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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.

10
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0answers
4k views

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
votes
0answers
391 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
229 views

How to know what is cached by dm-cache?

I am using dm-cache successfully for quite a while now. Now I would like to know which files are being currently in the cache. I understand that dm-cache works with blocks, not files, but since there ...
9
votes
0answers
836 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 ...
7
votes
0answers
150 views

My basic assumption about system “iowait” does not hold

My basic assumption about system "iowait" broke down. Is this expected? If it is expected, is there a set of conditions where I should expect my assumption to hold true? My basic assumption is that ...
6
votes
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,...
5
votes
0answers
80 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
votes
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
303 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
votes
0answers
2k views

Raise 128KiB limit on environment variables in Linux

Linux seems to have a default limit of 128KiB (131072) on the length of any single environment variable -- any attempt to set an envvar longer than this and then run any program will result in an '...
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
votes
0answers
3k 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
votes
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
votes
0answers
181 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
0answers
577 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
votes
0answers
3k 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 ...
5
votes
0answers
163 views

Why does /proc/*/status not account for all swap used on a system?

I have a system that has been swapping recently and am unable to account for all swap that is shown as in use by tools like free or top. Specifically, I can account for 19GB of 28GB swap used (...
5
votes
0answers
820 views

Linux does not proxy-arp for me, despite the documentation suggesting that it does

I am working on a PDP-10 emulator (see https://github.com/Rhialto/klh10 ). The operating system installed inside it may want to communicate with the outside world via IPv4 (which was just gaining use ...
5
votes
0answers
262 views

Restoring in-memory/swapped page state on resume from hibernation

I'm a big fan of Linux's hibernation support, which works extremely well on all the (admittedly slightly older) hardware I've tried it on. I highly prefer it to full shutdown and power up. There's ...
5
votes
0answers
2k views

systemd how to run service after docker.service

I have a service file, which executes a shell script, and the script needs to be executed after docker is started. Here is what I tried, but the script is started without waiting for the docker....
5
votes
0answers
4k views

Failed unmounting /home during shutdown arch linux

I've installed arch on my system multiple times and everything has worked fine, but since last installation I've been seeing messages : Failed unmounting /home. and Failed unmounting /run/user/1000. ...
5
votes
0answers
856 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 ...
5
votes
0answers
2k views

is THP good or bad for MySQL Server?

Linux kernel new feature called Transparent Huge Pages (THP) which is by default enabled on CentOS 6.x and above OS. Is THP good for MySQL DB machine? I am trying following to disabled THP but seems ...
5
votes
0answers
2k views

Routing traffic for specific user to specific interface

I have a Linux box with these interfaces: eth0 Link encap:Ethernet HWaddr 14:da:e9:ef:75:7d inet addr:176.9.85.182 Bcast:176.9.85.191 Mask:255.255.255.224 tun0 Link encap:UNSPEC ...
5
votes
0answers
1k views

Why are block sizes limited by page size in Linux?

In many (all?) file systems that Linux uses, including ext2/3/4, the maximum block size is the page size of the architecture Linux is running on, ie. 4KiB on x86. Why is there this limit? Might this ...
5
votes
0answers
538 views

Takeover delay in Heartbeat HA cluster

I have set up a heartbeat HA two node cluster. And both of server have same configuration of ha.cf #cat /etc/ha.cf logfile /var/log/ha-log autojoin none bcast eth1 warntime 20ms deadtime 40ms ...
5
votes
0answers
520 views

Is there a way to show all flags in /proc/mounts?

Some filesystem flags seem to be hidden in /proc/mounts, depending on whether they are defined as defaults. Is there a way to show all flags in /proc/mounts, also including the default ones? And if ...
5
votes
0answers
6k views

How to turn my linux laptop into wireless repeater?

I need to use my laptop to extend the range of my wireless router. I have a Samsung laptop with FEdora19 installed (but those should be irrelevant for a good answer). My wireless card supports master ...
5
votes
0answers
3k views

How do I find out the device node corresponding to my device in SuSE 8?

