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.

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28
votes
4answers
20k views

Resume transfer of a single file by rsync

In Ubuntu, I want to copy a big file from my hard drive to a removable drive by rsync. For some other reason, the operation cannot complete in a single run. So I am trying to figure out how to use ...
28
votes
3answers
7k views

Why do some Linux distributions still have /dev/ttyS0, ttyS1, etc., even though newer computers don't have such a serial port?

Many new laptop and desktop computers do not have 9-pin/25-pin serial ports. Why do many Linux distributions still contain /dev/ttyS0, dev/ttyS1 device files? Since udev can create the device files ...
28
votes
3answers
52k views

How to use GoToMeeting in Linux

My employer wants me and the team of developers to communicate with them using gotomeeting.com service. Is it possible to use GoToMeeting in Debian? I know that officially GoToMeeting supports only ...
28
votes
1answer
19k views

How OOM killer decides which process to kill first?

This answer explains the actions taken by the kernel when an OOM situation is encountered based on the value of sysctl vm.overcommit_memory. When overcommit_memory is set to 0 or 1, overcommit is ...
28
votes
1answer
2k views

Why isn't a straightforward 1/5/15 minute moving average used in Linux load calculation?

Until recently i thought the load average (as shown for example in top) was a moving average on the n last values of the number of process in state "runnable" or "running". And n would have been ...
28
votes
2answers
24k views

how to check rx ring, max_backlog, and max_syn_backlog size

Quite often in the course of troubleshooting and tuning things I find myself thinking about the following Linux kernel settings: net.core.netdev_max_backlog net.ipv4.tcp_max_syn_backlog net.core....
27
votes
9answers
7k views

Uninstalling programs on Linux

I've been using Windows and Mac OS for the past 5 years and now I'm considering to use Linux on a daily basis. I've installed Ubuntu on a virtual machine and trying to understand how I can use Linux ...
27
votes
3answers
5k views

What is the difference between these commands for bringing down a Linux server?

Reading "What is the difference between Halt and Shutdown commands?" , I generally have an idea what does the command shutdown does, with or without -h/-r options. The "halt" command performs ...
27
votes
4answers
91k views

How can I find available network interfaces?

This is in regard to linux, but if anyone knows of a general *nix method that would be good. I booted a system yesterday with an ethernet cable plugged in. "NetworkManager" is not installed, so once ...
27
votes
6answers
5k views

Why isn't there a truly unified package manager for Linux?

Why isn't there a unified package manager that acts as an interface between the end-user and the underlying low-level package manager (apt, yast, pacman, etc.)? Is it hard to do and therefore not ...
27
votes
2answers
2k views

Why does a software package run just fine even when it is being upgraded?

Say I am running a software, and then I run package manager to upgrade the software, I notice that Linux does not bring down the running process for package upgrade - it is still running fine. How ...
27
votes
6answers
25k views

How do I correlate /dev/sd devices to the hardware they represent?

A drive is beginning to fail and I only know the device by its /dev/sdb device file designation. What are the ways that I can use to correlate that device file to an actual hardware device to know ...
27
votes
3answers
1k views

Official list of programs to be included in Linux?

Is there a standard that I can refer to for the list of programs (e.g. cat, ls) that must be included in Linux?
27
votes
2answers
49k views

How to use command line to change volume?

I am trying to control the volume using my programming script. How can I do the following in Fedora 15, Ubuntu linux? Mute/ Unmute Volume up and volume down Note: Please note that I use a web USB ...
27
votes
2answers
60k views

Difference between cp -r and cp -a

Looking for the difference between cp -r and cp -a? What does recursive mean in terms of copying files from a folder?
27
votes
4answers
93k views

Why the default eth0 interface is down by default on CentOS?

I am already a little bit familiar with Linux distros like Debian or Ubuntu (yeah, very similar) but I wanted to try Red Hat based - CentOS 6.2 . I have installed it on my Windows 7 host in virtualBox ...
27
votes
2answers
15k views

What mount points exist on a typical Linux system?

