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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18
votes
4answers
22k 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?
18
votes
3answers
17k views

Where can I see a list of kernel killed processes?

Is there some way I can check which of my processes the kernel has killed? Sometimes I log onto my server and find that something that should've run all night just stopped 8 hours in and I'm unsure if ...
18
votes
7answers
6k views

Linux equivalent to ReadyBoost?

Is there a kernel module or some other patch or something similar to Windows' ReadyBoost? Basically I'm looking for something that allows disk reads to be cached on a Flash drive.
18
votes
1answer
12k views

What is difference between User space and Kernel space?

Is Kernel space used when Kernel is executing on the behalf of the user program i.e. System Call? Or is it the address space for all the Kernel threads (for example scheduler)? If it is the first ...
18
votes
3answers
19k views

What is the most high-performance Linux filesystem for storing a lot of small files (HDD, not SSD)?

I have a directory tree that contains many small files, and a small number of larger files. The average size of a file is about 1 kilobyte. There are 210158 files and directories in the tree (this ...
18
votes
3answers
5k views

Why does the 'bin' user need a login shell?

During an audit of /var/log/auth.log on one of my public webservers, I found this: Jan 10 03:38:11 Bucksnort sshd[3571]: pam_unix(sshd:auth): authentication failure; logname= uid=0 euid=0 ...
18
votes
2answers
5k 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 ...
18
votes
2answers
4k views

How does sudo remember you already entered root's password?

When using sudo on Linux, it asks for root password, but only the first time you run it. If you run another sudo command, it remember you already entered the password previously and doesn't ask for ...
18
votes
6answers
2k views

Is there a way to limit overall CPU consumption?

My laptop (an HP with an i3 chip) overheats like crazy every time I run a resource heavy process (like a large compilation, extracting large tarballs or ... playing Flash). I am currently looking ...
18
votes
2answers
65k 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?
18
votes
1answer
20k 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 ...
18
votes
2answers
39k views

How to recover a crashed Linux md RAID5 array?

Some time ago I had a RAID5 system at home. One of the 4 disks failed but after removing and putting it back it seemed to be OK so I started a resync. When it finished I realized, to my horror, that 3 ...
18
votes
2answers
15k 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 ...
18
votes
2answers
13k views

Booting native Arch Linux on an Android device

I have a Galaxy Note 10.1 (n8010) and I want to make it boot Arch Linux natively. I mean boot Arch Linux instead of android. All that I need is to alter the initramfs, which I can't find anywhere in ...
17
votes
4answers
19k views

How do I make multiple directories at once in a directory?

I know with mkdir I can do mkdir A B C D E F to create each directory. How do I create directories A-Z or 1-100 with out typing in each letter or number?
17
votes
5answers
3k views

Understanding UNIX permissions and their attributes

I've never really got how chmod worked up until today. I followed a tutorial that explained a big deal to me. For example, I've read that you've got three different permission groups: owner (u) ...
17
votes
7answers
19k views

Disable screen blanking on text console

I'm running linux clusters, mostly on SLES10. The servers are mostly blades, accessed via remote console. There is a real console in the server room, but switched off. I would like to disable the ...
17
votes
8answers
3k views

The most universal scripting language for Linux is?

We are writing scripts for Linux systems, there has been some debate over what would be the most universally Linux present scripting language to use. Bash, SH, Posix? What?
17
votes
4answers
2k 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 ...
17
votes
3answers
3k views

Standard and/or common directories on Unix/Linux OSes

Coming from the Windows world, I have found the majority of the folder directory names to be quite intuitive: \Program Files contains files used by programs (surprise!) \Program Files (x86) contains ...
17
votes
2answers
73k views

How can get a list of all scheduled cron jobs on my machine?

My sysadmin has set up a bunch of cron jobs on my machine. I'd like to know exactly what is scheduled for what time. How can I get that list?
17
votes
2answers
16k views

Get the chmod numerical value for a file

In FreeBSD and also in Linux, how can I get the numerical chmod value of a file? For example, 644 instead of -rw-r--r--? I need an automatic way for a Bash script.
17
votes
4answers
5k views

Why does dd from /dev/random give different file sizes?

I am running the following command on an ubuntu system: dd if=/dev/random of=rand bs=1K count=2 However, every time I run it, I end up with a file of a different size. Why is this? How can I ...
17
votes
3answers
6k 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 / ...
17
votes
2answers
8k 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 ...
17
votes
4answers
3k views

What happens if you edit a script during execution?

I have a general question, which might be a result of misunderstanding of how processes are handled in Linux. For my purposes I am going to define a 'script' as a snippet of bash code saved to a text ...
17
votes
2answers
2k views

Why is JFS so obscure?

When I first got into using Slackware years ago I quickly learned to love JFS over ext3 or reiserfs given that it was reliable and if there was an unclean shutdown, its disk checking was very very ...
17
votes
4answers
44k 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 ...
17
votes
3answers
1k views

How to automate Linux server configuration?

Is there any way to automate Linux server configuration? I'm working on setting up a couple of new build servers, as well as an FTP server, and would like to automate as much of the process as ...
17
votes
2answers
30k views

What does aux mean in `ps aux`?

ps aux seems to conveniently list all processes and their status and resource usage (Linux/BSD/MacOS), however I cannot comprehend the meaning of parameter aux using man ps. What does aux mean?
17
votes
4answers
6k views

Block Particular Command in Linux for Specific user

How to block command, let say mkdir for specific user ? What I did just created read-only function and store in users profile ~/.bashrc /bin/mkdir() { echo "mkdir command not allow for you" ...
17
votes
2answers
28k 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
3answers
5k views

Determining Specific File Responsible for High I/O

This is a simple problem but the first time I've ever had to actually fix it: finding which specific files/inodes are the targets of the most I/O. I'd like to be able to get a general system overview, ...
17
votes
3answers
26k 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
7answers
51k views

Unix/Linux undelete/recover deleted files

Is there a command to recover/undelete deleted files by rm? $ rm -rf /path/to/myfile How can I recover myfile? If there is such a tool how can I use it?
16
votes
6answers
3k views

Why do most linux distros default gnome? [closed]

Why the default desktop environment of most popular linux distros is gnome? KDE seems to me an equally good desktop environment. Is it for licence reason? historic? or else?
16
votes
8answers
17k views

How to determine which sd* is usb? [duplicate]

Possible Duplicate: How to know if /dev/sdX is a connected USB or HDD? The output of ls /dev/sd* on my system is - sda sda1 sda2 sda3 sda4 sda5 sda6 sda7 sdb sdc sdc1 sdc2 ...
16
votes
3answers
847 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
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
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
150k views

how to check OS and version using Linux commmand [duplicate]

what is the Linux command to check the server OS and its version? Connected the server using shell.
16
votes
5answers
14k 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
2answers
1k views

Why does `kill -l` not list signal numbers of 32 and 33?

Executing kill -l on linux gives: 1) SIGHUP 2) SIGINT 3) SIGQUIT 4) SIGILL 5) SIGTRAP 6) SIGABRT 7) SIGBUS 8) SIGFPE 9) SIGKILL 10) SIGUSR1 11) SIGSEGV ...
16
votes
1answer
554 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
6answers
23k 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 ...
16
votes
5answers
2k 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
4k 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
2answers
12k 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 ...
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
1answer
10k 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 ...