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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70
votes
12answers
10k views

What is the benefit of compiling your own linux kernel?

What benefit could I see by compiling a Linux kernel myself? Is there some efficiency you could create by customizing it to your hardware?
58
votes
8answers
122k views

How can I monitor disk io?

I'd like to do some general disk io monitoring on a debian linux server. What are the tools I should know about that monitor disk io so I can see if a disk's performance is maxed out or spikes at ...
16
votes
3answers
15k 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 ...
51
votes
3answers
54k views

Why do I need a tty to run sudo if I can sudo without a password?

I have configured sudo to run without a password, but when I try to ssh 'sudo Foo", I still get sudo: sorry, you must have a tty to run sudo. Why does this happen and how can I work around it?
33
votes
2answers
28k views

Difference between pts and tty

Possible Duplicate: What is the exact difference between a 'terminal', a 'shell', a 'tty' and a 'console'? I always see pts and tty when I use the who ...
25
votes
2answers
60k views

What user should apache and PHP be running as? What permissions should /var/www files have?

I just spun up an Ubuntu 11.10 box and then ran apt-get install apache2 php5 to install apache2 and PHP 5 on the box. Now it is functioning as a "web server" and it loads the "It Works!" page. Now I'm ...
31
votes
12answers
47k views

Efficiently delete large directory containing thousands of files

We have an issue with a folder becoming unwieldy with hundreds of thousands of tiny files. There are so many files that performing rm -rf returns an error and instead what we need to do is something ...
34
votes
9answers
42k views

Linux distribution geared towards developers [closed]

I am looking for the best flavor of Linux that would appeal to the developer's side of me. I am a lover of open source and use several different languages. Is there such a thing as a Linux geared ...
32
votes
4answers
31k views

Creating a ram disk on Linux

I have a machine with 62GB of RAM, and a trunk that's only 7GB, so I thought I would create a RAM disk and compile there. I am not a Linux expert. I found instructions on the internet to create the ...
22
votes
3answers
14k views

How to Determine the Amount of RAM Slots In Use?

I forgot how many RAM modules are installed on my laptop. I do not want to unscrew it but want to look it up on the console. How do I gather this information?
32
votes
9answers
14k views

Why put things other than /home to a separate partition?

So recently a Debian 5.0.5 installer offered me to have separate /usr, /home, /var and /tmp partitions (on one physical disk). What is the practical reason for this? I understand that /home can be ...
20
votes
3answers
959 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: ...
13
votes
4answers
17k views

How to inject keystrokes via a shell script?

I'm trying to inject keystrokes into the input daemon so as to simulate typing from a Bash script. Is this possible, and if so, how can I make it happen?
12
votes
1answer
5k views

What does the Virtual kernel Memory Layout in dmesg imply?

While going through the "Output of dmesg" I could see a list of values which i am not able to understand properly. Memory: 2047804k/2086248k available (3179k kernel code, 37232k reserved, 1935k ...
11
votes
1answer
45k views

How to set the resolution in text consoles (troubleshoot when any `vga=…` fails)

It is a common way to set the resolution of a text consoles (that are usually available by Ctrl-Alt-F1 thru Ctrl-Alt-F6) by using a vga=... kernel parameter. I'm using Ubuntu 10.04 Lucid, output of ...
6
votes
6answers
11k views

How does a kernel mount the root partition?

My question is with regards to booting a Linux system from a separate /boot partition. If most configuration files are located on a separate / partition, how does the kernel correctly mount it at boot ...
32
votes
1answer
971 views

What happens when Ctrl + Alt + F<Num> is pressed?

I am looking for an explanation of what happens in Linux when this key combination is pressed to change the current terminal. In particular, what software component intercepts this key combination and ...
29
votes
2answers
4k views

Will Linux start killing my processes without asking me if memory gets short?

I was running a shell script with commands to run several memory-intensive programs (2-5 GB) back-to-back. When I went back to check on the progress of my script I was surprised to discover that some ...
26
votes
12answers
2k views

How can I tweak my Linux desktop to be more responsive?

I have the experience that Linux works fine until the physical memory is exhausted. As soon as swap space is used the performance is severely degraded and the GUI becomes unresponsive. This problem ...
13
votes
1answer
13k views

How to convert a shell script into a binary executable?

I want to convert my shell scripts into binary executable so that nobody else could edit or read it. Is there a way to convert it into a binary executable?
9
votes
4answers
26k views

How can I change the default “ens33” network device to old “eth0” on Fedora 19?

I've just installed a Fedora 19 on VMware workstation 9. The default network device is "ens33" instead of "eth0" on RHEL. The reason I have to use "eth0" is that the license component of one of our ...
13
votes
6answers
1k views

Ideal Hardware for GNU/Linux Laptop

What's the best way to find a laptop with hardware that is amenable to installing and running GNU/Linux? I'm looking for something that will ideally work with GPL'd drivers and/or firmware. I took a ...
24
votes
3answers
10k views

A list of available DBus services

Is there such a thing as list of available DBus services? I've stumbled upon a few (like those provided by NetworkManager, Rhythmbox, Skype, HAL). I wonder if I can find a rather complete list of ...
22
votes
2answers
29k views

Manually generate password for /etc/shadow

I need to manually edit /etc/shadow to change the root password inside of a virtual machine image. Is there a command-line tool that takes a password and generates an /etc/shadow compatiable password ...
17
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 ...
11
votes
4answers
8k views

'mv' equivalent of drag and drop with replace?

