Linux refers to the family of Unix-like computer operating systems using the Linux kernel. If your question is about a certain distribution only, use a more specific tag.

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Does running commands verbosely make them slower?

I've found myself using the -v flag for lots of applications less and less (especially for trivial stuff like tar and cp). However, when I did and I was, say, unzipping a large file, it would take ...
28
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8answers
9k views

Booting Linux off USB pendrives

Booting a Linux system off USB Pendrives is one of my favorite things. On a laptop we have the following advantages, The Harddisk can be shutdown and that reduces power consumption (hdparm) The ...
28
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5answers
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How to use different network interfaces for different processes?

I have two network interfaces on a Linux PC, and I need to manually set the interface that a given process will use. The program (Twinkle softphone) does not have a similar option, so I believe that ...
28
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4answers
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How to update Google chrome in Ubuntu?

How to update Google chrome in Ubuntu?
28
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1answer
23k views

How do file permissions apply to symlinks?

Let's say you have this structure: + directory -- file1 -- file2 -- file3 -> /tmp/file3 file3 is a link to another file3 somewhere else on the system. Now let's say I chmod 777 the directory ...
28
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5answers
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How do I physically find a wifi device using a laptop or mobile phone

Okay, so I have lost my tablet somewhere in my flat and have been searching for hours already. It is an Android device, which seems to have wifi enabled (responds to pings), but doesn't seem to react ...
27
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4answers
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How to create a file which is named like a command line argument?

I was wondering how to make a file named as a flag, e.g., if I wanted to make a folder named -a, what commands would do the trick? I tried mkdir '-a', mkdir \-a, and neither worked. I'm on Ubuntu.
27
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9answers
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How to convert Word (doc) to PDF in linux?

I have a set of files in .doc format, that need to be converted to .pdf format. I am using Ubuntu linux.
27
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3answers
70k views

Get a list of Open Ports in Linux

I need a Linux command to list all free open ports for use in an application lsof -i TCP| fgrep LISTEN Does not seen to be helping as the Ports it lists are not necessarily free for use. How do I ...
27
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3answers
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How to get list of dependencies of non-installed RPM package?

apt-cache show <package> shows also it's dependencies. yum info <package> does not show dependencies, but it obviously know them. How to ask yum for dependencies of specified package?
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6answers
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Swap partition size for 4GB RAM

I'm planning to install Ubuntu 9.04 version. How much space should I dedicate for swap partition. I remember setting it to double the RAM size when I installed long back. At that time my RAM was 256 ...
27
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4answers
13k views

What is the different between 'locate' and 'find' in Linux?

Why there are two so similar command in Linux? and normally what are the circumstances to use each of them?
27
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2answers
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Why is “/dev/rdisk” about 20 times faster than “/dev/disk” in Mac OS X

According to the rasbery pi documentation, You can load your OS to a flash card with either /dev/disk or /dev/rdisk. rdisk stands for raw disk. /dev/disk is a block level device, why would rdisk ...
27
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3answers
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Does rm -f follow symbolic links?

I have a directory like this: $ ls -l total 899166 drwxr-xr-x 12 me scicomp 324 Jan 24 13:47 data -rw-r--r-- 1 me scicomp 84188 Jan 24 13:47 lod-thin-1.000000-0.010000-0.030000.rda ...
27
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7answers
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How to know which Linux Distribution I'm using?

How to know which Linux Distribution I'm using? uname -a gives Linux xxxxxx.net 2.6.9-42.0.3.EL.wh1smp #1 SMP Fri Aug 14 15:48:17 MDT 2009 i686 i686 i386 GNU/Linux How can I know this is ...
26
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2answers
4k views

Why is it so hard to find a file in Ubuntu?

It's very hard to find files in Ubuntu. In Windows, you could just go to C:\Program Files and you would find what you need. In Ubuntu, you must use search to find something you need. Maybe I am ...
26
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7answers
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Copy directory contents using 'cp' command

How do you copy all the contents of one directory into another? For example: $ cd /home/newuser $ cp -a /backup/olduser/* . The problem with the above is that the globing pattern '*' matches the ...
26
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3answers
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Why does a failed linux login take so long? [duplicate]

Possible Duplicate: Why would an incorrect password attempt take a lot longer to process than a correct one? When you get the correct login credentials, you are logged in immediately. When ...
26
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7answers
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ls -d is not displaying directories. Is there a way to get ls to only display directories instead of files and directories

Is there a way to get ls to only display directories instead of files and directories From the man page. -d, --directory list directory entries instead of contents, and do not ...
26
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7answers
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How can I keep a process alive after closing the putty session?

I am using putty to interact with Linux server. I have started a process using putty. The process is running and will take 5-6 hours. I want that process to keep running after I close the putty ...
26
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7answers
173k views

How to set current time on Linux?

Why is the output of the following commands different? root@vmi2115:/var# hwclock Sun 26 Jun 2011 01:21:38 PM CEST -0.273230 seconds root@vmi2495:/var# date Sun Jun 26 15:21:39 CEST 2011 ...
26
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7answers
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Why create many partitions?

I have noticed that when installing Ubuntu some people create multiple partitions for directories. Like one for root, one for home, one for boot. What is the advantage to doing this over installing ...
26
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3answers
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What's all those users in the /etc/passwd file?