I'm forced to work with a bunch of point-of-sale systems running SuSE 8. They are my client's computers. We are stuck dealing with these old systems until they get to upgrade their whole fleet to SLE ...
5
votes
0answers
503 views

Setting Framebuffer splash resolution when exiting X

I installed a copy of BackTrack 5 R2 (Ubuntu 10.04) to my HDD and dual-booted with Windows 7. After a bit of tweaking I set about updating the native Intel drivers because it was only allowing me to ...
5
votes
0answers
568 views

Pulseaudio/X permission other user/SSH

My user user1 is running a graphical X session with pulse configured per-user. I need to run a graphical program that uses audio with user2. If I do su user2; program program doesn't start and I get ...
5
votes
0answers
580 views

Increasing serial baud rate within Ubuntu under VirtualBox

I'm debugging a kernel module under VirtualBox with a guest and host OS as Ubuntu 10.10. I'm using the virtualbox serial port but I'm maxing out at the baudrate 115200. My grub config looks like this.....
5
votes
0answers
2k views

Keyboard repeat without pressing a key

Occasionally a key repeats although I do not press the key. I would like to prevent this phenomenon. The phenomenon happens when I am pressing Ctrl+w again and again. After several times of Ctrl+w, w ...
4
votes
0answers
47 views

Is there any way to stop Mutter from removing decorations/borders of maximized windows?

I would like to be able to resize maximized windows on Mutter. Is there any way to tell Mutter to not remove the borders when the state is "maximized", so that I can maximize and then resize? Or, if ...
4
votes
0answers
38 views

H265 Supported Hardware

How do I know if underlying hardware supports H.264 or H.265 ? I want to play H.264/H.265 video by hardware encoding only. I am using Ubuntu-19.04 now.
4
votes
0answers
58 views

Problem with mouse area not reaching lower section

Under Debian 9.3 and 9.8 with OPENBOX and LIGHTDM. I have a problem with the mouse pointer on screen. Depending on the orientation, there is a section on screen that the mouse pointer doesn’t go. BUT, ...
4
votes
0answers
60 views

Laptop doesn't wake up after suspension

Whenever I enter suspension mode in my laptop, I cannot leave it: I can hear that a fan of the laptop is working, the power indicator shows that the laptop is on, and I can't return to Linux after ...
4
votes
0answers
816 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 ...
4
votes
0answers
265 views

Which filesystem will give me the best performance for both writing and reading small files?

My company developed an application that picks up (watches for) xml files of <10kb in size from a directory, reads it in sends the body as an api call to an external service and then moves the ...
4
votes
0answers
521 views

Passing environment variables around in systemd

EnvironmentFile is not an option as per this answer. I am trying to understand the recommended way of using and passing environment variables. I have a urxvtd.socket: [Unit] Description=urxvt ...
4
votes
0answers
83 views

find and symbolic link

I was skimming over the documentation of find to better utilize the command usage. I was reading the part that says GNU find will handle symbolic links in one of two ways; firstly, it can ...
4
votes
0answers
960 views

Accessing regular linux commands in Huawei's Dopra Linux

Backstory: I have a Huawei HG8245 router in my house and I want to change the default username/password. I've tried following this guide but the config file always gets reset. My ISP isn't helping ...
4
votes
0answers
70 views

Is there a reason why the value of a wchar_t retrieved by mbtowc() is not the UNICODE value?

If I convert the character 'ö' from a UTF-8 locale (where is is represented by the two octetts 0xC3 0xB6) to a wchar_t, I get a wchar_t value that is 0xF6. This applies to Linux and Solaris. If I ...
4
votes
0answers
331 views

How can I put a PCIe device into the D3 cold power state?

How do I transition an arbitrary PCIe device from the D0 state (powered on) to the D3 cold state (no current to the device) using common utilities on a Linux system? Presumably this involves writing ...
4
votes
0answers
71 views

no such file or directory trying to list or remove file in btrfs

I have a file system mounted btrfs. I have one directory in particular, that I can't remove, because it's listed as non-empty. In that directory, there's one file, which I can see the name of, but ...
4
votes
0answers
353 views

How to resize2fs ext4 partition that I shrunk with parted without e2fsck -f complaining of superblock or partition table

Please note that if I resize my partition back to original size with parted, I can then mount my /dev/vda1 partition without problems. But how can I get it to mount it after I SHRUNK it to 8GB? (...
4
votes
0answers
383 views

Running docker in docker in AWS Fargate

I am thinking of running docker in docker using this. Can I run it in AWS Fargate task? It doesn't have underlying host so was not sure that would work or not.
4
votes
0answers
44 views

Linux security policy plugins

The man page for sudoers(5) on Linux, says: NAME sudoers — default sudo security policy plugin What other "security plugins" are available for Linux systems?
4
votes
0answers
4k views

How to install weak cipher to connect to legacy SSH servers?

While we are upgrading our clusters, we noticed there are some legacy nodes that use very old version of openssh. Our current SSH clients cannot talk to them. How do we temporary install weak cipher ...