Linux is the generic term for a UNIX-like open source operating system based on the Linux kernel.

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4
votes
1answer
5k views

MySQL high CPU usage on small website

I have a small website hosted on a dedicated server (FreeBSD 9.2, MySQL 5.6.1 and php 5.5.5). The problem is that MySQL eats a lot of cpu resources even if the website have a few visitors. The ...
1
vote
0answers
34 views

Use of CPUQuota in systemd

I am trying to put a hard limit in CPU usage for a dd command . I have created the following unit file [Unit] Description=Virtual Distributed Ethernet [Service] ExecStart=/usr/bin/ddcommand ...
0
votes
2answers
38 views

How to find faulty memory module from MCE message?

I am trying to understand MCE message to find which memory module is bad on a server. This message appears in /var/log/kern.log in one server that freezes two times today. Apr 13 22:39:22 mbox ...
-2
votes
0answers
23 views

how to bridge two network interfaces to access guest ubuntu server [closed]

I am running ubuntu as guest inside virtualbox on osx host. There are 2 network cards configured: That allows me to work localy through a fixed IP and in the same time access internet on the ...
1
vote
3answers
97 views

Very irregular disk write performance and repeated SATA timeouts

I have a new 8TB Seagate Archive disk in one of my machines (Ubuntu 14.04.2, Kernel 3.19 from git.freedesktop.org, MSI 7817, Haswell chipset, i5-4570 CPU) and there are multiple issues with this disk. ...
65
votes
5answers
123k views

What version of RHEL am I using?

From the shell and without root privileges, how can I determine what Red Hat Enterprise Linux version I'm running? Ideally, I'd like to get both the major and minor release version, for example RHEL ...
-2
votes
1answer
25 views

Postfix Email Server Manipulation

I have one postfix mail server (postfix-2.10.1-6.el7.x86_64) under CentOS7. Now, our App Department is using it to send sms'es via email. To: 123456789@domain.tld To: 987654321@domain.tld To: ...
1
vote
1answer
1k views

Problems installing php5 from source in Ubuntu

(Originally asked here: http://stackoverflow.com/questions/14977119/problems-installing-php5-from-source-in-ubuntu) I've been trying to install php5 for a while. I'm using. Ubuntu 12.10 Apache ...
0
votes
0answers
4 views

No audio from the standard Jack ports [migrated]

I've recently had network issues with desktop PC so I had to open it up to do some troubleshooting (then I found out that the WiFi card was dead). Since I put everything back together, I haven't been ...
0
votes
1answer
919 views

lmtp: connect(backend) failed: Connection refused

A long time ago I'm trying to fix this error but I'm still locked, I appreciate any help :). I detail all that I have and what I am trying to do. I am using Cyrus Murder and apparently everything ...
1
vote
1answer
876 views

NFSv3 + ACL: mask is gone on clients

I'm sharing a NFS folder among a user group. The default umask on the clients is 0700, and this is a problem because newly created files won't be readable/writable by another users. So, I'm using ...
0
votes
0answers
19 views

getting /dev/kmsg into mongodb via rsyslog [closed]

Given the following config module(load="imkmsg") module(load="imtcp") module(load="mmjsonparse") module(load="ommongodb") input(type="imtcp" port="13514" Ruleset="mongodb") ...
0
votes
0answers
9 views

centos 7 installation with customized bridge module [migrated]

I have installed latest Centos 7 x64 edition in my server. I need to modify the linux-bridge module with some customized changes and use it as a default bridge module. Currently I am building centos ...
5
votes
1answer
343 views

Can I allow root to su any other user? [closed]

I have this centos VPS with 5 accounts; then I enabled one user to ssh, disabled root login, and have shell disabled for every other user account.. Is to possible to permit root to su the other ones ...
1
vote
2answers
905 views

Create a general character devices pair

I'd like to create a character device which has the same properties as a standard pseudo-terminal, but that can be named in a specific name. Basically I'd like to have /dev/pts/my-unique-name instead ...
0
votes
1answer
1k views

cannot create a folder under /mnt with root access rhel5.4

I'm not able to create a folder under /mnt error: mkdir: Cannot create directory 'test': No such file or directory I'm logged in as root: as file permissions : drwxr-xr-x 2 root root 0 mnt
4
votes
2answers
4k views

Issues with VSFTPD / FTP on Linux Ubuntu server - Steps for Troubleshooting?

