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.

learn more… | top users | synonyms

27
votes
2answers
22k 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 ...
26
votes
4answers
49k views

How to make log-rotate change take effect

I followed this link to change log-rotate configuration for RHEL 6 After I made the change to config file, what should I do to let this take effect?
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
6answers
22k 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 ...
26
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?
26
votes
2answers
14k 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 ...
26
votes
3answers
20k views

File system compatible with all OSes?

I use Linux and Mac OS X on a regular basis, and sometimes I have to use Windows. I need to use a flash drive on all three, and I need a filesystem that will work well on all of them. None of the ...
26
votes
2answers
67k 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 ...
26
votes
2answers
6k 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
2answers
116k 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?
26
votes
1answer
39k 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
1answer
4k 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
6answers
21k 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 ...
25
votes
2answers
2k 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
2answers
19k views

What is the proper sudoers syntax to add a user?

According to the comments in /etc/sudoers (Fedora 13): ## Syntax: ## ## user MACHINE=COMMANDS ## ## The COMMANDS section may have other options added to it. My two related questions: What ...
25
votes
3answers
11k 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 / ...
25
votes
4answers
79k 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 ...
25
votes
2answers
83k 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
2answers
70k views

ifconfig command not found

I've just installed CentOS7 as a virtual machine on my mac (osx10.9.3 + virtualbox) .Running ifconfig returns command not found. Also running sudo /sbin/ifconfig returns commmand not found. I am root. ...
25
votes
8answers
10k 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
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
2answers
45k 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 ...
25
votes
4answers
37k 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
1answer
36k 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
4answers
26k 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 ...
25
votes
1answer
27k 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 ...
25
votes
5answers
7k 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 ...
25
votes
2answers
20k 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 ...
25
votes
1answer
28k 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 ...
25
votes
1answer
75k 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 ...
24
votes
5answers
13k views

What is the difference between ls and l? [duplicate]

I accidentally typed l instead of ls today and found that the command still printed a list of the files in my current directory. Trying l --help brings up the help file for ls suggesting that l is ...
24
votes
5answers
5k views

Is CTRL+C incorrect to use to return to command line?

When I'm using tail -f and I want to return to the shell, I always use CTRL+C. Or when I am typing a command and feel like aborting it and starting over, I simply CTRL+C to get back to an empty ...
24
votes
4answers
139k 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
24
votes
7answers
4k views

How to achieve portability with sed -i (in-place editing)?

I'm writing shell scripts for my server, which is a shared hosting running FreeBSD. I also want to be able to test them locally, on my PC running Linux. Hence, I'm trying to write them in a portable ...
24
votes
2answers
15k views

/proc/PID/fd/X link number

In Linux, in /proc/PID/fd/X, the links for file descriptors that are pipes or sockets have a number, like: l-wx------ 1 user user 64 Mar 24 00:05 1 -> pipe:[6839] l-wx------ 1 user user 64 Mar 24 ...
24
votes
2answers
53k 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?
24
votes
11answers
23k 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 ...
24
votes
2answers
68k views

Convert Amazon .pem key to Putty .ppk key Linux

I have generated and downloaded a private .pem key from AWS. However, to use Putty in order to connect to the virtual machine, I must have that key in .ppk format. The process of conversion is ...
24
votes
2answers
9k views

When was a process started

To know when was a process started, my first guess was to check the time when /proc/<pid>/cmdline was written/modified the last time. ps also shows a START field. I thought both of these ...
24
votes
3answers
44k 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 ...
24
votes
2answers
48k 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, ...
24
votes
3answers
798 views

How did the Linux Kernel project track bugs in the Early Days?

We all know that Linus Torvalds created Git because of issues with Bitkeeper. What is not known (at least to me) is, how were issues/tickets/bugs tracked up until then? I tried but didn't get anything ...
24
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?
24
votes
1answer
6k views

Run a command for a specified time and then abort if time exceeds

I want know how I can run a command for a specified time say, one minute and if it doesn't complete execution then I should be able to stop it.
24
votes
6answers
7k views

What's the most “correct” mount point for a permanent NTFS partition?

I have an NTFS partition (containing a Windows installation from which I dual boot) that I would like to permanently mount from my Linux installation. Problem is, I can't figure out what the ...
23
votes
3answers
81k views

linux + add X days to date and get new virtual date

I have Linux ( RH 5.3) machine I need to add/calculate 10 days plus date so then I will get new date (expiration date)) for example # date Sun Sep 11 07:59:16 IST 2012 So I need to get ...
23
votes
3answers
2k views

How can I shutdown a RHEL server at 06:45 tomorrow morning?

I just received notification that our site has a power outage tomorrow morning. I am a Windows admin but I have to cover for our Linux admin who's not around until tomorrow evening. I need to ...
23
votes
6answers
24k views

Execute a specific command in a given directory without cd'ing to it?

Is there a way to execute a command in a different directory without having to cd to it? I know that I could simply cd in and cd out, but I'm just interested in the possibilities of forgoing the extra ...
23
votes
6answers
35k views

How to replace one char with another in all filenames of the current directories?

How do you rename all files/subdirs in the current folder? Lets say, I have many files and subdirs that are with spaces and I want to replace all the spaces with an underscore. File 1 File 2 File 3 ...