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

learn more… | top users | synonyms

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
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
4answers
941 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
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
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 ...
16
votes
4answers
473 views

Making Linux read swap back into memory

The Linux kernel swaps out most pages from memory when I run an application that uses most of the 16GB of physical memory. After the application finishes every action (typing commands, switching ...
16
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 ...
16
votes
2answers
5k 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
2answers
51k views

How do I make `ls` show file sizes in megabytes?

What commands do I need for Linux's ls to show the file size in MB?
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
11k 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
652 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
7answers
64k views

How to remove all the files in a directory?

I am trying to remove all files and subdirectories in a directory. I used rm -r to remove all files, but I want to remove all files and subdirectories, excluding the top directory itself. For ...
15
votes
4answers
6k 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
12k 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
10k 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
4answers
15k 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 ...
15
votes
11answers
60k 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
3answers
6k views

Understanding /dev and its subdirs and files

$ ls -l /dev/stdin /dev/fd/0 lrwx------ 1 tim tim 64 2011-08-07 09:53 /dev/fd/0 -> /dev/pts/2 lrwxrwxrwx 1 root root 15 2011-08-06 08:14 /dev/stdin -> /proc/self/fd/0 $ ls -l /dev/pts/2 ...
15
votes
5answers
10k 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 ...
15
votes
3answers
13k views

What is stored in /dev/pts files and can we open them?

According to my knowledge, /dev/pts files are created for ssh or telnet sessions.
15
votes
2answers
40k 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 ...
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
14k 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
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 ...
15
votes
1answer
26k 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 ...
15
votes
3answers
26k 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: ...
15
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 ...
15
votes
3answers
10k views

How to read environment variables of a process

Linux's /proc/<pid>/environ does not update (as I understand it, the file contain the initial environment of the process). How can I read a process's current environment?
15
votes
3answers
5k 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 ...
15
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 ...
15
votes
2answers
354 views

Open man page and search for string in a single command

Instead of doing man chmod and then /a+x to jump to the first section in the chmod man page that mentions a+x, I would like to know if there is a way to open the man page to a specific search string, ...
15
votes
6answers
301 views

What do I need to be aware of if I want to write an application that will run on any Linux distro?

I'm planning on writing an app that I would like to be able to run on any Linux installation without having to rewrite any of the code in doing so (except maybe the interface, GNOME vs KDE, etc). I'm ...
15
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 ...
15
votes
3answers
2k views

How to use three monitors on a laptop?

I have a laptop running Ubuntu 9.04 with a dual-head setup: laptop panel + external monitor. I'd like to add another monitor but the laptop has a single VGA port, so my question is: what are my ...
15
votes
5answers
27k views

Why is USB not working in Linux when it works in UEFI/BIOS?

For background I have just built a new machine with modern hardware including: AMD FX-8350 Gigabyte GA-990FXA-UD3 motherboard 16GB RAM NVidia GTX 650 Ti Kingston SSD Given that, I tried to install ...
15
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: ...
15
votes
2answers
632 views

Can I list the filesystems a running kernel can support?

I'm trying to detect what filesystems a kernel can support. Ideally in a little list of their names but I'll take anything you've got. Note that I don't mean the current filesystems in use, just ones ...
15
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 ...
15
votes
3answers
8k 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 ...
15
votes
2answers
2k views

Linux: Total swap used = swap used by processes +?

So, I'm trying to do some investigation on where does swap use come from in a system with high swap usage: # free total used free shared buffers cached Mem: ...
15
votes
3answers
383 views

How to force Linux kernel to “freeze” (or nearly freeze) for a few hundred milliseconds

We are running a real-time process on a non real-time kernel (CentOS 6), and this is probably not going to change. We have a streaming video application that requires about 500 MB/s of PCIe traffic ...
14
votes
2answers
2k views

Accidently created a file called -X, how can I delete it? [duplicate]

Possible Duplicate: How do I delete a file whose name begins with “-” (hyphen a.k.a. dash or minus)? Like an idiot, I ran this command: tar -cf -X awstats-icon icon ...
14
votes
6answers
69k views

Why does find -mtime +1 only return files older than 2 days?

I'm struggling to wrap my mind around why the find interprets file modification times the way it does. Specifically, I don't understand why the -mtime +1 doesn't show files less than 48 hours old. ...
14
votes
10answers
2k views

What linux is best suited for people new to computers?

What would be the easiest linux for people who are new to computers? The computers here have 256Mb RAM with 40GB hard-disks. UPDATE: Most of them apparently have more than 265MB of RAM with some ...