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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13
votes
1answer
228 views

Why is /dev full?

The /dev.. is full: SERVER:/dev # df -mP /dev Filesystem 1048576-blocks Used Available Capacity Mounted on udev 12042 12042 0 100% /dev There is no ...
13
votes
2answers
705 views

Why does Linux purge the memory cache when it is nearly full?

Here's what the memory graph looks like on a VPS running CentOS with 512MB of RAM and nginx/php-fpm/mysqld serving (mostly static) content to a couple thousand visitors per day. (those are days on ...
13
votes
5answers
246 views

Good website to link to for generic linux advocacy [closed]

I would like to have a link on website, both advertising the fact that I use (GNU/)linux, and pointing the curious reader to a source to learn more information. But I'm having trouble finding the ...
12
votes
3answers
2k views

Why there are many BSD systems but only one Linux kernel?

Why there are many BSD systems but only one Linux kernel? I wonder why BSD was forked many times, but no such thing with Linux.
12
votes
5answers
6k 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 ...
12
votes
3answers
554 views

Why do we need the reboot function in different binaries?

Why do we need the reboot function in different binaries? shutdown -r and reboot Or do they differ in something?
12
votes
4answers
10k views

What's the best way to join files again after splitting them?

If I have a large file and need to split it into 100 megabyte chunks I will do split -b 100m myImage.iso That usually give me something like xaa xab xac xad And to get them back together I have ...
12
votes
4answers
1k views

Skills required for a good Linux job

I am working as an IT Engineer in a reputed company in India. The problem is that though I was told that I would be given work on Linux, I am made to do work on Java and Windows. I am uncomfortable ...
12
votes
2answers
4k 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 ...
12
votes
2answers
410 views

What happens if I use vi on large files?

Though we were instructed not to, a colleague of mine used vi to view a large text file (server.log 3.5 GB). This filled up /var/tmp and caused some problems on the server. What caused this? Why ...
12
votes
3answers
797 views

Wait command usage in Linux?

#!/bin/bash function back() { sleep $1 exit $2 } back $1 $2 & b=$! if `wait $!`;then echo success else echo failure fi bash-3.00# ./back 300 0 failure bash-3.00# ./back 300 1 ...
12
votes
3answers
9k views

Linux, disable /dev/fd0 (floppy)

Is it possible to make Linux kernel completely ignore the floppy disk controller? I do not have the drive but obviously my motherboard does contain the controller. I would like to disable the /dev/fd0 ...
12
votes
5answers
6k 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 ...
12
votes
5answers
2k views

Is btrfs stable enough for home usage? [closed]

btrfs has finally found its way into the latest kernels, is it considered stable and safe enough to use in a home backup scenario (as an alternative to zfs) ?
12
votes
1answer
810 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 ...
12
votes
1answer
609 views

Why does the file command say that ELF binaries are for Linux 2.6.9?

Whenever I run file on an ELF binary I get this output: [jonescb@localhost ~]$ file a.out a.out: ELF 32-bit LSB executable, Intel 80386, version 1 (SYSV), for GNU/Linux 2.6.9, dynamically linked ...
12
votes
2answers
22k 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 ...
12
votes
4answers
2k views

Rock-stable filesystem for large files (backups) for linux

What filesystem would be best for backups? I'm interested primary in stability (especially uncorruptability of files during hard reboots etc.) but how efficiently it handles large (>5GB) files is also ...
12
votes
3answers
3k views

How to detect memory type under Linux?

Which Linux utility can tell me if I have registered or unbuffered ECC memory in my server? Lshw and dmidecode do not work for me; dmidecode provides no information about registered vs. unbuffered: ...
12
votes
2answers
2k views

How to blacklist a correct bad RAM sector according to MemTest86+ error indication?

MemTest86+ (the version included with Ubuntu 13.04) says Failing address: 002f796c48 - 759.5 MB What should I specify in the memmap kernel parameter to bypass this area? I've tried running ...
12
votes
2answers
737 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 ...
12
votes
4answers
2k views

Wipe last 1MB of a Hard drive

Is there an easy command that I can use to zero out the last 1MB of a hard drive? For the start of the drive I would dd if=/dev/zero of=/dev/sdx bs=1M count=1. The seek option for dd looks ...
12
votes
3answers
1k views

Can I limit a user (and their apps) to one network interface?

As the title really. I've actually got two scenarios to apply this: Multiseat Desktop: two network connections both with internet gateways and two accounts doing bandwidth-intensive tasks on each. I ...
12
votes
3answers
1k views

How can I have 400% CPU occupied on 2 cores

I understand that Σ(%CPU) ≤ logicalcores*(1+ε) (where ε is measure and rounding error). But, how can I have on a 2 core system 2 different processes, each taking 200% of CPU (as measured by htop)? ...
12
votes
3answers
6k views

How can I move the home directory to a separate partition?

I would like to install another distribution but keep my home directory. Is there a way to move the home directory to a separate partition? I don't have an external hard drive available to back up my ...
12
votes
2answers
241 views

`test` and `[` - different binaries, any difference?

