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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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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3answers
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How to find which files and folders were deleted recently in Linux?

I am having one particular folder (/home/sam/officedocuments) which is having hundreds of folders and files. I think I deleted some files and folders by mistake but I'm not sure. How to find which ...
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6answers
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how to use netstat to show what process is listening on a port

I'm on an OS X mountain lion laptop and have a couple of Vagrant boxes on it. I'm trying to figure out which process is listening on port 8080. My variations produce like a hundred lines but none with ...
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3answers
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What is the fastest and most reliable way to split a 50GB binary file into chunks of 5GB or less, and then reassemble it later?

Our servers are running Ubuntu Linux, and the binary file is a BSON dump of a large MongoDB collection. How reliable is a tool like split? Is there a faster or better way to do this?
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3answers
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Recursively chown all files that are owned by a specific user

Is it possible to find and chown all files that a specific user owns? I did a bunch of things as the wrong user and need to give the correct user ownership of the files. Is there a recursive and ...
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4answers
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What is the reason for rmdir(1) and rm(1) to co-exist?

I use BSD and Linux every day, I have never had a circumstance which I must use rmdir(1) rather than rm(1). What's the purpose of rmdir's existence?
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4answers
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How long is long for the Unix 'file' command?

When you pass a text file to the Unix file command, it might tell you something like: input.txt: UTF-8 Unicode English text, with very long lines Can somebody tell me the minimum number of ...
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3answers
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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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6answers
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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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2answers
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How can I found out if file is alias or symbolic link?

I'm working on a legacy system and I have a bunch of files that are referencing images that are located in other folders. lrwxrwxrwx 1 user nobody 56 Feb 10 2010 t100x100.jpg -> ...
11
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2answers
421 views

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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3answers
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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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3answers
9k views

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 ...
11
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3answers
7k views

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 ...
11
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2answers
2k views

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 ...
11
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1answer
8k views

Aligning columns in output from a UNIX command

I used to know of a command -- an actual command mind you, not sed/awk magic -- that formatted its input to be aligned in columns. For example, if you ran: % echo -e "aaaaa bbbbbbb\ncc ddd" aaaaa ...
11
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1answer
3k views

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
29k views

How do I use my keyfile to sftp transfer data from one server to another

I cant scp, the other server only takes sftp connections. Currently, I am trying to do sftp jay@server.name.com:/files> put -r ~/ -i keyname does not work, just resolves with illegal option -- ...
11
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4answers
12k views

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 ...
11
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7answers
8k views

Screen Capture - command line?

Is there a command line tool out there that can record your computer screen and audio device and then save that to a file?
11
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2answers
143 views

vi / vim abrumpt buffer movements within window

When using :set wrap in vi/vim, the contents of an entire wrapped line are placed in the display buffer upon moving the cursor into a new line, even when navigating through a file by display line ...
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6answers
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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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3answers
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Stop cron from emailing me

How can I stop cron from emailing me the results of jobs I schedule?
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5answers
7k views

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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8answers
3k views

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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5answers
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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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4answers
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How does unix search for executable files?

When a file is executed, how does UNIX search for it? If there are multiple executable files in PATH with the same name which one is preferred? Is current directory included in the search when file is ...
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2answers
4k views

using xargs to cd to a directory

Feeling like an idiot right now. Why does this not work? echo "/some/directory/path" | xargs -n1 cd
10
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2answers
40k views

How to specify group with chmod?

I was asked to add group-wrx permissions to a directory in another user's home folder. I believe what I should do is run chmod 771 -R directoryname in the parent directory. What I can't find ...
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6answers
6k views

Custom vim highlighting

I am editing some xml right now and I have been leaving myself some comments of things to come back to. Like this <!-- Question: bla bla --> I am editing with vim right now and I would like ...
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3answers
11k views

Faster alternatives to “find” and “locate”?

I will like to use "find" and locate" to search for source files in my project, but they take a long time to run. Are there faster alternatives to these programs I don't know about, or ways to speed ...
10
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5answers
138k views

How to run a command file in PuTTY using automatic login in a command prompt?

I am using the following to login automatically to a remote server and then run commands listed in a commands.txt, like this: C:\path\to\putty.exe -load "[Sessionname]" -l [user] -pw [password] -m ...
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3answers
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Can files deleted with rm -rf be recovered?

When I delete folders or files in through osx terminal using the rm -rf, where do they go? I heard that some say they are deleted directly, but some also say it only "remove the link to the file ...
10
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1answer
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Does rm -r follow symbolic links?

If I have symbolic links in some subtree of my directories and decide to recursively removed a driectory and its contents, will that remove items symbolically linked in the tree?
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2answers
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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?
10
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2answers
376 views

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?
10
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1answer
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PowerShell vs. the Unix Shell

I've heard some things about the features of the PowerShell. Some of it seems like typical features of Unix shells. So it seems Powershell includes piping and the commandlets, similar to shell ...
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6answers
12k views

Start a systemd service inside chroot

With init scripts (or with openrc) I alway could run services from a different installation root. but when I run chroot /somepath/to_root /usr/bin/systemctl start someservice I got: Running in ...
10
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1answer
2k views

Where is the STDOUT of a disowned program directed to?

As followup of this question, I would like to know where the STDOUT and STDERR of a program on which I've run disown -h is redirected to.
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2answers
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Practical tips when transitioning to xmonad?

I like the idea and concept of xmonad, however I still keep going back to gnome after an hour or so. This feels like when I first tried to learn vim, but I've gotten past the learning curve point and ...
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5answers
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Export NFS path containing “-” (dash)

I'm in a bit of a pinch with NFS exports file. Specifically, I can't find a way to export a directory containing "-" in the path name. Manual (exports(5)) states: Also, each line may have one or ...
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4answers
4k views

How to download with wget without following links with parameters

I'm trying to download two sites for inclusion on a CD: http://boinc.berkeley.edu/trac/wiki http://www.boinc-wiki.info The problem I'm having is that these are both wikis. So when downloading with ...
10
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1answer
1k views

Is there a way to sort my windows within a screen session?

I use screen and have ssh sessions open to a number of different machines from within my screen session. I'd like to keep them in order, for obvious reasons. Often I'll have to connect to a new ...
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11answers
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Unix: How can I allow only one person to see my folder in the same fs?

I want to give an access to a dir for a friend. He has the access to the file system, where the dir is located. I don't want to set the permissions to all users. How can I allow only a person to see ...
9
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9answers
9k views

grep all .java files in a directory for a particular string

How would I search all .java files for a simple string (not a regex) in the current directory and all sub-directories on Mac OS X? I just want to print a list of file and directory names that match.
9
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13answers
25k views

Scripting: what is the easiest to extact a value in a tag of a XML file?

I want to read a pom.xml ('Project Object Model' of Maven) and extract the version information. Here is an example: <?xml version="1.0" encoding="UTF-8"?><project ...
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3answers
8k views

unix command to delete two folders at once?

Unix command to delete two folders at once? Using rm -rf?
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4answers
9k views

Windows PowerShell equivalent to Unix/Linux `pwd`?

In follow-up to the cmd.exe question, what is the PowerShell equivalent to echo %cd%, or Linux/Unix pwd?
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4answers
1k views

Unix tools: what if a file is named minus something?

I'm always wondering: most GNU/Unix tools take options in the form "minus something", sometimes followed by an argument. What if you got a file named minus something? $ ls -f $ rm -f $ ls -f $ mv -f ...
9
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6answers
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How to grep for special character NUL (^@^@^@)

File: O000000667520994000000074720121112000000N^@^@^@ I used the below command but it doesn't work. grep "^@^@^@" *