Linux is the family of Unix-like operating systems that use the Linux kernel.
20
votes
4answers
9k views
Moving linux install to a new computer
I know that it can, in some circumstances, be difficult to move a Windows installation from one computer to another (physically move the hard drive), but how does that work on linux? Aren't most of ...
51
votes
6answers
5k views
Is Linux a Unix?
So, there are lots of different versions of Unix out there: HP-UX, AIX, BSD, etc. Linux is considered a Unix clone rather than an implementation of Unix. Are all the "real" Unices actual descendants ...
18
votes
2answers
3k 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 ...
38
votes
3answers
16k views
How do I read from /proc/$pid/mem under Linux?
The Linux proc(5) man page tells me that /proc/$pid/mem “can be used to access the pages of a process's memory”. But a straightforward attempt to use it only gives me
$ cat /proc/$$/mem ...
14
votes
7answers
788 views
Good Introductory resources for linux
Are there any good tutorials or resources I can read so that I am not confused by basic things like 'how to search all files in a directory and below for a given string', or 'how to find out how much ...
225
votes
7answers
19k views
Understanding the Linux kernel source
I am trying to understand how a function, say mkdir, works by looking at the kernel source. This is an attempt to understand the kernel internals and navigate between various functions. I know mkdir ...
19
votes
2answers
841 views
Can a bash script be hooked to a file?
I want a script to sleep unless a certain file is modifed/deleted (or a file created in a certain directory, or ...). Can this be achieved in some elegant way? The simplest thing that comes to my mind ...
3
votes
3answers
4k 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 ...
27
votes
5answers
15k views
What is a Superblock, Inode, Dentry and a File?
From the article Anatomy of Linux File Systems by Tim Jones, I read that Linux views all the file systems from the perspective of a common set of objects and these objects are superblock, inode, ...
45
votes
3answers
10k views
Why do directories need the executable (X) permission to be opened?
In my CMS, I noticed that directories need the executable bit (+x) set for the user to open them. Why is the execute permission required to read a directory?
13
votes
5answers
955 views
Getting information on a machine's hardware in Linux
How can I check what hardware I have? (With BIOS version etc.)
38
votes
9answers
21k views
SSH easily copy file to local system
If I'm logged in to a system via SSH, is there a way to copy a file back to my local system without firing up another terminal or screen session and doing scp or something similar or without doing SSH ...
35
votes
10answers
7k views
Recommended reading to better understand Unix/Linux internals
I've worked on *nix environments for the last four years as a application developer (mostly in C).
Please suggest some books/blogs etc. for improving my *nix internals knowledge.
8
votes
1answer
539 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.
2
votes
2answers
683 views
Installation on debian 5 32-bit without being a root
I am new to Linux and I am trying to install Skype and Google Chrome on my desktop. It runs Debian 5 32-bit. I downloaded the packages from the web but I have no idea how to install them. I have ...
10
votes
8answers
1k 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 ...
6
votes
2answers
5k views
Output traffic on different interfaces based on destination port
My question is basically the same as Only allow certain outbound traffic on certain interfaces.
I have two interfaces eth1 (10.0.0.2) and wlan0 (192.168.0.2).
My default route is for eth1.
Let's say ...
6
votes
2answers
3k views
Bash Script on Startup? (Linux)
Is there any way to make/run a bash script on reboot
(like in Debian/Ubuntu for instance, since thats what my 2 boxes at home have)
Also, any recommended guides for doing cron jobs? I'm completely ...
5
votes
3answers
2k views
Moved bin and other folders! How to get them back?
I accidentally moved all folders from root to a subfolder. (/bin, /etc, /home, /lib, /usr... all moved) The only ones that were not moved, since they were in use, are /bak, /boot, /dev, /proc, /sys.
...
7
votes
1answer
424 views
Log every invocation of every SUID program?
I would like to have a log file that contains an entry for every time a user runs any suid program, containing the user name, the program and any command line arguments passed to it. Is there a ...
3
votes
3answers
1k views
How do I know that my CPU supports 64bit operating systems under Linux?
How can I find out that my CPU supports 64bit operating systems under Linux, e.g.: Ubuntu, Fedora?
8
votes
2answers
1k views
real memory usage
if I understand correctly, in the following output produced by free, 3535m is the actual free memory available to applications, only 413m is used, is this correct? need some clarification on the ...
57
votes
2answers
5k views
Why do we use su - and not just su?
I don't understand why su - is preferred over su to login as root.
20
votes
2answers
6k views
What do the flags in /proc/cpuinfo mean?
How can I tell whether my processor has a particular feature? (64-bit instruction set, hardware-assisted virtualization, cryptographic accelerators, etc.) I know that the file /proc/cpuinfo contains ...
48
votes
15answers
2k views
How do you choose a distribution?
I'm currently looking at putting a Linux (although BSD is still an option) distribution on my old laptop. However, I'm not sure how to wade through all of my options - rolling releases versus not, ...
16
votes
6answers
5k views
Correctly determining memory usage in Linux
I'm a bit confused on some of the results I am seeing from "ps" and "free".
