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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98
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How do I set up SSH so I don't have to type my password?

How do I set up SSH so I don't have to type my password when connecting to a host?
23
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0answers
22k views

ls -la symbolics… what does that last symbol mean?

Possible Duplicate: what does the @ mean on the output of ls on os x terminal? when I type ls -la I get this familiar output... drwxr-xr-x+ 38 kent staff 1292 Nov 6 11:09 . ...
155
votes
8answers
9k views

What do the parentheses and number after a Unix command or C function mean?

I keep seeing parentheses and a number after a command in Unix or Linux or C function. For example: man(8), ftok(2), mount(8), etc. What do these mean? I see them in man too.
24
votes
1answer
3k views

Is there a way to make bash more TAB friendly?

I use bash on both my Mac and as my cygwin shell. Overall, I'm quite pleased with it. My one complaint however is that its TAB completion isn't as good as Windows Command Line TAB completion. For ...
20
votes
2answers
38k views

Allow specific user permission to read/write my folder

I have a folder /home/samantha/folder that I want to share with the user tom. He can read/write the folder. How do I do that? chown wouldn't do it because I still want to be able to be the owner of ...
10
votes
3answers
15k views

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, ...
22
votes
6answers
1k views

Learning the basics of Linux/Unix [closed]

I would like to learn the basics of Linux; In contrast to tutorials that teach how to do common tasks with Ubuntu or something. I'm looking for a structured introduction, not a reference. Also I would ...
27
votes
9answers
24k views

How Unix is Mac OS X? [closed]

From my limited knowledge: The Unix OS coder assumes the user knows what they're doing etc. versus the Apple's you can only do it the way you are allowed to do it, etc. Compared to other variations ...
112
votes
17answers
56k views

How to execute a command whenever a file changes?

I want a quick and simple way to execute a command whenever a file changes. I want something very simple, something I will leave running on a terminal and close it whenever I'm finished working with ...
28
votes
10answers
19k views

Bash: Reset and Clear Commands

I have been using the command: reset to clear my terminal. Although I am pretty sure this is not what I should be doing. Reset, as the name suggests resets your entire terminal (changes lots of ...
3
votes
1answer
11k views

How to change user in winSCP?

I'm using winSCP to access Unix computers. How can I change user after I have logged into a Unix server using winSCP? E.g. I have personal account in unix computer A. I can log into this comp using ...
175
votes
12answers
28k views

How can I change to the previous directory instead of going up?

I currently spend a lot of my working hours moving back and forth between two paths which are very far down the tree and divert from each other at root. It strikes me that my life would be a lot ...
133
votes
8answers
121k views

What is the “You have new mail” message in Linux/UNIX?

Sometimes, when I log into a box and 'su' to root, I get a cute little message saying I have mail (thank GOD it's not AOL). Where is this mail? What does it contain? Who/What sent it? How important ...
45
votes
3answers
74k 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 ...
33
votes
3answers
6k 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 ...
16
votes
3answers
6k views

Use GNU screen as login “shell”

What's the best way to have screen automatically run when you open a new shell, whether by login, xterm, or anything else? I see the most common recommendation is to put exec screen in your regular ...
6
votes
2answers
24k views

How do I reset the $PATH variable on Mac OS X?

I've messed up my path variable, and now some apps that I run raise errors saying Command Not Found (error 127) for commands like date and sleep. These commands work fine when executed directly in the ...
11
votes
2answers
7k views

What does the @ in ls -al mean? [duplicate]

Possible Duplicate: ls -la symbolics… what does that last symbol mean? What does the @ in the below execution of ls -al mean? atom:Lib fak$ ls -al total 1056 drwxr-xr-x 5 fak staff ...
13
votes
2answers
3k views

Unix: Files starting with a dash, -

Ok, I have a bunch of files starting with a dash, -. Which is not so good... and I want to rename them. In my particular case I would just like to put a character in front of them. I found the ...
7
votes
4answers
5k views

Keep a program running after closing a console, after the program has started [duplicate]

Possible Duplicate: How do I detach a process from Terminal, entirely? I've a program running in a Unix console on a remote Unix computer. I (stupidly) didn't run it using nohup &, and ...
10
votes
3answers
2k views

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 ...
10
votes
6answers
2k views

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?
51
votes
2answers
27k views

Why does Windows use backslashes for paths and Unix forward slashes?

It annoys me having used Unix in college and now working on the Windows side. What's the history behind this decision? Anyone know why it worked out this way?
41
votes
11answers
7k views

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

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 ...
49
votes
3answers
105k views

How can I make chown work recursively?

I've got a directory called pdfs that contains a bunch of sub- and sub-sub-directories. I want to change ownership on all PDF files in all of the subfolders. I just tried this: chown -R ...
28
votes
3answers
48k views

How do I make sudo preserve my environment variables?