I am dealing with an issue I am unclear on how to resolve and have been pulling my hair out for some time. I have been trying to configure an FTP user using the following (we use this same ...
1
vote
0answers
47 views

Is rbash secure if user login and ssh passwords are disabled?

I've got a server that I want to use as an SSH gateway for remote and local port forwarding. I don't want arbitrary commands to be able to be executed on it, only my scripts. I keep reading about how ...
62
votes
3answers
53k views

how to disable SSH login with password for some users?

On Linux (Debian Squeeze) I would like to disable SSH login using password to some users (selected group or all users except root). But I do not want to disable login using certificate for them. ...
4
votes
4answers
725 views

What do I need to send an Extended DHCPOFFER with multiple boot options?

According to Wikipedia and a bazillion other pages, you can have: Proxy DHCP If a PXE redirection service (Proxy DHCP) receives an extended DHCPDISCOVER, it replies with an extended DHCPOFFER ...
-1
votes
1answer
28 views

Why must the IP be configured on the bridge device? [closed]

My understanding of a network bridge is having a kind of "virtual switch" which virtually connects the network devices (that were added to the bridge) as if I would connect them to a real switch with ...
-2
votes
0answers
28 views

EC2 - Lamp Memory Usage Issue [closed]

I have the latest Amazon Linux AMI running on a medium instance with 4gb of Ram. LAMP server is setup with a single Wordpress instance. I am having memory issues that I can't seem to pinpoint my ...
-5
votes
0answers
22 views

LINUX ADD USER Command shell [closed]

Someone know how i can add a user with a directory and password already set, a single command?
-1
votes
1answer
23 views

creating snapshot for mongodb

I am trying to create snapshot for mongodb on centos 6.6. root@ ~]# lvscan File descriptor 12 (pipe:[23409]) leaked on lvscan invocation. Parent PID 3579: /bin/bash File descriptor 13 ...
-1
votes
0answers
20 views

linux boot from usb instead of hard disk instead [closed]

I want to install centos on 1 partition without modifying the current bootloader which boots up a hackintosh or windows. How do I install centos so that when I have to boot into it I select usb from ...
-3
votes
0answers
33 views

/sbin/lsmod outputs empty module list [closed]

I'm using the command /sbin/lsmod to check loaded kernel modules and drivers as described on centos.org The command output the following only: Module Size Used by No modules are ...
4
votes
3answers
3k views

How to increase swap space on a live server [duplicate]

On Ubuntu 14.04, the swap file has to be increased as the memory and swap usage are reaching 100% usage. On a live production server, can the swap be increased with minimal disruption to the service? ...
8
votes
3answers
16k views

How to increase swap size?

Recently, I put more ram into my server and now I have got a total of 24GB of RAM. Originally, I setup the OS to have a 2GB swap size. /dev/sdc1 1 281 2257101 82 Linux ...
5
votes
5answers
26k views

How to mount an ISO file in Linux?

I have just created ISO using these instructions: http://serverfault.com/questions/5689 How can I mount this iso image that was created?
1
vote
1answer
1k views

Starting nginx with systemctl fails, but running the command manually doesn't

On Arch Linux, for some reason, when I try to start nginx with the command "systemctl start nginx", it fails, with this being the output of "systemctl status nginx": Loaded: loaded ...
1
vote
0answers
15 views

how to overcome conflict between 2 network cards - virtualbox ubuntu [migrated]

I am running ubuntu 10.4.04 LTS as guest in virtualbox on OSX Yosemite. Unfortunatelly I seem to have the network configured wrong I followed this tutorials ...
3
votes
2answers
2k views

information about /proc/pid/sched

Not sure this is the right place for this question, but here goes: I'm trying to make some sense of the /proc/pid/sched and /proc/pid/task/tid/sched files for a highly threaded server process, ...
8
votes
1answer
481 views

Poor iSCSI performance with SSD disks and 10 Gbe network

iSCSI Target Ubuntu 14.04 (Trusty Tahr) with 16 GB RAM and 16 core CPU as LVM backed iSCSI target using three Samsung SSD disks, each capable of doing 65k IOPS using an LSI 6 Gbit/s ...
-4
votes
0answers
25 views

