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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56
votes
5answers
70k 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 ...
56
votes
12answers
57k 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 ...
56
votes
4answers
53k 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?
56
votes
3answers
30k views

scp between two remote hosts from my (third) pc

I have two remote hosts. host1-> 10.3.0.1 host2-> 10.3.0.2 Both run an ssh server. The ssh server listens on port 22 in host1 and on port 6969 in host2. Now, using my local machine, I need to copy ...
56
votes
10answers
153k 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 ...
56
votes
2answers
32k 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 ...
55
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 ...
55
votes
4answers
32k 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.
55
votes
3answers
43k 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.
55
votes
2answers
95k views

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 ...
55
votes
3answers
11k 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 ...
55
votes
4answers
44k 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 ...
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
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 ...
54
votes
7answers
80k 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: ...
54
votes
8answers
174k 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 ...
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
6answers
51k 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 ...
54
votes
5answers
133k 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 ...
54
votes
7answers
64k 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?
53
votes
10answers
75k 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, ..., ...
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 ...
53
votes
5answers
40k 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?
53
votes
5answers
40k 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. ...
52
votes
1answer
95k 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 ...
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
19k 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 ...
50
votes
6answers
143k 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 ...
50
votes
2answers
79k 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 ...
50
votes
13answers
151k 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?
50
votes
7answers
76k 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?
50
votes
2answers
139k 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 ...
49
votes
9answers
57k 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 ...
49
votes
7answers
45k 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.
49
votes
5answers
49k 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 ...
49
votes
1answer
73k 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)?
48
votes
10answers
63k 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?
48
votes
5answers
36k 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 ...
48
votes
3answers
56k 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
4answers
118k views

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 $?
48
votes
4answers
118k views

How to update Google chrome in Ubuntu?

How to update Google chrome in Ubuntu?
48
votes
11answers
172k 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
2answers
45k 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 ...
47
votes
11answers
20k 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 ...
47
votes
4answers
68k views

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 ...
47
votes
1answer
10k views

If I buy a computer with Windows 8 and Secure Boot, will I still be able to install Linux?

I've heard a lot about how Microsoft is implementing UEFI Secure Boot in Windows 8. Apparently it prevents "unauthorized" bootloaders from running on the computer, to prevent malware. There's a ...
47
votes
1answer
32k 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: ...
47
votes
3answers
27k 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 ...
46
votes
4answers
29k 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). ...
46
votes
5answers
9k 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 ...