Questions specifically about Linux, as opposed to Unix-like systems in general, or to questions about a specific distribution or program.

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17
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1answer
7k views

Linux: What is a tainted kernel?

Under certain conditions, the Linux kernel may become tainted. For example, loading a proprietary video driver into the kernel taints the kernel. This condition may be visible in system logs, kernel ...
17
votes
3answers
4k views

Linux: Kill process based on arguments

How can I kill a process based on its command line arguments? killall, pgrep, and pkill seem to only work based on the process name. I need this to be able to differentiate between a number of ...
17
votes
2answers
29k views

What is the difference between ioctl(), unlocked_ioctl() and compat_ioctl()?

Going through the linux 2.6.36 source code at lxr.linux.no, I could not find the ioctl() method in file_operations. Instead I found two new calls: unlocked_ioctl() and compat_ioctl(). What is the ...
17
votes
6answers
25k views

How to see disk details like manufacturer in Linux

With sfdisk -s I can see the disk capacity as follows: $ sfdisk -s /dev/cciss/c0d0: 143338560 total: 143338560 blocks How do I see disk details like disk manufacturer? I tried hdparm, but got an ...
17
votes
2answers
13k 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 ...
17
votes
1answer
12k 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 ...
17
votes
3answers
29k views

Can I connect to Windows machine from Linux shell?

I can connect to Linux machines from Windows using PuTTY/SSH. I want to do the other way round - connect to a Windows machine from Linux. Is this possible?
17
votes
1answer
3k views

per process swapiness for linux

/proc/sys/vm/swappiness is nice but i want a knob that's 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 unlike ...
17
votes
1answer
7k views

What is maximum RAM supportable by Linux?

What is the maximum supportable RAM by Linux? Assume that hardware is/supports 64-bit. Among all Linux distros. Does it go up to 16 exabytes, or is it limited like with Windows which I believe is 192 ...
17
votes
1answer
2k views

Who creates /etc/{group,gshadow,passwd,shadow}-?

In any linux system I have access to (a couple of Archlinuxes, an Ubuntu, a Debian Sid and a Gentoo) there are the following 4 files in /etc/, all ending with a dash: /etc/group- /etc/gshadow- ...
16
votes
3answers
873 views

How much does the Linux kernel change in one year?

How can I get statistics about how much (in percents) the Linux kernel source code changes in one year?
16
votes
4answers
16k views

sending text input to a detached screen

I'm trying to run a minecraft server on my unRAID server. The server will run in the shell, and then sit there waiting for input. To stop it, I need to type 'stop' and press enter, and then it'll ...
16
votes
5answers
2k views

How is the linux graphics stack organised?

Can anybody explain(hopefully with a picture), how is the linux graphics stack organised? I hear all the time about X/GTK/GNOME/KDE etc., but I really don't have any idea what they actually do and how ...
16
votes
2answers
44k 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 ...
16
votes
5answers
11k views

Using different versions of Python

Background: Since I develop python programs that must run on different python versions, I have installed different versions of python on my computer. I am using FC 13 so it came with python 2.6 ...
16
votes
5answers
31k views

How can I find the hardware model in Linux?

I used a system information utility to take the model number of a system, and also of the motherboard. DMI System Manufacturer LENOVO DMI System Product 2306CTO DMI System Version ...
16
votes
5answers
3k views

What constitudes a 'field' for the cut command?

For example, the cut command can take a parameter -f, which according to man select only these fields; also print any line that contains no delimiter character, unless the -s ...
16
votes
3answers
16k views

Linux network troubleshooting and debugging

From time to time Linux and Unix users faced with various network problems. Many of these problems are presented here and at some others troubleshooting forums, but the are very concrete and contains ...
16
votes
5answers
16k views

How to find which process is regularly writing to disk?

How can I find which process is constantly writing to disk? I like my workstation to be close to silent and I just build a new system (P8B75-M + Core i5 3450s -- the 's' because it has a lower max ...
16
votes
1answer
559 views

How is new hardware support added to the linux kernel?

Imagine there's a company A that releases a new graphics adapter. Who manages the process that results in this new graphics adapter being supported by the Linux kernel in the future? How does that ...
16
votes
5answers
3k 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 ...
16
votes
6answers
5k views

Can ps display only non kernel processes on Linux?

How can I ask ps to display only user processes and not kernel threads? See this question to see what I mean...
16
votes
1answer
2k views

What is Linux doing differently that allows me to remove/replace files where Windows would complain the file is currently in use?

The example I have is Minecraft. When running Bukkit on Linux I can remove or update the .jar files in the /plugins folder and simply run the 'reload' command. In Windows, I have to take the whole ...
16
votes
1answer
5k views

init process: ancestor of all processes?

I have always learned that the init process is the ancestor of all processes. Why does process 2 have a PPID of 0? $ ps -ef | head -n 3 UID PID PPID C STIME TTY TIME CMD root ...
16
votes
2answers
4k views

How does one change the delay that occurs after entering an incorrect password?

After entering an incorrect password at a login prompt, there s an approximately 3-second delay. How can I change that on a Linux system with PAM?
16
votes
3answers
32k 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 ...
16
votes
5answers
4k views

How to start a new Linux distro?

