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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11answers
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Manually closing a port from commandline

I want to close an open port which is in listening mode between my client and server application. Is there any manual command line option in Linux to close a port ?? NOTE: I came to know that "only ...
45
votes
12answers
115k views

How to recover a removed file under Linux?

By accident, I used rm on a file I didn't want to delete. Is there a way that I can get it back under Linux?
45
votes
3answers
8k views

What does the 'rc' in `.bashrc`, etc. mean?

Well, this is embarrassing. I feel like I just realised I don't know a loyal colleague's name after working with them for 10 years. "Hey, er... *cough!*, thanks for that great job you did on setting ...
44
votes
7answers
59k views

What's the easiest way to sniff TCP traffic data on Linux?

I want a simple way to show all the TCP data (not the TCP headers or anything else) going over any interface on my Linux box. For instance, I want a magical command that if I do: ...
44
votes
8answers
50k views

ffmpeg: create a video from images

Is it possible to use ffmpeg create a video from a set of sequences, where the number does not start from zero? For example, I have some images [test_100.jpg, test_101.jpg, test_102.jpg, ..., ...
44
votes
1answer
44k views

Permission denied when accessing VirtualBox shared folder when member of the vboxsf group

I'm running Ubuntu 11.04 (guest) on Windows 7 (host) with the guest additions installed. I have an auto-mount folder that maps to my D: drive on the host which I can access using sudo ls ...
43
votes
3answers
25k views

How to analyse disk usage in command line linux?

du and df are nice, but I don't know how to filter the data they provide the way I do with SequoiaView. I would like to know which are the largest folders and the largest files in a glance.
43
votes
5answers
112k views

What is this dm-0 device?

While poking around trying to figure out why a Linux -> Linux file transfer is running slower than I think it should, I stumbled across something I'm not familiar with. /dev/dm-0 seems to be my ...
43
votes
3answers
13k views

Tmux - move pane to new window

I know that it's possible in Tmux to 'join' a window as a pane, but is it possible to move a pane to it's own window (tab)? I tried searching it up the man page but couldn't find it. I guess it is ...
43
votes
7answers
15k views

Linux / OS X tar incompatibility – tarballs created on OS X give errors when untarred in Linux

When I tar up files on my Macbook and untar them in Linux, I repeatedly get the following warnings/errors: tar: Ignoring unknown extended header keyword `SCHILY.ino' tar: Ignoring unknown extended ...
43
votes
6answers
39k views

What is the conventional install location for applications in Linux?

I'm currently installing NetBeans, and the default install directory is /home/thomasowens/netbeans-6.8. I'm not a fan of that location, so I'm looking at /etc, /bin, /usr/bin, and /sbin. Does Linux ...
43
votes
6answers
24k views

Better Ubuntu Fonts

I have been using Ubuntu for a while. I like it. I like it a lot. But once in a while, when I switch to Windows, I feel better because I really like the font. It feels really much pleasant to watch ...
42
votes
2answers
5k views

what is the difference between “command && command” and “command ; command”

I see these two usage on Ubuntu "command && command" and "command ; command", e.g. apt-get update && apt-get upgrade What would differ if I use apt-get update; apt-get upgrade? I ...
42
votes
7answers
63k views

How to list folders using bash commands?

Is there any way to list just the folders in a directory using bash commands? ( as the ls command lists all the files and folders )
42
votes
3answers
100k 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 ...
42
votes
6answers
102k views

How do I restart Linux (Ubuntu) from the command-line?

Because of my problem with mouse-clicks being ignored in Ubuntu, I want to restart from the command-line. (I have an open Terminal, and the keyboard is not ignored.) How do I restart a computer ...
42
votes
3answers
42k views

How do you check how much power a USB port can deliver?

