Unix is a multitasking, multi-user computer operating system originally developed in 1969 by a group of AT&T employees at Bell Labs.

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How to keep program running after SSH disconnection? [duplicate]

Possible Duplicates: Keep a program running after closing a console, after the program has started How can I use ssh to run a command on a remote Unix machine and exit before the command ...
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How to jump back to the first character in *nix command line?

When writing a long command in the *nix command line and having to go back to the first character, in order to add something at the beginning (for instance a nohup, when you realize the process will ...
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What does kill -3 mean?

I know kill -9 mean, but anyone can explain what does kill -3 mean? Any special signal it sends out?
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How to run commands as in a queue

I need to do a lot of copying of various files to various folders. I can add all my copy commands to a bash script and then run that, but then I must wait until it finishes if I want to add more ...
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Bash Man Page: kill <pid> vs kill -9 <pid>

My man page does not document the difference between kill <pid> and kill -9 <pid> Since these do different things why is the -9 not documented in the kill manpage? I thought maybe ...
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8answers
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Tell `ls` to print only the base filename

This is the default behaviour of ls ls /net/nas/data/languages/pypm/sites/rex/free/2.6/*/pool/v/vi/virtual*1.4.4*pypm ...
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795 views

Why does redirecting the output of a file to itself produce a blank file?

Why does redirecting the output of a file to itself produce a blank file? Stated in Bash, why do less foo.txt > foo.txt and fold foo.txt > foo.txt produce an empty foo.txt? Since an ...
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4answers
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Terminal Vs. Shell [duplicate]

Possible Duplicate: What are the differences between shell , console & terminal? This probably sounds like a stupid question but I'm having a lot of trouble clearly differentiating ...
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How to call bash functions

Maybe I am looking at this the wrong way.. But here I what I am trying to do. Do most of my work with Java but just switched to a unix (bash) environment. I am doing this: [~/Desktop/bashPlay]% ...
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“Detach” and “Reattach” xterms across X sessions?

Is there a way to save/detach an xterm (or another window), and reopen/load/reattach it on a different X session on the same machine ? What I'm trying to achieve is "move" running xterms between two ...
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Making Linux shell prompt show last return value

I'm currently on a Linux machine and the shell prompt is showing me the last return value and number of executed commands (picture included, with these numbers shown in purple). My own computer ...
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What is a “pipe” and how can it be “broken”?

I've gotten the "broken pipe" error from Xcode one time too many. I'm now curious to know exactly what a pipe is. What is the concept of a "pipe" and how can it be "broken"?
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Map “untar” to tar xvfz?

How can I map 'untar' as a command to 'tar -xvfz' ? Sorry, but I almost always forget the arguments necessary to 'tar' for this operation.
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How to read Unix usage

I did some searching, but I cannot find documentation on how Unix usage works. I know something (mostly through trial and error) but, for example, how do I know that /usr/bin/ls ...
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Advantages of cat'ing file and piping to grep

Are there any additional advantages of cat'ing a file and piping it to grep, besides convenience? The convenience being that, when I retrieve commands such as those below from my history, the cursor ...
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Is it better to always copy and delete, rather than move?

Generally speaking, I find myself panicking when I realise that if I cancel a file move, it could cause the target or source to be incomplete. This question applies to Windows and Unix-based ...
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Sorting human readable file sizes

How can I sort a list using a human-readable file-size sort, numerical sort that takes size identifier (G,M,K) into account? Can I sort "du -sh" output for example? Problem: Consider the problem of ...
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5answers
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Store the output of date and watch command to a file

I am a newbie to linux and I am trying to watch a command and try to log it into a file. I tried watch -t -n 10 "(date '+TIME:%H:%M:%S' ; ps aux | grep "pattern" | wc -l)" >> logfile and am ...
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Who deals with the star * in echo *

Who deals (interprets) the * in echo * Does the echo see the star or the shell take care about it and return a list of filename .. What about cp temp temp*
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How to delete all but one file in Unix? [duplicate]

Possible Duplicate: How to delete all files in a directory except some? How to delete all but one(or some) file in Unix? Something like rm -rf -ignore myfile.txt *
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Linux mv command moved data to an unknown location?

I accidentally executed this command in SSH: mv /var/www/vhosts/website/httpdocs/magento/* Now all the data in the magento dir is gone. Does anyone know where it moved to? Thanks!
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awk, mawk, nawk, gawk… WHAT?

I've just started learning awk and I'm a little confused about all those versions around. Is there any "version" which is found on all Unix-like systems? Like, you know, plain vi? Does the standard ...
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How can I use ssh to run a command on a remote Unix machine and exit before the command completes?

How can I use ssh to run a command on a Unix machine and exit before the command completes? For instance, if I type ssh localhost 'sleep 60 &' ssh hangs on my terminal until sleep completes, ...
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How to make files created in a directory owned by directory group?