I noticed while answering another question that test and [ are different binaries, but the [ manpage pulls up test's. Besides the requirement for an ending ], is there any difference? If not, why are ...
12
votes
6answers
6k views

Correlating /var/log/* timestamps

/var/log/messages, /var/log/syslog, and some other log files use a timestamp which contains an absolute time, like Jan 13 14:13:10. /var/log/Xorg.0.log and /var/log/dmesg, as well as the output of $ ...
12
votes
3answers
1k views

Given a git patch id, how to find out which kernel release contains it?

Assume I have some issue that was fixed by a recent patch to the official Linux git repository. I have a work around, but I’d like to undo it when a release happens that contains my the fix. I know ...
12
votes
2answers
2k views

What are the main differences between BSD- and linux-based operating systems?

I am a long time linux user and have recently become interested in playing about with BSD-based operating systems. What are the differences between linux and BSD-based systems. I am interested in ...
12
votes
1answer
367 views

Command to run a child process “offline” (no external network) on Linux

I have a program I would like to test in offline mode without taking down my actual network. This program would still need to connect to local sockets, including unix domain sockets and loopback. It ...
12
votes
2answers
329 views

How updated and relevant is “The Linux Documentation Project”?

I have been advised by many senior Unix/Linux Administrators to go through "The Linux Documentation Project" on the site www.tldp.org. Its undoubtedly a very rich site, but I saw many tutorials (as ...
12
votes
1answer
718 views

What are the benefits of the new teaming driver?

When compiling a 3.3 kernel, I noticed that a new driver called teaming was added to the networking system. According to the relevant commit teaming is a userspace-driven alternative to bonding. Has ...
12
votes
1answer
10k views

How to use Linux kernel driver bind/unbind interface for USB-HID devices?

First background. I am developing a driver for Logitech game-panel devices. It's a keyboard with a screen on it. The driver is working nicely but by default the device is handled by HID. In order to ...
12
votes
4answers
2k views

Read the stack of another process?

I'm trying to read a child process's stack but with no luck. I know it is possible using ptrace, but ptrace's interface allows you to read only one word at a time, and I'm trying to scan a larger ...
12
votes
3answers
2k views

Increasing kernel memory size

I have an embedded board with 512MB of RAM running Linux 2.6.29 and UBoot bootloader. But the kernel is able to utilize only 128MB of RAM. I tried changing the value of XCODE_MEMSIZE, which I think ...
11
votes
5answers
4k views

What is the difference between ls and l?

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 ...
11
votes
4answers
1k views

How Does Linux deal with shell scripts?

For this question, let's consider a bash shell script, though this question must be applicable to all types of shell script. When someone executes a shell script, does Linux load all the script at ...
11
votes
7answers
4k views

What's the best way to format a HDD in Linux in order to leave no trace?

I'm running Debian and need a way to format the entire hdd in order to not leave any trace on it because I want to donate it to a friend. So what will be the best way in order to format it? If I ...
11
votes
9answers
4k 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?
11
votes
5answers
9k views

How can I limit the bandwidth used by a process?

I have a CentOS 5.7 server that will be backing up its files nightly. I am concerned that visitors to the various sites that the server hosts will experience degraded performance while the backup is ...
11
votes
4answers
19k views

linux: How can I view all UUIDs for all available disks on my system?

My /etc/fstab contains this: # / was on /dev/sda1 during installation UUID=77d8da74-a690-481a-86d5-9beab5a8e842 / ext4 errors=remount-ro 0 1 There are several other disks on ...
11
votes
3answers
12k views

Which users are allowed to log in via SSH by default?

When I set up my Debian 6, I was wondering, which users apart from root whose password I know can log into my system via SSH? When I install Apache 2 a user called www-data gets created. Does this ...
11
votes
6answers
7k views

Is there a way to stop having to write 'sudo' for every little thing in Linux?

I'm a newbie when it comes to Linux. I do most of my development in a Windows environment. That said, I'm going to be doing a fair amount of PHP work shortly, and I'm interested in learning RoR, so ...
11
votes
4answers
3k views

How to give HTTP traffic higher priority?

When I surf the web, I find that I have to pause my BitTorrent client, to help improve the painfully slow speed (I'm sadly on a 384kbps line). It's not too nice to have to do this manually every time. ...
11
votes
5answers
2k views

Is there a way for linux to pick up the phone?

I know that there is a way to make Linux dial out using a modem. Is there a way to program Linux (using a library/device) to pick up the modem (record phone calls) etc? see caller id?
11
votes
8answers
2k views

How can I build a custom distribution for running a simple web browser?

You'll have to forgive me, as I'm relatively new at doing something like this, but I need to do the following and I know that it has and can be done. Basically, a few friends and me are assembling ...
11
votes
2answers
2k 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 ...
11
votes
3answers
3k views

(How) can I create a tmpfs as a regular (non-root) user?

The distribution is an Ubuntu server running the 2.6.35-30 Linux kernel. I would like to have a directory that sits completely in memory. Is this possible without root privileges?
11
votes
2answers
522 views

Contents of /proc

Is there a site someplace that lists the contents of /proc and what each entry means?
11
votes
5answers
8k views

How to list all files in the size order

I would like to list all files in the order of big to small in size and the files could be present anywhere in a certain folder.