nux's questions

I have a directory name foo located in ~/Desktop. Suppose I want to create a directory from a terminal with same name and in the same location. When I tried mkdir it gave an error:

mkdir: cannot create directory `/home/nux/Desktop/foo': File exists

Thats makes sense, but I want to replace foo if exists. I looked through man mkdir but there isn't any option that do that.

So how to overwrite foo directory?

Why doesn't mkdir have an option to do this?

When reading the content of a script, I found something like:

echo "An Example" > !$

So I wonder what does !$ mean in bash .

I need to find the creation time of a file, when I read some articles about this issue, all mentioned that there is no solution (like Site1, Site2).

When I tried the stat command, it states Birth: -.

So how can I find the creation time of a file?

I have a directory that contains thousands of files, some of them are hidden.

The command ls -a list all files, including hidden ones, but I need just to list hidden files.

What command should I use?

How to install CPU-G on Ubuntu , so i can use it to view information about my desktop hardware .

I have tried to copy a file test.txt to multiple directories with one command:

cp ~/test.txt ~/folder1 ~/folder2

But I didn't succeed. Is there a way to do that in one command so I can copy a file or even a folder to multiple directories?

Is there a command that I can verify by its output the speed of my NIC and some information about its characteristics such as duplex full or half .

I have a directory containing bunch of .txt files , I need a command to rename these files by one command , so their name will be : file1.txt , file2.txt, file3.txt , etc .

Any Help ?

Is there a way to know who is pinging my PC on my network? Is it possible to monitor all ICMP packets? How can I do that?

My question is if someone hacked privileges on /etc/shadow file , can he crack the passwords of the system users.

If yes , how can i secure more my passwords and how to make it difficult on a cracker to easily crack my users passwords .

Any Suggestion?

My understanding of UIDs is that is a unique positive integer assigned by a Unix-like operating system to each user. Each user is identified to the system by its UID, and user names are generally used only as an interface for humans.

How can two users have the same UID, isn't this a conflict for my system and packages?

root@kdc:~# id test12
uid=1005(test10) gid=1000(server) groups=1005(test10)
root@kdc:~# id test13
uid=1005(test10) gid=1000(server) groups=1005(test10)
root@kdc:~#

I've added two users with same UID and GID: test12 and test13

The output of /etc/passwd:

client@kdc:~$ cat /etc/passwd | grep test12
test12:x:1005:1000::/home/test12:/bin/sh
client@kdc:~$ cat /etc/passwd | grep test13
test13:x:1005:1000::/home/test13:/bin/sh

I added the users by useradd -ou 1005 -g1000 username.

I got confused what is the purpose of this, and can it affect permissions and user logs etc. So now if a user is added with uid=0 and gid=0 will has privileges like a root account?

Is there a command to list a directory total size and then each sub-folder and files inside it .

I also want to sort them by increasing order so that I can see which folder is greater in size.

For privacy I want to disable this feature in Firefox, so that when I open Firefox it loads my homepage, not restore the previous session tabs. How can I do this?

How to list all network cards installed in my Ubuntu using a single terminal command?

I have two groups "Group1" and "Group2"

I have also folder "Folder"

I want to give Group1 read and write permission , while Group2 only read .

Any suggestion ?

Is there a command to show Firefox history from the Terminal ?

without the need to Enter Firefox history graphically .

Is there a way to deny an IP address from connecting to my Pc?

Is there a way to deny an Ip from connecting to specific Port?

I need to add 10 users by a script in Ubuntu 12.04.

That could reduces time by adding users manually , and i can apply this script on other desktop .

Each user will has a specific user and in specific group.

Any idea?

I need a command to list all users as well as commands to add, delete and modify users from terminal - any commands that could help in administrating user accounts easily by terminal.

I need a command to list all open ports in my PC, and another command to close a port.

Any suggestions?

I need to close some applications' port.