Is there a way, on Linux, to cause all new files created in a directory to be owned by the directory's group instead of the creating user's group?
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Subsystem for UNIX-based Applications in Windows 7

Noticed a thing called Subsystem for UNIX-based Applications in the Turn Windows features on and off dialog under Windows 7. Never seen it before, and it seems interesting. What exactly is it really? ...
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Unix: Slash after directory names or not

What is the difference between the following commands? mv foo bar mv foo/ bar/ mv foo/ bar mv foo bar/ Or is there no difference? Or does it depend on the command being used? Think for example I ...
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Vim highlighting for specific file types (where to put syntax files, vim events, line to put into vimrc)

I have defined a file time jak.vim to offer custom highlighting when I take notes, however it is being applied to some files that do not have the .jak extension. Specifically a file named ...
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Console commands to change virtual ttys in Linux and OpenBSD

In Linux one presses Alt-F1, Alt-F2 etc to change virtual ttys. In OpenBSD one shall use Ctrl-Alt-F1 etc instead. My question is if there are console commands for these two operating systems that ...
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1answer
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Linux - alternative places where to store pid file instead of /var/run

As written in the title, where should I let the init script write the pid file? are there any standard paths I should choose instead of the /var/run ? Could /tmp be a good place where to store it or ...
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1answer
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Does rsync delete files, folders at destination by default?

Files Suppose that /foo/src contains only A.c and that /foo/dest contains both A.c and B.c. And suppose I run the following command: rsync /foo/src/ /foo/dest Will rsync erase B.c? Folders Now ...
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How do I set an environmental variable for a GNOME session?

On my system, for apps that use SDL, I need to set an environmental variable: export SDL_AUDIODRIVER=alsa to get the sound to work properly. How do I set up my GNOME session so that this variable ...
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What is the difference between Unix and Linux? [duplicate]

I want to know what the actual difference between Unix and Linux is. Do they share the same kernel? Is Linux built on Unix? Do programs written for Linux work on Unix and vice-versa?
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Best practices to alias the rm command and make it safer

Some time ago I erroneously deleted my home folder because I ran a rm -rf * on the wrong terminal, whose working directory was the home folder! I wish I had an alias for the rm command, but it was ...
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Calling a script with ./bla.sh vs. . bla.sh

Can anybody explain to me what the shell does in the two examples A) and B) below? It obviously behaves differently, but I can't find out why the output is different. Example: Let's have a script in ...
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How is \$ being interpreted by grep?

When I write $ grep \$ then whatever I type on terminal, is matched and printed on terminal. How is \$ being interpreted?
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Mass renaming, *nix version

I was looking for a way to rename a huge number of similarly-named files, much like this one (a Windows-related question) except that I'm using *nix (Ubuntu and FreeBSD, separately). Just to sum up, ...
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What is the official installer for Unix packages on Mac OS?

I'm a bit confused about the installation of standard Unix packages on Mac OS X. For example, I have /usr/bin/svn, which is SVN v.1.4.4, but FinkCommander says svn is not installed. The same holds for ...
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downloading file using scp command

I have a centos server lets say with ip: 1.2.3.4. I want to download a file from 1.2.3.4 at path /root/pc/filename.rar to my localhost host (current pc). What command I need to download that file? I ...
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How to display Unix time in the timestamp format?

I'm looking for a way to display my time in Debian Linux as a timestamp, e.g. 1279628325 I can't find any options to do that with the date command. Any ideas?
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In Unix “less”, can I jump to the next line that does NOT contain X?

In the Unix less tool, is it possible to jump to the next line that does not contain a certain expression? I sometimes have to look through files that contain thousands of similar adjacent lines ...
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SSH: completly disabling password authentication

is there a way to disable password authentication completely? The command line is the following: ssh -o KbdInteractiveAuthentication=no -o PasswordAuthentication=no machine" it STILL asks for a ...
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How Many Unix Groups Can A User Be A Member Of?

We've recently run into a situation at a group-happy site where some group memberships are not being picked up. I seem to remember that there is an upper limit to the number of groups that a user can ...
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Is there a way to edit files inside of a zip file without explicitly extracting them first?

I sometimes need to make changes to a .zip or .jar file, so I usually move the file to /tmp, extract all the files with unzip, edit a few files, and then re-zip up the files. This works, but it can ...
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ZSH tab completion of git commands is very slow. How can I turn it off?

If I type: rm <TAB> I'll see possible completions almost instantly. However, if I type: git rm <TAB> It'll hang for several seconds if it's in a git repo, or fail to show any ...
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3answers
2k views

Why are there short and long alternatives for command line options?

Most unixoid commands feature short and long alternatives for command line options, like ls -a and ls --all, or ls -A and ls --almost-all. Why do those two ways exist? One is shorter to type, the ...
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Is it possible to mount a .tar file?

The only result of any import when I searched for this was from 2001. In the intervening decade, have any tools/methods for mounting a tar file as a filesystem (perhaps utilizing fuse) been created? ...
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Opposite of tail: all lines except the last n lines

How can I discard the last n lines of a file with a unix command line filter? That would be sort of the opposite of tail: tail discards the first n lines but pipes the rest through, but I want the ...
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How can I check the user command history in Unix?

I know the 'history' command give me a list of the commands I have typed into the Unix terminal. How do I see the command history for all of the users currently logged onto the system?
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How to move folder in unix using mv, only when target is on the same drive

I need to move a folder using unix mv command, but only if the target is in the same drive or the same filesystem. What would be the best approach?
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groupadd/useradd not found on Mac OSX

Does anyone know how to add unix groupadd command on Mac OSX 10.5? I'm trying to do man on groupadd and useradd commands but it doesn't seem to exist.