How much servers do I need? [closed]

in my homework for the university i have to create a data for a bank. For this i have several software programs like the core banking system, some risk management programs, SAP ERP, ibm lotus notes ...
0
votes
1answer
868 views

Apache 2.2, worker mpm, mod_fcgid and PHP: Can't apply process slot

We're having an issue on an apache server where every 15 to 20 minutes it stops serving PHP requests entirely. On occasions it will return a 503 error, other times it will recover enough to serve the ...
45
votes
16answers
10k views

Favorite rsync tips and tricks

The more I use rsync the more I realise that it's a swiss army knife of file transfer. There are so many options. I recently found out that you can go --remove-source-files and it'll delete a file ...
1
vote
2answers
9k views

Check the Number of active connections on port 80?

I have a webserver, i need to check number of connections in my server at that given time, i used following netstat -anp |grep 80 |wc -l this returned with 2542 but from my google ...
27
votes
8answers
63k views

How to display certain lines from a text file in Linux?

I guess everyone knows the useful Linux cmd line utilities head and tail. Head allows you to print the first X lines of a file, tail does the same but prints the end of the file. What is a good ...
0
votes
1answer
417 views

rsync --files-from specifies folders but does not copy files, recursive does not fix it

I've just recently revisited a script that I maintained a few years back and trying to get it to work on a new server. It basically runs the following rsync -vaP --copy-unsafe-links ...
1
vote
1answer
34 views

How can I allow users to reset their Linux user passwords from a web interface? [closed]

I am running SAS Visual Analytics on a cluster for my department. I want the users to be able to set and reset their own password for their user account. Users and Passwords for the application are ...
1
vote
0answers
8 views

Allowing users to mount arbitrary directories

I'm attempting to roll out eCryptFS support for users on our RHEL infrastructure. One large snag has come up. Given a user with no root access and (preferably) without the use of sudo, how would one ...
2
votes
2answers
959 views

csync2 Config command failed error

I've installed csync2 on two nodes with the following config: nossl * *; group cluster { host node1; host (node2); # Slave host key /etc/csync2/csync2.key; include /home; ...
4
votes
1answer
2k views

How to reliably map vSphere disks <-> Linux devices

Task at hand After a virtual disk has been added to a Linux VM on vSphere 5, we need to identify the disks in order to automate the LVM storage provision. The virtual disks may reside on different ...
2
votes
4answers
385 views

Use logger in shell script

How can I use logger in a shell script? If I run ntpd -qnp pool.ntp.org 2> >(logger) in console, it works as expected. If I put it into a shell script #!/bin/sh ntpd -qnp pool.ntp.org ...
0
votes
0answers
39 views

is there a way to determine what process has written a file? linux [duplicate]

The answer marked as duplicate is not related to my question which is very specific. I need to know if there is a command or information stored on linux about how a particular file was written please. ...
19
votes
5answers
1k views

Extremely fast booting server

I'm changing the way that our DHCP/DNS stuff works at work. Currently we've got 3 DNS servers, and a DHCP box. All of them are VMs. There's a circular dependency where stuff booting requires NFS, ...
3
votes
2answers
854 views

Winbind/AD: Local users with identical AD usernames

We are getting ready to add Winbind/Samba to some CentOS servers. Identity Management for UNIX is running on our DC, and it's testing well so far. There is one scenario I'm having trouble with, and ...
2
votes
1answer
34 views

How to get the DHCP-controlled DNS domain name for my Ubuntu machines in a Windows network?

I've been going in circles for a while trying to figure this out. I have a number of Ubuntu machines (some virtual) on a Windows network. From a Windows machine, I can ping or nslookup the Ubuntu ...
-3
votes
0answers
17 views

How to disable Symbolic link creation option to users in cPanel server? [closed]

In shared hosting server, one user is trying to upload 100s of symbolic link files and trying to access files out side. Mostly it is for malicious purpose. In this image, you can see 100s of symlink ...
11
votes
4answers
3k views

How do I prevent GNU Screen from reseting my prompt? [closed]

When I run screen it changes my prompt. How do I prevent this behaviour? For example: $ echo $PS1 \[\e]0;\h:Prod\a\]\n\[\e[32m\]\u@\h \[\e[33m\]\w\[\e[0m\]\n\$ $ screen $ echo $PS1 [\u@\h \W]\$ ...