Using sudo 1.7.4p4 on Solaris 5.10 and sudo 1.6.7p5 on RHEL4 u6 I can't see how to preserve my environment variables, for instance $PYTHONPATH. I've added this line to sudoers, but it doesn't make any ...
10
votes
2answers
9k views

Understanding top command in unix

When I run top -c command on my UNIX box I get the output below: top - 03:09:34 up 5 days, 6:14, 1 user, load average: 0.00, 0.00, 0.00 Tasks: 175 total, 1 running, 174 sleeping, 0 stopped, ...
2
votes
6answers
7k views

Automatically restart a Unix job if it goes down?

I have a job that I would like to "daemonize" on Unix: I want it to come up when the computer boots, and I want it to restart if it goes down. A simple way to do this is to setup a cronjob that runs ...
22
votes
6answers
3k views

What is the general consensus on “Useless use of cat”?

When I pipe multiple unix commands such as grep, sed, tr etc. I tend to specify the input file that is being processed using cat. So something like cat file | grep ... | awk ... | sed ... . But ...
18
votes
9answers
11k views

Is Mac OS X open source?

I learned recently (on superuser) that Mac OS X uses the bash shell. I also know that OS X has a UNIX core. I was searching for information about OS X and Open Source on google, but what I found was ...
7
votes
3answers
3k views

Why should the size of the swap partition be double of the RAM size?

Why is it recommended that the swap partition size be double that of the RAM size? Specifically, why would I need to store data stored in the RAM twice??
1
vote
1answer
199 views

What are the numbers in parentheses in the names of unix tools? [duplicate]

Possible Duplicate: what does crypt(3) and whatnot mean I'm talking about, e.g. in the git Manual pages, on the git(1) page, See gittutorial(7) to get started, or git-add(1) ...
1
vote
3answers
2k views

Modification of files with 777 permissions but not with 755 permissions?

I can modify the files with 777 permissions, but not with 755. I do it by sourcing some sed commands. I find it odd because I can modify the files with even 700 permissions in Vim. Why is it not ...
44
votes
12answers
55k 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): ...
44
votes
4answers
146k views

What is the .bashrc file?

Unix shells when starting read the .bashrc file and execute commands written in it. What is this file and what does it execute?
62
votes
12answers
5k views

What command do I need to use to remove a file called `-rf`?

I did something crazy at some point that created a file called -rf on my filesystem. Now I can't figure out how to delete it... I've tried: rm "-rf" rm \-rf These just exit immediately, arrgh! ...
12
votes
3answers
25k views

Copy list of files

I have a list of files separated by spaces in a file list.txt. I'd like to copy them to a new folder. I tried to do: cp `cat list.txt` new_folder but it did not work. How would you do this ? ...
56
votes
8answers
15k views

Why is “Everything is a file” unique to the Unix operating systems?

I often hear people say "Unix's unique philosophy is that it treats everything as a file" or "In Unix, everything is a file". But I've never heard anyone explain why it is unique to Unix. So, why is ...
24
votes
5answers
14k views

How can I trigger a notification when a job/process ends?

The place I work at has commands that take a long time to execute. Is there a command/utility that I can use to notify me when the command execution is over? It could be a popup window or maybe a ...
16
votes
5answers
8k views

Mac OS X: at command not working

I am going to schedule a job by using at command. Here I tried the following command: $ at now + 1 minute echo 'Test at command' <EOD> I saw the job is scheduled by using at -l. However, I ...
37
votes
4answers
10k views

What is the origin of the UNIX $ (dollar) prompt?

The UNIX prompt uses a $ symbol to indicate that your input is expected. I was wondering why this symbol was chosen -- if there is a reason. Dollar just seems a little unexpected. A > would have been ...
43
votes
3answers
29k 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 ...
29
votes
8answers
13k views

Rename a group of files with one command

If I have a group of files with a .htm extention, how can I rename them all to .html? mv *.htm *.html does not work.
21
votes
4answers
57k views

How to gzip multiple files into one gz file?

I have 100 files: cvd1.txt cvd2.txt ... cvd100.txt How to gzip 100 files into one .gz file so that after I gunzip it, I should have cvd1.txt, cvd2.txt ... cvd100.txt separately? Thanks for your ...
11
votes
2answers
14k views

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 ...
6
votes
3answers
5k views

List all unique extensions for files contained in a directory

I would like to see all the unique extension of files contained in a certain directory. What is the command to do that in bash? One could use find . -type f to get all the files in the current ...
3
votes
4answers
4k views

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 ...
19
votes
5answers
17k views

tar – extract discarding directory structure

unzip has a nifty option -j, whereby the directory structure of the archive is discarded, and all files are extracted into the same directory. Is there a way of making tar work in the same way? ...
16
votes
2answers
9k views

How does one switch between windows on VIM?

I'm using both Vim and MacVim (or well, trying to). I installed the Tagbar plugin but find it impossible to switch to the actual Tagbar window to make my selection. I've been reading loads about ...
10
votes
5answers
4k views

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 ...