Some laptops have a special USB port that can deliver more power than the other ones. However it is not always easy to identify which one is the good one, nor how much power it can deliver. So is ...
42
votes
4answers
28k views

check the physical health of a USB stick in Linux

How to check the health status of a USB stick? How do I know that a USB is broken beyand repair, or repairable?
42
votes
5answers
33k views

VirtualBox to use dual monitors

I am am running Kubuntu Hardy Heron, with a dual monitor setup, and have VirtualBox on it running Windows XP in seamless mode. My problem is, I can't get virtualbox to extend to the second monitor. ...
42
votes
5answers
50k views

When should I use /dev/shm/ and when should I use /tmp?

When should I use /dev/shm/ and when should I use /tmp? Can I always rely on them both being there on Unices?
41
votes
9answers
4k views

Why is Bash everywhere (in most if not all Linux distributions)?

Bash is used by default in every Linux distribution I have tried, over alternatives like Z shell (zsh). Is there a technical or historical reason for this?
41
votes
8answers
42k views

Best way to transfer files over a LAN between two Linux computers

I want to transfer files (a music folder) between two Linux computers. After searching for the best way to do this, I've seen that there are lots of ways of doing this. I know this has been asked a ...
41
votes
5answers
21k views

Getting macro keys from a Razer BlackWidow to work on Linux

I picked up a Razer BlackWidow Ultimate that has additional keys meant for macros that are set using a tool that's installed on Windows. I'm assuming that these aren't some fancypants joojoo keys and ...
41
votes
10answers
38k views

Top causes of slow ssh logins

I'd love for one of you smart and helpful folks to post a list of common causes of delays during an ssh login. Specifically, there are 2 spots where I see a range from instantaneous to multi-second ...
41
votes
4answers
39k views

When ssh'ing, how can I set an environment variable on the server that changes from session to session?

When I ssh into a server, how can I pass an environment variable from the client to the server? This environment variable changes between different invocations of ssh so I don't want to overwrite ...
41
votes
2answers
60k views

Where does Google Chrome for Linux store user specific data?

Where does Google Chrome for Linux store user specific data such as bookmarks ? I can't find a .chrome or .google directory under my home directory, any other directory I should look at ?
41
votes
1answer
50k views

What is $* and $# in Linux?

What do the following environment variables in Linux mean? What is $* (dollar sign followed by an asterisk)? What is $# (dollar sign next to a hash mark/number sign/octothorpe/pound sign)?
40
votes
9answers
3k views

How to quickly change the first word in a Bash command?

I would like to improve my workflow a bit with Bash, and I realize I often want to execute the same command to a different executable. Some examples: Git (where I would like to quickly change the ...
40
votes
5answers
49k views

what does the asterisk mean after a filename if you do ls -l

I've done an ls -l inside a directory, and my files are displaying like this : james@nevada:~/development/tools/android-sdk-linux_86/tools$ ll total 9512 drwxr-xr-x 3 james james 4096 2010-05-07 ...
40
votes
5answers
27k views

Is there a way to show notification from bash script in Ubuntu?

Most of the application can show nicely formatted notification on events that appear on top right corner of the screen. I'm about to write a bash script that will do fairy long processing in the ...
40
votes
3answers
32k views

Case Insensitive search from find command?

I am not able to figure out how can I do case-insensitive search using the find command. I tried find . -name -i pattern And it does not work.
40
votes
7answers
10k views

Linux equivalent of Windows Registry

What is the Linux equivalent of Windows Registry? If there is no equivalent or similar structure in Linux, how are the things that are done by the Windows Registry handled in Linux?
39
votes
9answers
47k views

How can you see the actual hard link by ls?

I run ln /a/A /b/B I would like to see at the folder a where the file A points to by ls.
39
votes
8answers
4k views

Why is -r recursive necessary when copying a directory in Linux?

My question is why is it required to use the -r (recursive) flag when making a copy of a directory? I.e., why do this: $ cp -r dir1 copyDir1 When would I not want this behavior when copying a ...
39
votes
1answer
69k views

How do I unzip a tar gz archive to a specific destination?