In a GUI environment, a drag-and-drop with replace will replace files and entire directories (including contents) with whatever is being copied in. Is there a way to accomplish this same intuitive ...
9
votes
3answers
39k views

How to rename multiple files in single command or script in Unix? [duplicate]

I have the below list of files aro_tty-mIF-45875564pmo_opt aro_tty-mIF-45875664pmo_opt aro_tty-mIF-45875964pmo_opt aro_tty-mIF-45875514pmo_opt aro_tty-mIF-45875524pmo_opt that I need to rename to ...
9
votes
5answers
5k views

Shell Script mktemp, what's the best method to create temporary named pipe?

I'm aware its best to create temporary files with mktemp, but what about named pipes? I have an idea, I'm sure it would work, but I would really like an expert opinion. I prefer things to be as ...
8
votes
3answers
11k views

The rc0.d,rc1.d,… directories in /etc

I'm running Ubuntu 10.04 LTS where I have the directories /etc/rc0.d, /etc/rc1.d, /etc/rc2.d, ..., /etc/rc6.d. Example files from my machine: directory example symlinks in the dir ...
5
votes
1answer
426 views

Give a specific user permissions to a device without giving access to other users

I have a card reader attached on /dev/sdb. What I do is giving all permissions to owner, group and the rest of the world, using: sudo chmod 777 /dev/sdb Can I just use another combination, ...
29
votes
3answers
11k views

Shell: how to go to the beginning of line when you are inside a screen?

I am inside a screen (screen -Ra). I have a long command, and I am at the end. Instead of keeping the left arrow, how can you go to the beginning of the line? CTRL-A works when I am in a normal ...
25
votes
5answers
23k views

How can I tell what version of linux I'm using?

Often times I will ssh into a new client's box to make changes to their website configuration without knowing much about the server configuration. I have seen a few ways to get information about the ...
19
votes
4answers
22k views

What is a spinlock in Linux?

I would like to know about spinlocks in detail? Could someone explain that to me?
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.
15
votes
2answers
52k views

Remove GPT - Default back to MBR

I keep receiving this error: Warning!! Unsupported GPT (GUID Partition Table) detected. Use GNU Parted I want to go back to the normal MBR. I found some advice here and did: parted /dev/sda ...
14
votes
2answers
8k 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 ...
12
votes
7answers
7k 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 ...
12
votes
2answers
7k views

Linux: Writing a watchdog to monitor multiple processes

A few years ago, a coworker came up with an elegant solution for a watchdog program. The program ran on Windows and used Windows Event objects to monitor the process handles (PID’s) of several ...
11
votes
2answers
10k views

How to re-mount a USB stick after unmounting from Nautilus without disconnecting it?

I find that in order to re-mount a USB stick, I have to physically disconnect it, and then re-connect it. How can I do this without such tiring physical action?
10
votes
2answers
72k views

Boot windows from grub rescue command prompt

Previously I had installed the Ubuntu 10.04 and Windows 7. Now I logged on to Windows, opened thepartition editor and deleted the volume containing the Ubuntu (Thought it will delete the Ubuntu and ...
8
votes
3answers
3k views

How can I monitor disk I/O in a particular directory?

I've got a few processes with a known name that all write to files in a single directory. I'd like to log the number of disk block reads and writes over a period (not just file access) to test whether ...
28
votes
4answers
1k views

Execution of possibly harmful program on Linux

I'm writing a program that will test programs written by students. I'm afraid that I can't trust them and I need to make sure that it won't end up badly for the computer running it. I was thinking ...
19
votes
2answers
72k 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?
17
votes
1answer
6k 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 ...
13
votes
3answers
2k 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
1answer
5k views

Ghost Vulnerability - CVE-2015-0235

Does the Ghost Vulnerability require access (as in being a logged in user) to the effected OS in question? Can someone clarify the 'remote attacker that is able to make an application call'? I only ...
12
votes
4answers
16k views

How to shutdown Linux at a specific datetime from terminal?

It seems I can shutdown using sudo shutdown by specifying a time or minutes. Is there a way to specify datetime for shutdown?
9
votes
2answers
3k views

Several questions about file-system character encoding on linux

Due to a lot of file exchange works between Windows (GBK encoding) and Linux (UTF-8 encoding), it will encounter character encoding issues easily, such as: zip/tar files whose name contains chinese ...
8
votes
2answers
5k views

Installing a package locally to a user - best practices?

I want to install Git locally to a user on a RHEL server (I don't have root access) What would be your cleanest/ most organized way of installing software to a local user account? Installing ...
4
votes
2answers
1k views

Swap alt and super

I have a Macbook Air that runs Linux. I want to swap the alt and super keys in both sides of the keyboard with each other. How do I do this with cli tools? Update Following Drav Sloan's answer I ...