On my server, this is the result of "free -m"
[root@server ~]# free -m
total used free shared ...
13
votes
3answers
1k 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?
11
votes
3answers
2k views
How to fix Ctrl + arrows in Vim?
I am using Putty -> Suse box -> vim 7.2 combo for editing and want to remap Ctrl + arrows combo to a particular task. But for some reason, Vim ignores the shortcut and goes into insert mode and ...
21
votes
4answers
1k views
unix, difference between path starting with '/' and '//'
In unix/linux, any number of consecutive forwardslashes in a path is generally equivalent to a single forwardslash. eg.
$ cd /home/shum
$ pwd
/home/shum
$ cd /home//shum
$ pwd
/home/shum
$ cd ...
15
votes
4answers
2k views
What happens to the output of a process that has been disowned and lost its terminal?
If I close the virtual terminal, where some process was started, does the output just go straight to /dev/null, or can it pollute memory somehow?
Can I anyhow grab the output to continue reading it at ...
5
votes
2answers
994 views
How to restrict internet access for a particular user on the lan using iptables in Linux
Let's say there are two users on the LAN, A and B. How do I restrict user A from internet access using iptables rules and saving the rules so that after reboot, they are still effective. And suppose I ...
4
votes
4answers
849 views
How to recover a file just deleted [duplicate]
I just deleted a file in Nautilus with Shift+Delete, which warned me that "If you delete an item, it will be permanently lost." I wonder if there is no way to recover the file?
My OS is Ubuntu 10.10. ...
8
votes
4answers
3k views
how to “unswap” my desktop
If my desktop run out of memory and swaps a lot then I free or kill the application wasting my RAM. But, after that, all my desktop/applications have been swapped and are horribly slow, do you know a ...
7
votes
1answer
2k 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 ...
5
votes
2answers
944 views
Why is there a discrepancy in disk usage reported by df and du?
I have a Linux(CentOS) server, the OS+packages used around 5GB. Then, I transferred 97GB data from a Windows server to two folders on this Linux server, after calculated the disk usage, I see the ...
2
votes
5answers
2k views
Kernel can't find /dev/sda file during boot
I configured a gentoo kernel (kernel-2.6.36-gentoo-r5), but when I boot it can't mount /dev/sda1:
ALERT! /dev/sda1 does not exist . Dropping to a shell .
I use the shell to go to the /dev ...
4
votes
4answers
740 views
Should I install 32 or 64 bit?
I'm going to be installing linux on my 64bit netbook.
Last time I checked I was advised that for personal computers (not servers) it is best to install the 32bit version. I believe the reasoning was ...
4
votes
3answers
2k views
Automount USB drives with no GUI requirement (halevt replacement)
For minimal installations of Debian, I have been using halevt to enable automounting of USB drives. Halevt is reliable and requires no configuration aside from installing the package. Now, halevt has ...
1
vote
2answers
209 views
Is there a log of past threads that are now closed?
Sometimes, I have a rogue Java process which takes up 100% of my CPU and makes it jump about 30C in temperature (usually resulting in a crash if not killed).
Problem is, I can never really identify ...
18
votes
7answers
9k views
Linux Kernel: Good beginners' tutorial
I'm interested in modifying the kernel internals, applying patches, handling device drivers and modules, for my own personal fun.
Is there a comprehensive resource for kernel hacking, intended for ...
20
votes
3answers
3k views
why not kill -9 a process?
I am always very hesitant to run kill -9.
But I see other admins do it almost routinely.
I figure there is probably a sensible middle ground.
So:
When should kill -9 be used?
What should be tried ...
13
votes
2answers
21k 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 ...
20
votes
7answers
2k views
How can I use DD to migrate data from an old drive to a new drive?
I am upgrading the internal SATA hard drive on my laptop from a 40G drive to a 160G drive. I have a Linux/Ubuntu desktop which has a SATA card. I would actually like to do the same thing for a couple ...
14
votes
8answers
3k views
How do I find how long ago a Linux system was installed?
How can I find the time since a Linux system was first installed, provided that nobody has tried to hide it?
30
votes
7answers
1k views
ZFS under linux, does it work?
Could I get ZFS to work properly in Linux?
Are there any caveats / limitations?
23
votes
7answers
45k views
How do I find out what hard disks are in the system?
I need to know what hard disks are available, including ones that aren't mounted and possibly aren't formatted. I can't find them in dmesg or /var/log/messages (too much to scroll through). I'm hoping ...
7
votes
5answers
5k 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
2answers
8k views
timestamp, modification time, and created time of a file
I just know that ls -t, -f give different sorting of files and subdirectories under a directory.
Now I wonder what are the differences between timestamp, modification time, and created time of a ...
10
votes
4answers
1k views
Please explain Linux boot sequence in detail
I am preparing a document in detail showing light on the boot sequence of Linux right from pressing of Power-on button the host to the login prompt appearance.
It would be great if we could combine ...
9
votes
2answers
16k 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 ...
