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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100
votes
3answers
139k views

How to install local .deb packages with apt-get

Is there a way to install packages store on your HD with apt-get, like a "apt-get install ./package.deb ? If not how to handle the dependencies in a very very easy way.
99
votes
11answers
140k views

How to move all files from current directory to upper directory?

How to move all files from current directory to upper directory in linux? I tried something like mv *.*, but it doesn't work.
98
votes
4answers
72k views

Which linux filesystem works best with SSD

From wiki: The vital TRIM function is supported by the Linux OS starting with 2.6.33 kernel (available early 2010). However, support amongst various filesystems is still inconsistent or not ...
97
votes
11answers
73k views

Undo an “rm -rf ~” command?

I had a folder I didn't want named '~', so from the command line I typed rm -rf ~ and accidentally deleted my home folder (since ~ resolved to /home/username). Is there any way back or do I ...
96
votes
8answers
284k views

Test if a port on a remote system is reachable (without telnet)

In the old days, we used telnet to see if a port on a remote host was open: telnet hostname port would attempt to connect to any port on any host and give you access to the raw TCP stream. These days,...
96
votes
17answers
112k views

Linux utility for finding the largest files/directories [closed]

I'm looking for a program to show me which files/directories occupy the most space, something like: 74% music \- 60% music1 \- 14% music2 12% code 13% other I know that it's possible in KDE3, but ...
94
votes
7answers
98k views

What to do when Ctrl + C can't kill a process?

Ctrl + C doesn't always work to kill the current process (for instance, if that process is busy in certain network operations). In that case, you just see "^C" by your cursor and can't do much else. ...
94
votes
8answers
166k views

How to copy symbolic links?

I have directory that contains some symbolic links: user@host:include$ find .. -type l -ls 4737414 0 lrwxrwxrwx 1 user group 13 Dec 9 13:47 ../k0607-lsi6/camac -> ../../include 4737415 ...
93
votes
3answers
87k views

Finding the process that is using a certain port in Linux

I'd like to be able to find out which process is currently using a certain port in Linux. Is there any way to do this?
90
votes
11answers
88k views

Remove a certain line from Bash history file

How can I remove a certain line from history's database?
89
votes
5answers
45k views

Aptitude vs. apt-get: Which is the recommended (aka the “right”) tool to use?

Some time ago I read that aptitude is the preferred tool for installation on Debian-based systems. But when you search around on how to administer a Debian-based system, then aptitude is rarely ...
88
votes
7answers
145k views

How to check which timezone in Linux?

Is there a way to check which time zone I'm currently in on Linux?
86
votes
4answers
137k views

How can I determine what process has a file open in Linux?

I'd like to determine what process has ownership of a lock-file. The lock-files are simply a file with a specific name that has been created. So, how can I determine what process has a particular ...
84
votes
2answers
185k views

How do I get Java support on Google Chrome in Linux?

Is there a way to run Linux Google Chrome with Java support?
82
votes
9answers
235k views

What is the Linux command to find out hardware info?

I need to find out hardware information for the below items under Linux: CPU (and cores) CPU speed Memory Hard disks OS version Any advice?
82
votes
5answers
208k 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 ...
80
votes
4answers
86k views

How can I find only the executable files under a certain directory in Linux?

How can I find only the executable files under a certain directory in Linux?
79
votes
16answers
97k views

How to synchronize the home folder between multiple computers?

I have three computers at home, and would like to have the /home/ folder tree synchronized between the three. Any files/folders (except those hidden) that are modified/added/removed in one of the ...
78
votes
2answers
74k views

What is the difference between yum, apt-get, rpm, ./configure && make install?

I am new to Linux and am running CentOS. I have come across four ways to update or install software. So far, I've seen: yum install [program] apt-get install [program] rpm -i [program].rpm wget [...
77
votes
4answers
134k views

How to remove a symbolic link to a directory?

I made a symbolic link with the following commmand: ln -s ../test5 I want to remove it now but my rm fails: $ rm -Rf test5/ rm: cannot remove `test5/': Not a directory $ rm test5/ rm: cannot ...
76
votes
5answers
88k views

How to specify level of compression when using tar -zcvf?

I gzip directories very often at work. What I normally do is tar -zcvf file.tar.gz /path/to/directory Is there a way to specify the compression level here? I want to use the best compression ...
75
votes
2answers
8k views

Is “ps -u” Really a Bad Syntax?

IMHO ps -u shows a very useful output, much better than ps -u $USER: $ ps -u Warning: bad syntax, perhaps a bogus '-'? See /usr/share/doc/procps-3.2.8/FAQ USER PID %CPU %MEM VSZ RSS TTY ...
74
votes
3answers
27k views

What's like OSX's pbcopy for Linux

In a terminal in OSX I can pipe output to pbcopy and then go into a web browser and paste it. I tried this in Linux with xcopy but when I switch to the browser it just overwrites the clipboard with ...
73
votes
6answers
204k views

How do I exit an SSH connection?