I want to unpack a .tar.gz file to a specific directory. The archive file is in /root/Documents. I want to unzip it into /root/Desktop/folder. The folder structure in zipped file should be preserved ...
39
votes
3answers
27k views

Ubuntu shutdown fail “* Killing all remaining processes…”

I have a fresh installation of Ubuntu Server. "reboot" works, but shutdown fails on the * Killing all remaining processes... step. I am using: sudo shutdown now After the failure, indicated by ...
39
votes
4answers
22k views

Is there a way to find out what application using most of bandwidth in Linux?

I'm looking for an utility that could show me how much of a bandwidth each process are using. It should just print the data and exit as I want to feed that list into conky.
39
votes
5answers
100k views

Add permanent SSL certificate exception in Chrome (Linux)

I have a problem with a website that has an SSL certificate which doesn't correspond to the website domain. Chrome gives me a warning for this website (and rightly so), which I have to ignore ...
39
votes
4answers
37k views

How can I recursively copy files by file extension, preserving directory structure?

At the Linux command line, I'd like to copy a (very large) set of .txt files from one directory (and its subdirectories) to another. I need the directory structure to stay intact, and I need to ...
38
votes
4answers
12k views

tmux disregarding the configuration file

I just installed tmux on Ubuntu 10.04 and tried to remap the prefix key to C-a by creating the file ~/.tmux.conf with these lines: set-option -g prefix C-a unbind-key C-b When starting tmux, both ...
38
votes
4answers
23k views

How to make cut/copy/paste in GVim on Ubuntu work with Ctrl+X,Ctrl+C,Ctrl+V?

By default, the cut/copy/paste short-cuts in GVim on Ubuntu are: Cut "+x Copy "+y Paste "+gP I would like to use control key combos in GVim, like I use in Firefox and othe gnome ...
38
votes
4answers
53k views

No option to hibernate/shutdown in GNOME 3?

I have installed Fedora 15 Alpha with GNOME 3. Everything is working fine. However, I can't see any option to hibernate or shutdown. In the top panel when I click my user name, I only have one option ...
38
votes
3answers
26k views

How to have Linux ls command show second in time stamp

Something annoying about ls -l command is it shows only hour and minute for a file(like 08:30). How can I see the second portion(like 08:30:44)? man 1 ls and search for 'second' does not give any ...
38
votes
6answers
13k views

What happens if mv is interrupted?

What happens if the Linux mv command is interrupted? Say, I'm moving a whole directory to some other place and interrupt it while it's moving. Will the source directory still be untouched?
38
votes
2answers
45k views

Can I create an SSH user which can access only certain directory?

I have a Virtual Private Server which I can connect to using SSH with my root account, being able to execute any linux command and access all the disk area, obviously. I would like to create another ...
38
votes
11answers
14k views

What's a good solution for file-tagging in linux?

I've been looking for a way to tag my files and search/filter them based on those tags. Here are my (updated) requirements : any file readable by the user can be tagged freely a user can search ...
37
votes
7answers
3k views

How can a Linux OS be “based on” another Linux OS?

I've been looking through quite a number of Linux distros recently to get an idea of what's around, and one phrase that keeps coming up is that "[this OS] is based on [another OS]". For example: ...
37
votes
3answers
21k views

How to add a command in vim editor?

If suppose my source code file name is "foo.c". While editing and debugging i always execute this command:- :!gcc -g foo.c -o foo;gdb foo Can I add a custom command to Vim such that If i type ...
37
votes
2answers
6k views

How to rate-limit a pipe under linux?

Is there a filter which I could use to rate-limit a pipe on linux? If this exists, let call it rate-limit, I want to be able to type in a terminal something like cat /dev/urandom | rate-limit 3 -k | ...
37
votes
1answer
24k views

logrotate configuration file syntax - multiple wildcard entries possible?

Since the man page doesn't answer my question and I don't want to force a rotation cycle, I decided to ask the question here. The man page for logrotate gives the following example: ...