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

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60
votes
9answers
22k 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 ...
60
votes
10answers
165k views

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 ...
60
votes
3answers
12k 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 ...
59
votes
8answers
183k views

How to upload one file by FTP from command line?

I need to upload a single file to FTP server from Ubuntu. This operation should be done in a script (in non-interactive mode). What is the right syntax for ftp? I'm trying this, to no avail: $ ftp -...
59
votes
2answers
64k 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 /media/...
57
votes
2answers
15k views

The MD5 hash value is different from Bash and PHP [duplicate]

I tried to generate the MD5 sum (using md5sum) of a string, "hello". I tried out different methods as the md5sum tool in Linux, PHP's MD5() function as well as various online text to md5sum ...
57
votes
6answers
37k 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 ...
57
votes
3answers
45k 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.
57
votes
13answers
61k 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 ...
57
votes
4answers
56k views

What does the dot mean at the end of `-rw-r--r--`? How do you set it with `chmod`?

I see that some of the files in my directories under Linux have a . at the end of the permissions listing. What does the dot mean at the end of -rw-r--r--? How do you set it with chmod?
57
votes
2answers
34k views

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 ...
56
votes
4answers
5k views

Is a file system just the layout of folders?

I have used Windows since childhood, and when I hear the phrase "Windows filesystem" I think of directories (folders) within directories, a folder called SYSTEM, a folder called PROGRAM FILES etc. Is ...
56
votes
7answers
54k 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 ...
56
votes
6answers
67k 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?
56
votes
4answers
45k views

What does load average mean in unix/linux?

If I run uptime, I get something like this: 10:50:30 up 366 days, 23:27, 1 user, load average: 1.27, 2.06, 1.54 What do those numbers on the end mean? The man page tells me it's "the load ...
55
votes
6answers
3k views

Alternative for “tail -f” that follows filename

I have some logs being generated using a timed rotating file logger. This logs to a file called tool.log, and at midnight, moves this to tool.log.<date> and starts a new tool.log. I have a tail ...
55
votes
7answers
84k 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: ...
55
votes
10answers
80k 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, ..., ...
55
votes
5answers
137k 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 manually....
55
votes
5answers
42k 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?
54
votes
6answers
4k views

What is a simple way to let a command run for 5 minutes? [duplicate]

Is there an easy way to let a specific command (only terminable through Ctrl-C) run for 5 minutes automatically? For example: minute-command 5-minutes ping www.google.com or any other command that ...
54
votes
6answers
150k 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 ...
54
votes
1answer
100k 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 ...
54
votes
4answers
5k views

How does /proc/* work?

There are many files in /proc, like /proc/cpuinfo, /proc/meminfo, /proc/devices and so on, which, when opened, return system information. These files do not seem to have any existence in reality, as ...
54
votes
5answers
41k 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. ...
53
votes
2answers
85k views

Linux unzip command: Option to force overwrite?

I am writing a shell script that unzips a ZIP file into an existing hierarchy of files, potentially overwriting some of the files. The problem is that the unzip command asks for confirmation: replace ...
53
votes
5answers
3k views

How to “unextract” a zip file?

I extracted a zip file into a non-empty folder. The zip file has lots of files and a deep hierarchy, that merged with the existing tree of the target directory. How can I remove the files and ...
52
votes
10answers
69k views

show keys pressed in linux

in windows there is a program called keyboard jedi that shows what keys are pressed on the keyboard. is there an equivalent for linux?
52
votes
5answers
52k 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 ...
52
votes
7answers
81k views

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?
51
votes
9answers
60k 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 ...
51
votes
5answers
32k views

In vim, how can I quickly switch between tabs?

In gnome-terminal, I can just press Alt + (1, 2, 3, etc.) to switch to specific tabs. I can also use Ctrl + (PgUp / PgDn) to cycle through tabs (admittedly less convenient, but it can be remapped). ...
51
votes
8answers
3k views

How do you configure a Windows machine for a Linux user? [closed]

How do you configure a Windows (preferably latest version) machine for a Linux power user, so that s/he can get most out of it?
51
votes
4answers
20k views

less is more? Is more less? I'm so confused

When I first heard their names, I got really confused when I tried to guess what these tools might do, I thought I'd misheard something. What's the difference between more and less, i.e. why ...
51
votes
5answers
39k views

How do you redirect wget to standard out?

I have a crontab that wgets a PHP page every five minutes (just to run some the PHP code), and I want to send the output to standard out. I couldn't find it in the wget manual. I'm looking for ...
51
votes
2answers
148k views

Linux - Mount device with specific user rights

How can I mount a device with specific user rights on start up? I still have some problems figuring it out. I would like to mount the divide with uid=1000 and gid=1000. My current entry to the /etc/...
51
votes
2answers
49k 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 ...
50
votes
14answers
47k views

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?
50
votes
7answers
46k views

How to throttle bandwidth on a Linux network interface?

Is there a way to constrain the bandwidth on a NIC in linux? I'd like to be able to simulate an arbitrarily slow connection.
50
votes
13answers
158k 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?
49
votes
4answers
78k views

How can I create a non-login user?

I'd like to create a user and a group both called subversion on a RHEL 5 system. I looked at the man page for useradd and I guess the command would be just be... useradd subversion However, not ...
49
votes
3answers
8k views

Slight delay when switching modes in vim using tmux or screen

Switching to and from insert mode in Vim is no longer instantaneous since I use tmux. After pressing Esc in insert mode, it takes a noticeable amount of time to actually get out of insert mode. After ...
49
votes
1answer
77k 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)?
49
votes
4answers
123k views

How to update Google chrome in Ubuntu?

How to update Google chrome in Ubuntu?
49
votes
11answers
183k views

PuTTY Network Error: Software caused connection abort

I have a strange problem: When I'm using PuTTY with SSH connecting to a Linux server hosted in VMware on my local Windows 7, I often get the error saying "Network error: Software caused ...
48
votes
11answers
21k views

What is the relationship between Unix, Linux, Ubuntu, Debian and Android?

What is the relationship between Unix, Linux, Ubuntu, and Debian? I suspect they are all Operating Systems that are based upon one another - similar to how Windows is based on DOS. Is my suspicion ...
48
votes
5answers
10k views

What is the equivalent of Linux's “~” (tilde) in Windows?

In Linux, we can go to the user home by entering the tilde (~) character after cd: cd ~ How to do the same in Windows? Each time, I need to type: cd C:\Document and Settings\freewind That's too ...
48
votes
4answers
23k views

How to: Unlimited Bash/shell history?

Is there a way to define an unlimited history in Bash ?
48
votes
3answers
58k 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 ...
48
votes
3answers
29k 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 ":...