Some of my friends and I are interested in starting a new Linux distro. How do we do that? What do we need to plan? Backstory I represent a community of Linux sysadmins/implementors whose special ...
16
votes
4answers
946 views

Linux adoption path for a .NET developer [closed]

I am a .NET C# programmer, I love the .NET stack. I have tried Linux several times but every time I got put off as I could not do anything on it .. (like program for it or on it). Ever since Mono was ...
16
votes
3answers
5k views

Difference between UUID from blkid and mdadm?

Can someone explain the difference between the UUID's reported by blkid and mdadm? On one of our CentOS systems, for example: [root@server ~]# blkid | grep /dev/md1 /dev/md1: ...
16
votes
1answer
2k views

Shebang line with `#!/usr/bin/env command --argument` fails on Linux

I've got a simple script: #!/usr/bin/env ruby --verbose # script.rb puts "hi" On my OSX box, it runs fine: osx% ./script.rb hi However, on my linux box, it throws an error linux% ./script.rb ...
16
votes
2answers
6k views

Why does high disk I/O reduce system responsiveness/performance?

I never quite understood why high disk I/O slowed the system so much. It's strange to me because I would expect the slow-down to affect only those processes dependent on the hard/optical drive data, ...
16
votes
1answer
20k views

How can I set up logrotate to rotate logs hourly?

According the the Unix and Linux Administration Handbook and man, logrotate has options for daily, weekly, and monthly, but is there a way to add an hourly option? This blog post mentions you can set ...
15
votes
4answers
1k views

Why not always use rsync?

I wanted to ask is there any reason not to use rsync for everything and abandon cp? I wasn't aware of rsync and now I don't know why cp is ever needed.
15
votes
10answers
5k views

What is the smallest possible Linux implementation?

What are the bare minimum components for a Linux OS to be functional, and that I can use as a base to expand and improve as I learn Linux and my understanding and needs grow?
15
votes
5answers
24k views

Linux ls to show only filename date and size

How can I use ls in linux to get a listing of filenames date and size only. I don't need to see the other info such as owner or permission. Is this possible?
15
votes
3answers
2k views

How to know where a program is stuck in linux?

I am running the following command on my ubuntu server root@slot13:~# lxc-stop --name pavan --logfile=test1.txt --logpriority=trace It seems to hang indefinitely. Whenever this happened on AIX, I ...
15
votes
6answers
14k 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 ...
15
votes
5answers
12k 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 ...
15
votes
4answers
655 views

What is new in Kernel 3.0?

I understand this is somewhat less Ubuntu related, but it affects it. So,what is so new about it that Linus decided to name it 3.0? I'm not trying to get information about the drivers that got into ...
15
votes
4answers
7k views

Binary compatibility between Mac OS X and Linux

Brace yourselves, this question will likely appear naive and/or foolish, seeing as I am relatively new to the inner workings of unix like systems, and programming in general. Ready? Ok! I will go ...
15
votes
5answers
13k views

How can I see dmesg output as it changes?

I'm writing a device driver that prints error message into ring buffer dmesg output. I want to see the output of dmesg as it changes. How can I do this?
15
votes
3answers
11k views

How can I reserve a block of memory from the Linux kernel?

I have a device that needs a block of memory that is reserved solely for it, without the OS intervening. Is there any way to tell BIOS or the OS that a block of memory is reserved, and it must not ...
15
votes
6answers
2k 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 ...
15
votes
5answers
2k views

Is there any reason why I get ^[[A when I press up arrow at the console login screen?

Whenever I'm at the console login, I press up arrow intentionally to see the previously typed commands. But I see this ^[[A. But when I press Ctrl Alt Print Screen Scroll Lock Pause Break Page Up ...
15
votes
11answers
61k views

Cannot enable network after CentOS 6.3 fresh install

I am trying to perform a fresh CentOS 6.3 installation then run various yum commands such as yum install httpd. The installation runs fine, however I cannot run any network based commands like yum I ...
15
votes
2answers
1k views

Why writing to /dev/random does not make parallel reading from /dev/random faster?

Typically reading from /dev/random produces 100-500 bytes and blocks, waiting for an entropy to be collected. Why doesn't writing information to /dev/random by other processes speed up reading? ...
15
votes
2answers
6k views

Can I watch the progress of a `sync` operation?

I've copied a large file to a USB disk mounted on a Linux system with async. This returns to a command prompt relatively quickly, but when I type sync, of course, it all has to go to disk, and that ...
15
votes
3answers
3k views

Why don't you need to update drivers? (Or do you?)

In my life I've not once updated drivers on any of my Linux systems, though they have all been desktops. A friend was asking me why one does not need to update Linux drivers and I found myself unable ...
15
votes
3answers
15k views

Extracting SFX files in Linux

I am trying to extract an SFX file under Linux Mint 15 (64 bit) but it's not working. I've done chmod +x on the file and tried to run it like a script with no luck (it gives me an error that there's ...
15
votes
3answers
27k views

Yum: How can I view variables like $releasever, $basearch & $YUM0?

I am setting up a yum repository, and need to debug some of the URLs in the yum.conf file. I need to know why is Scientific Linux trying to grab this URL, when I was expecting it to grab another URL: ...