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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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.
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4answers
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Windows vs Linux Local Time?

Ever since I started using Linux in dualboot with Windows I noticed that when I rebooted the machine, the time on the other S.O. was wrong, e.g. it was 12:00 on Linux, then I rebooted and on Windows ...
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10answers
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Is there a way to display a countdown or stopwatch timer in a terminal?

How can I display a real-time countdown timer on the Linux terminal? Is there an existing app or, even better, a one liner to do this?
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6answers
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How do I get ls --color=auto to work on Mac OS X?

I'm trying to move my bash configuration from Ubuntu to Mac OS X and it looks like ls is slightly different. For instance, it won't accept the --color option. How do I get this to work?
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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
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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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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 ...
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2answers
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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 ...
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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 ...
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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
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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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2answers
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Bash: Display each sub-directory size in a list format using 1 line command?

I want to get a list of the directories and their sizes in a list format like how you get when you do a ls -l. The thing is that is there a one line command that can do this? I see others have long ...
26
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7answers
5k views

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 ...
26
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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.
26
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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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3answers
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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 ...
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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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9answers
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How to extract text with OCR from a PDF on Linux?

How do I extract text from a PDF that wasn't built with an index? It's all text, but I can't search or select anything. I'm running Kubuntu, and Okular doesn't have this feature.
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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 ...
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1answer
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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 ...
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1answer
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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 ...
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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 ...
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2answers
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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 ...
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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
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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
15k 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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4answers
29k views

Delete matching files in all subdirectories

How can I remove all .swp files in all of my subdirectories under Linux?
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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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7answers
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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 ...
25
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8answers
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How to get parent PID of a given process in GNU/Linux from command line?

Resolved before asked: cat /proc/1111/status | grep PPid
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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: ...
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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How to: Unlimited Bash/shell history?

Is there a way to define an unlimited history in Bash ?
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4answers
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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
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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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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 ...
25
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2answers
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Mac OSX - Why is /dev/rdisk 20 times faster than /dev/disk

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 ...
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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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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: $ ...
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4answers
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Why is it possible to change the password of an admin user on linux?

A few days ago, a friend of mine, wanted to show me that he can use my linux even if I don't tell him my password. He entered in GRUB, selected the recovery mode option. My first problem is that he ...
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4answers
78k views

How can I add a regular user to the sudoers file?

How can I add more users to the "sudoers" file?
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5answers
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Sudo vs root; any actual differences?

I'm working with a support member for a product, and he insists that I need to be root to install a series of patches, and that sudo won't work; he doesn't provide a reason but seems very firm in his ...
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4answers
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What is effect of CTRL + Z on a unix\Linux application

I was curious and confused that what exactly is the behaviour of CTRl+Z. I know, If a process in running in foreground, and we press ctrl+z, it goes to background. But what exactly happens. Does it ...
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9answers
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How to check the health of a hard drive

My SATA drive started clicking and I was unable to access the data. It was not clicking loudly though, like a drive that has already gone bad. After tightening the connections to the hard drive, it ...
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4answers
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How do you find the parent process of a zombie process?

How do you find the parent process of zombie processes? When the child process is something where the parent is not entirely obvious... Is there some way to list processes in tree format or ...
24
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2answers
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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 ...