I have 2 questions. During Linux installation we specify memory space for 2 mount points - root and swap. Are there any other mount points created without the users notice? Is this statement ...
27
votes
2answers
55k views

Too many levels of symbolic links

I created this file structure: test/src test/firefox When I run this command: ln -s test/src test/firefox I would expect a symbolic link test/firefox/src to be created pointing to test/src, ...
27
votes
2answers
75k views

Mount cifs Network Drive: write permissions and chown

I have access to a cifs network drive. When I mount it under my OSX machine, I can read and write from and to it. When I mount the drive in ubuntu, using: sudo mount -t cifs -o username=${USER},...
27
votes
4answers
28k views

What is the equivalent of Active Directory on Linux

I have a couple of machines at home (plus a number of Linux boxes running in VMs) and I am planning to use one of them as a centralized file server. Since I am more a Linux user rather than a ...
27
votes
12answers
3k views

How can I tweak my Linux desktop to be more responsive?

I have the experience that Linux works fine until the physical memory is exhausted. As soon as swap space is used the performance is severely degraded and the GUI becomes unresponsive. This problem ...
27
votes
3answers
6k views

What does the vm.swappiness parameter really control?

Per the kernel documentation: This control is used to define how aggressive the kernel will swap memory pages. Higher values will increase aggressiveness, lower values decrease the amount of swap. ...
27
votes
1answer
44k views

Setting /proc/sys/vm/drop_caches to clear cache

As part of doing some cold cache timings, I'm trying to free the OS cache. The kernel documentation says: drop_caches Writing to this will cause the kernel to drop clean caches, dentries and inodes ...
27
votes
4answers
126k views

How to find the installation path for a software under linux?

Under linux, I launch a software by typing, e.g., fluidplot. How can I find the installation path for this software?
27
votes
2answers
22k views

Reply on same interface as incoming?

I have a system with two interfaces. Both interfaces are connected to the internet. One of them is set as the default route; a side effect of this is that if a packet comes in on the non-default-route ...
27
votes
1answer
43k views

How to skip “permission denied” errors when running find in Linux? [duplicate]

Possible Duplicate: How do I remove “permission denied” printout statements from the find program? When I run this command in Linux (SuSE): find / -name ant I get many error ...
26
votes
6answers
23k views

Can we get compiler information from an elf binary?

Is there some chance to know how a binary was built, under Linux? (and or other Unix) Compiler, version, time, flags etc... I looked at readelf and couldn't find much, but there might be other ways ...
26
votes
4answers
156k views

Linux: set date through command line

How to change the system date in Linux ? I want to change: Only Year Only Month Only Date Any combination of above three
26
votes
5answers
2k views

How does Linux differentiate between real and unexisting (eg: device) files?

This is a rather low-level question, and I understand that it might not be the best place to ask. But, it seemed more appropriate than any other SE site, so here goes. I know that on the Linux ...
26
votes
3answers
3k views

Way to instantly fill up/use up lots of disk space?

On a Linux VM I would like to TEST the NAGIOS monitoring more deeply than just switching off the VM or disconnecting the virtual NIC; I would like to test or "enforce a disk space alarm" through ...
26
votes
1answer
30k views

What is kernel ip forwarding?

I have seen on many blogs, using this command to enable IP forwarding while using many network security/sniffing tools on linux echo 1 > /proc/sys/net/ipv4/ip_forward Can anyone explain me in ...
26
votes
2answers
7k views

How do I make a file NOT modifiable?

While logged in, I can do the following: mkdir foo touch foo/bar chmod 400 foo/bar chmod 500 foo Then I can open vim (not as root), edit bar, force a write with w!, and the file is modified. How ...
26
votes
5answers
8k views

Corruption-proof SD card filesystem for embedded Linux?

Recently we had a rather unpleasant situation with our customer - Raspberry Pi based "kiosk" used to display remote sensing data (nothing more fancy than a kiosk mode browser displaying a self-...
26
votes
1answer
31k views

What is meant by mounting a device in Linux?