I’m connecting to a server via SSH to send a message to a socket server using a command like: ssh 181.169.1.2 -p 5566 After the connection is established and I write the message and send it I ...
72
votes
5answers
9k views

What are the functions of the BIOS while the operating system is running?

I always wondered whether the BIOS (apart from conducting POST, starting the bootloader and passing control to the OS after one presses the power button) has any purpose or function while the ...
70
votes
6answers
4k views

How do I perform commands in another folder, without repeating the folder path?

Is there a clever way to do copy and move operations or a command to duplicate a file, without having to do a cd, then mv after, at the same folder? For example, I have to run the following: mv /...
70
votes
6answers
71k views

How can I avoid SSH's host verification for known hosts?

I get the following prompt everytime I try to connect a server using SSH. I type "yes", but is there a way to aovid this? The authenticity of host '111.222.333.444 (111.222.333.444)' can't be ...
70
votes
13answers
100k views

Unix/Linux find and sort by date modified

How can I do a simple find which would order the results by most recently modified? Here is the current find I am using (I am doing a shell escape in PHP, so that is the reasoning for the variables): ...
69
votes
13answers
13k views

How is Linux not prone to viruses, malware and those kinds of things?

How is Linux protected against viruses? This question was a Super User Question of the Week. Read the blog entry for more details or contribute to the blog yourself
69
votes
4answers
14k views

Why would you `cat /dev/null > /var/log/messages`?

On this bash scripting example page the author presents this script: # Cleanup # Run as root, of course. cd /var/log cat /dev/null > messages cat /dev/null > wtmp echo "Log files cleaned up." ...
68
votes
6answers
55k 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 ...
68
votes
4answers
109k views

How to make new file permission inherit from the parent directory?

I have a directory called data. Then I am running a script under the user id 'robot'. robot writes to the data directory and update files inside. The idea is data is open for both me and robot to ...
67
votes
12answers
74k views

How to start GUI linux programs from the command line, but separate from the command line?

I've searched for this before, but have never been able to find an answer. In Windows, if I have a console window open, type winmine, and press enter, Minesweeper will appear, completely separate ...
67
votes
8answers
100k views

How can I tunnel all of my network traffic through SSH?

Whenever I'm using the internet from an insecure location (such as public wifi) I like to use an ssh tunnel (ssh -D port host) to ensure my traffic can't be sniffed. Unfortunately, there seem to be ...
66
votes
5answers
136k views

Linux: find out what process is using all the RAM?

Before actually asking, just to be clear: yes, I know about disk cache, and no, it is not my case :) Sorry, for this preamble :) I'm using CentOS 5. Every application in the system is swapping ...
65
votes
4answers
244k views

Checking what PHP version I'm running on Linux?

I'm running Centos 5 and I need to know what version of PHP I'm running, is there a command for this which I can run?
64
votes
5answers
102k views

Read the contents of a zipped file without extraction? [duplicate]

How can I see the contents of a particular file in an archive without extracting the .zip it is contained within? I'm using the Linux command line.
63
votes
13answers
201k views

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 ...
63
votes
8answers
14k views

Cross-platform file system

I would like my external drives to be readable and writable from Linux, Mac OS X and Windows. FAT32 works, but the 4 GB file size limit is a showstopper these days. Are there any alternatives?
62
votes
8answers
41k views

How can I open a file read-only from command line with emacs/vi/vim

Is there a way to tell emacs/vi/vim (from the command line) that I want to view the file in view-mode or read-only. I know how to open a file as read only if emacs/vi/vim is already running.
62
votes
15answers
56k views

Untar, ungz, gz, tar - how do you remember all the useful options?

I am pretty sure I am not the only one with the following problem: every time I need to uncompress a file in *nix I can't remember all the switches, and end up googling it, which is surprizing ...
62
votes
9answers
89k views

How do I add a user to multiple groups in Ubuntu?

What's the command line utility and the arguments it requires?
62
votes
3answers
33k 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 ...
62
votes
3answers
57k views

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 ...
61
votes
4answers
34k 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.
61
votes
5answers
74k 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 ...
61
votes
11answers
79k views

Automatically mount external drives to /media/LABEL on boot without a user logged in?

This question is similar, but kind of the opposite of what I want. I want external USB drives to be mounted automatically at boot, without anyone logged in, to locations like /media/<label>. I ...
60
votes
13answers
8k views

Is Unix not a PC operating system? [closed]

I am doing my bachelor's degree at a university. In a written assignment, the professor posted the task: "Name three PC operating systems". Well, I went on an included a variety of OSes (Linux, ...
60
votes
4answers
98k 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 ...
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 ...