The /etc/passwd is supposed to have a line for every user on the system. Amongst the common username and root there is a bunch of other users. Some examples: timidity:x:114:127:TiMidity++ MIDI ...
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10answers
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How to Remove the Last 2 Lines of a Very Large File

I have a very large file ~400G, and I need to remove the last 2 lines from it. I tried to use sed, but it ran for hours before I gave up. Is there a quick way of doing this, or am I stuck with sed?
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5answers
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How to reinstall GRUB2 EFI?

After successfully updating my bios, something went wrong and I ended up with a blinking cursor on the top left corner of a black screen. No errors, no nothing. The bios now only listed a SATA: ...
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6answers
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How can I diff two XML files?

On Linux, how could I generate a diff between two XML files? Ideally, I would like to be able configure it to some things strict, or loosen some things, like whitespace, or attribute order. I'll ...
26
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1answer
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Why does deleting from the command line take significantly less time than from a GUI?

Something I wondered about as I was deleting a dozen or so images from my computer: With a quick rm -rf command on the directory's contents, all the images were gone in a snap. When I drag the same ...
26
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1answer
3k views

How urgent is a *** System restart required *** for security?

To learn a bit of server administration I've set up a simple Ubuntu 14.04 server on which I run a personal website. I've set it to automatically install security updates, but leave out the other ...
26
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2answers
10k views

How to run a minimal Linux inside a running 64-bit Windows 7

On my previous Windows Vista laptop, I used to run Portable Ubuntu Remix for Windows, which is based on coLinux, like the similar andLinux. This worked fairly well with limited system resources (a ...
25
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3answers
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How accurate is `md5sum`?

When using md5sum to verify the integrity of a file, how accurate is the process? Does a verified MD5 mean that EVERY bit is exactly the same, or is there a threshold that must be broken before ...
25
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14answers
29k views

Linux command to repeat a string n times

Is there any built-in linux command that allows to output a string that is n times an input string??
25
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2answers
16k views

What does Linux do with existing files in a mount point?

If I attempt to mount a folder that already has files in it, does linux give me an error message or go ahead and show both the mounted filesystem and the files that were already in the folder?
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4answers
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How to lock a file against deletion but still make it writeable?

I want to make a file locked against deletion but still be writeable. How do I do this? The file in question is a Truecrypt volume as a file on a NAS SMB Network share, so I don't want to ...
25
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3answers
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How to wget a file with correct name when redirected?

So after some time of searching on google and superuser (and scanning man pages) I was unable to find an answer to something that (I think) should be simple: If you go here: ...
25
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4answers
30k views

Delete matching files in all subdirectories

How can I remove all .swp files in all of my subdirectories under Linux?
25
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7answers
36k views

How do I fix the Shellshock security vulnerability in debian testing/jessie?

The test command x='() { :;}; echo vulnerable' bash shows that my Debian 8 (Jessie) installation is vulnerable, even with the latest updates. Research shows that there's a patch for stable and ...
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4answers
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Looping Through Subdirectories and Running a Command in Each

I have a set of repositories sorted into directories based on their VCS (Git, Mercurial, SVN). With Subversion I was able to run svn update * in the parent directory and it would loop through each ...
25
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8answers
54k views

How to get parent PID of a given process in GNU/Linux from command line?

Resolved before asked: cat /proc/1111/status | grep PPid
25
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3answers
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How do I get out my embedded Windows 8 key from a Linux environment?

I have seen other SuperUser questions on this topic: How to find Windows 8 product key? | How to find Windows 8 OEM product key? However, all of the answers assume you have Windows 8 running. I've ...
25
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3answers
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In Linux, how do I truncate command-line output?

If I grep -nr sumthin * in my source code directory, it also spews out very long lines from minified JavaScript or CSS files. I want to get just the first 80 characters per line. For example, a ...
25
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4answers
12k views

How to: Unlimited Bash/shell history?

Is there a way to define an unlimited history in Bash ?
25
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4answers
8k views

bash watch command with colors preserved

From man watch: Non-printing characters are stripped from program output. Use "cat -v" as part of the command pipeline if you want to see them. So how do I use cat -v if I want to see the ...
25
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2answers
23k views

Can GNU Grep output a selected group?

Is it possible to use GNU grep to get a matched group from an expression? Example: echo "foo 'bar'" | grep -oE "'([^']+)'" Which would output "'bar'". But I would like to get just "bar", without ...
25
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2answers
9k views

What's the difference between “adduser” and “useradd”?

I wonder: Why are there these two commands on Debian Linux, with very similar names and functionality? This has always been confusing for me. Is any of them superior to another? Why aren't they ...
25
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3answers
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How do I log out of `sudo su`?

I'm using sudo su to start mysql and do some homework with it. When I finish with mysql (or any other command), then I'm still in sudo. How do I "log out", so my prompt changes back from # to $?
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5answers
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How can I know the absolute path of a running process?

If I have multiple copies of the same app on the disk, and only one is running, as I can see with ps, how can I know the absolute path to distinguish from the others?
25
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4answers
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Is there a linux command like mv but with regex?

For example I want to mv (.*?).sql $1.php, is there a command that lets me specify renaming patterns?
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5answers
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VirtualBox from an existing partition

I installed VirtualBox on my Ubuntu Hardy Heron installation, and I would like to use it to virtualize Windows for those rare occasions that I actually need to do something there. Unfortunately, I ...
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15answers
52k views

How do I check whether I am using KDE or Gnome?

or maybe something else? I am using Redhat OS.
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6answers
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play mp3 or wav file via Linux command line

I would like to make an alarm system backed by a Ubuntu (no graphical interface) box, which plays various announcement and alarm audio tracks (.mp3 or .wav) via the command line. For example: $ ...