I've heard the term "mounting" when referring to devices in Linux. What is its actual meaning? How it handling now unlike older versions? I haven't done that manually via the command-line. Can you ...
26
votes
1answer
5k views

How to set per process swapiness for linux?

/proc/sys/vm/swappiness is nice, but I want a knob that is per process like /proc/$PID/oom_adj. So that I can make certain processes less likely than others to have any of their pages swapped out. ...
26
votes
1answer
8k views

Why doesn't Linux use the IANA Ephemeral port range?

According to Wikipedia The Internet Assigned Numbers Authority (IANA) suggests the range 49152 to 65535 for dynamic or private ports. Many Linux kernels use the port range 32768 to 61000. Even ...
25
votes
2answers
3k views

How frequently is the proc file system updated on Linux?

How frequently is the proc file system updated on Linux? Is it 20 milliseconds (time quantum)?
25
votes
3answers
12k views

When should I use a trailing slash on a directory? [duplicate]

Possible Duplicate: How linux handles multiple path separators (/home////username///file) Most commands I use in linux behave exactly the same whether I include the trailing slash / character ...
25
votes
3answers
66k views

How can I benchmark my HDD?

I've seen commands to benchmark one's HDD such as this using dd: $ time sh -c "dd if=/dev/zero of=ddfile bs=8k count=250000 && sync" Are there better methods to do so than this?
25
votes
3answers
93k views

How to rename multiple files in single command or script in Unix? [duplicate]

I have the below list of files aro_tty-mIF-45875564pmo_opt aro_tty-mIF-45875664pmo_opt aro_tty-mIF-45875964pmo_opt aro_tty-mIF-45875514pmo_opt aro_tty-mIF-45875524pmo_opt that I need to rename to ...
25
votes
2answers
91k views

How to display open file descriptors but not using lsof command

Hi I have read Here that lsof is not an accurate way of getting the number of File Descriptors that are currently open. He recommended to use this command instead cat /proc/sys/fs/file-nr While ...
25
votes
8answers
11k views

How does Linux kernel compare to microkernel architectures?

I read once that one advantage of a microkernel architecture is that you can stop/start essential services like networking and filesystems, without needing to restart the whole system. But considering ...
25
votes
11answers
24k views

Linux replacement for Apple Keynote software?

I am trying to migrate from Mac OS X to a Linux distribution, maybe/probably Ubuntu. One of my favorite applications for the Mac was Apple Keynote, which makes amazing sideshow presentations. Is ...
25
votes
3answers
2k views

Which are the standard commands available in every Linux based distribution?

I would like to know which are the standard commands available in every Linux system. For example if you get a debian/ubuntu/redhat/suse/arch/slackware etc, you will always find there commands like: ...
25
votes
3answers
49k views

show gateway IP address when performing ifconfig command

Currently, when using the ifconfig command, the following IP addresses are shown: own IP, broadcast and mask. Is there a way to show the related gateway IP address as well (on the same screen with ...
25
votes
4answers
39k views

How is an Interrupt handled in Linux?

I just know that Interrupt is a hardware signal assertion caused in a processor pin. But I would like to know how Linux OS handles it. What all are the things that happen when an interrupt occurs?
25
votes
5answers
52k views

How to know which Linux and which version I am using

When I run cat /proc/version command in terminal, I got below output: Linux version 2.6.18-348.1.1.0.1.el5 (mockbuild@ca-build56.us.oracle.com) (gcc version 4.1.2 20080704 (Red Hat 4.1.2-54)) #1 SMP ...
25
votes
1answer
37k views

How is a message queue implemented in the Linux kernel?

I would like to know how Message Queues are implemented in the Linux Kernel.
25
votes
3answers
3k views

How can I set the processor affinity of a process on Linux?

The question is all in the title: How can I set the processor affinity of a process on Linux?
25
votes
1answer
82k views

reading from serial from linux command line

I have a serial port device that I would like to test using linux command line. I am able to use stty and echo for sending commands to serial port, but when device responds I have no way of reading ...