a remote machine is part of a Veritas cluster? I just created the following ssh command to verify if the remote machine is a VRTS cluster or a Linux availability Red Hat cluster ...
6
votes
1answer
210 views

Get quota usage information as non-privileged user

I have non-privileged access to a Linux server (shared PHP+MySQL hosting) and there are disk space, memory, CPU usage, I/O quotas. I wonder how can I get information about max/current quota usage ...
6
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1answer
5k views

Intel Skylake + DisplayPort 1.2 MST/Daisy chain on Linux

I am planning to buy hardware for using DisplayPort 1.2's MST feature to daisy chain two monitors in combination with the Intel Core i5 6600 Skylake processor on Ubuntu. Is this supported yet with the ...
6
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0answers
895 views

How to read the output of the show-memory-usage SysRq?

I couldn’t find any (recent) documentation on reading the output of the show-memory-usage SysRq (Alt+SysRq+m). So what can one learn from looking at it? Here is an example output form my box (Kernel ...
6
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0answers
4k views

Does the timeslice depend on process priority or not under Completely Fair Scheduling?

I'm trying to understand the Completely Fair Scheduler (CFS). According to Robert Love in Linux Kernel Development, 3rd edition(italics his, bold mine): Rather than assign each process a timeslice,...
6
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1answer
5k views

GNU/Linux: “device mapper: create ioctl failed” “device or resource busy”

I can't mount my encrypted devices anymore. The error is: device mapper: create ioctl failed device or resource busy This error arises both with two different programs to access TrueCrypt ...
6
votes
1answer
299 views

Can I limit total cputime used by a cgroup?

Although cgroups seemingly allow to control the CFS bandwidth of a cgroup, I don't see a way of enforcing a cpu time limit on a cgroup. The use case is that I would like to catch student programs that ...
6
votes
1answer
2k views

What is ionice `none: prio 0` equivalent to?

The ionice manual states that: Note that before kernel 2.6.26 a process that has not asked for an io priority formally uses "none" as scheduling class, but the io scheduler will treat such ...
6
votes
1answer
540 views

Is it possible to send data to the the shell of another pseudo-terminal?

This image shows how pseudo-terminals work: If I have two terminal emulators open, I can send the string "Hello" from the first terminal emulator to the second terminal emulator: echo "Hello" > /...
6
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1answer
726 views

LVM cache and TRIM

I have set up LVM to cache a logical volume (located on an HDD) on a partition of an SSD (in writeback mode if this matters). As far as I can tell, this works correctly and the cache uses all ...
6
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3answers
7k views

USB Media filesystem problem

My USB is not detected recently, I tried mount, fdisk, dd, gparted, mkfs.vfat :~# tail -f /var/log/syslog Oct 27 12:54:29 mohammad-Inspiron-N5110 kernel: [18843.105772] usb 3-2: New USB device ...
5
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0answers
99 views

How to compare string values with seccomp?

Some Linux system calls (such as execve, openat) have string type arguments. But the comparison function SCMP_CMP provided by seccomp seems to be comparing two pointers. So how can I limit files that ...
5
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0answers
1k views

Cannot connect to WiFi with nmcli, although secrets are provided

I am using nmcli on ArchLinux (version 1.14.5dev+17+gba83251bb-1 from the official package repository) to connect to wifi. This works perfectly for all wireless networks apart from this one Vodafone ...
5
votes
1answer
118 views

Due to a broken monitor, I need move my screen to the left

A fraction of the right side of my laptop screen is broken, in order to use only the good part the resolution needs to be about 1280x1024, aligned to the left. A simple xrandr -s 1274x1080 will get ...
5
votes
1answer
188 views

How was Unix installed in the 70's-80's?

Well I've been around computers since the late 80's(I was like 3 actually). Went the whole mile: Atari Xl-XE, MS-DOS, Windows 3.1, 95, etc. Then started using Linux because of the looks(yes I know, ...
5
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1answer
664 views

unshare --map-root-user switch to original uid/username after setup

I'm using unshare to create per process mounts, which is working perfectly fine by unshare -m --map-root-user However, after having created my bind-mounts by mount --bind src dst I want to change ...
5
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1answer
1k views

Cannot see packets arrive on application socket that were seen by Wireshark

Using Ubuntu 14 I have a Linux machine where there are two interfaces: eth1: 172.16.20.1 ppp0: 192.168.0.2 ppp0 is connected to a device which has a PPP interface (192.168.0.1) and a WAN interface (...
5
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0answers
515 views

Change Search Highlight Color In Less

I am a bit lost here on customizing the search/find highlight color or font format if you will. I understand that using LESS_TERMCAP_* we can alter the font format of less display. Full capabilities ...
5
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0answers
3k views

S.gpg-agent.browser not found while adding ppa in debian

I am using debian strech. I try to add repostory for vim with python support , while adding I encountered gpg-agent.browser not found error sudo add-apt-repository ppa:pi-rho/dev [sudo] password ...
5
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0answers
338 views

Limiting per process dirty bytes without slowing down the whole system

Given a busy system with a really fast block device (highend NVMe raid, 2 GB/s write, 4 GB/s read) mounted at /data and an a really slow device (USB HDD with spinning 8 TB disk, 50 MB/s write, 60 MB/s ...
5
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0answers
3k views

Linux 3.x fails assigning PCI BAR memory

I got an IBM x3850 type 8864 machine, I can successfully boot using a 2.6.32 kernel but when I try to use a 3.10 kernel or newer the kernel fails to initialize all PCI slots (I can fix this (manually),...
5
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1answer
977 views

Can I use a read-write root filesystem disk image as an OverlayFS upperdir?

Is it possible to union-mount an existing disk image containing a root filesystem to the upperdir of an overlayfs mount for read-write access? I'm trying to union-mount some old disk images to a /tmp/...
5
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0answers
4k views

Can't install Manjaro

I want to install a 'nix operating system alongside my Windows OS but nothing seems to work. I have a 128GB SSD I use for Windows, and I'm trying to split my 1TB HDD between Kali Linux and Manjaro (I ...
5
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0answers
6k views

How to change password of LDAP user?

Is it possible to change password for logged in LDAP user using passwd command? I have logged in to server1 using testuser. Trying to change password for itself (testuser) and got the below error. ...
5
votes
0answers
3k views

“-bash: /root/.bashrc: Permission denied” when logging in

I have this server running Centos 7. Every time I log in (remotely or locally) with every user I get an error. If I log in as root I get -bash: /root/.bashrc: Permission denied If I log in as a ...
5
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0answers
189 views

“leaky bucket” style disk io throttling using linux kernel

My goal is to prevent one kvm guest's disk i/o usage from negatively affecting other kvm guests on the same host. The host has one disk array - and separating guests onto different physical disks is ...
5
votes
1answer
2k views

Wrong inode: corrupted f2fs, fsck.f2fs cannot repair

A f2fs partition on my Android phone has recently become corrupted. It will still mount fine; however, I completely lost access to one directory (/data/media/0), which now shows as empty. Yet the disk ...
5
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0answers
614 views

Setting umask of libvirt/virt-manager for proper permissions in a directory shared by host and guest

I'm attempting to create a directory that is fully available to both the host and guest systems of a virt-manager/libvirt/QEMU/KVM virtual machine, with read, write and execute permissions for non-...
5
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0answers
4k views

Linux strace not following child processes even with -f (multithreaded parent)

Note: there are several similar questions, with the general answer being "If you want to trace a multithreaded process, or follow children, use -f". This doesn't help me, as i am using -f already. I ...