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Linux

A free and open-source family of operating systems first started in 1991 and named after its creator, Linus Torvalds.

2,239 Questions

How do you give command line arguments while running a program in Linux?

Different commands can have different syntaxes. The most common format is 'command -a -b -c -d' or 'command -abcd'. Commands with long options will also support the syntax 'command --option --option2 --coption3'.

Who has the most power and privileges in Linux?

That would be "root." THis user can do virtually anything on a Linux system.

Please note, however, that having "maximum permissions" is not actually a good thing. "Ultimate power" may work for comic book villains, it's poor usage on computers. When logged on as root, there's nothing stopping you from annihilating everything on your machine by accident. Linux won't wait for you to be "pretty sure" before happily executing a command.

But by keeping your normal everyday user as a regular user, admittedly likely also in the sudoers file, a command like rm -rfv / can limit the damage to stuff you actually have access to. A lot of people say this is backwards and your personal data is more important... this is true on a personal level, but computer security in most cases is actually NOT about protecting a user's data from its user or intruders, but from keeping the entire system from being compromised through a single user. May seem shortsided from a desktop sense, but for PRODUCTION machines this is absolutely essential.

If you're responsible you'd have yours and all users' data backed up, so that if the unfortunate happens and a user nukes their own home directory you're able to recover it.

To effectively stop user homes from being compromised, it's usually better to mount their individual homes as encrypted file-stored filesystems. Truecrypt is very good for this. If a user isn't logged in, then their home should not be mounted and their home directory file will be very well-encrypted and (If you use hidden volumes.) hidden from intruders who might have your "outer" password.

What is Runtime memory mapping?

Runtime memory mapping pertains to any given geographical?æinformation that is not officially stored memory. It is quite similar to real time in that it is the here and now status. Often times it is fed from satellite.?æ

Write a shell script to print given number in reverse order in Unix?

# Algo:

# 1) Input number n

# 2) Set rev=0, sd=0

# 3) Find single digit in sd as n % 10 it will give (left most digit)

# 4) Construct revrse no as rev * 10 + sd

# 5) Decrment n by 1

# 6) Is n is greater than zero, if yes goto step 3, otherwise next step

# 7) Print rev

#

if [ $# -ne 1 ]

then

echo "Usage: $0 number"

echo " I will find reverse of given number"

echo " For eg. $0 123, I will print 321"

exit 1

fi

n=$1

rev=0

sd=0

while [ $n -gt 0 ]

do

sd=`expr $n % 10`

rev=`expr $rev \* 10 + $sd`

n=`expr $n / 10`

done

echo "Reverse number is $rev"

What is the difference between the ls and ls -al commands?

ls --> will list the files and directories

but

ls -a --> will list the hidden files too,

by

Dhanush M

What type of license does the KDE currently use?

Most of KDE is available under the GNU GPL. Some programs, such as Kate / KWrite are available under the GNU LGPL.

What are the programs 'gdm' and 'kdm' used for?

The GNOME Display Manager (GDM) and KDE Display Manager (KDM) are X display managers that allows a user to start an X session on an X server.

In other words, the display manager shows the login screen when nobody is logged in. After it checks your username and password, it hands off the work to the actual display manager (e,g, GNOME, KDE, Xfce, LXDE).

GDM uses the GTK windowing toolkit, while KDM uses the KDE counterpart, Qt.

What shell does Debian use?

Up to DebianLenny, the default /bin/sh shell was bash. Starting with DebianSqueeze, the default shell will be dash.

What command is used to create a suddirectory and change the current directory and to remove a subdirectory?

If for example we wanted to make i subdirictory called foo

in Linux or UNIX it you use

mkdir foo

to change into it you would use

CD foo

to remove the directory

rmdir foo

but this will only work if the directory is empty

to remove the directory called foo when it is not empty use

rm -rf foo

but please be sure this is what you really want to do.

How can varnish be setup to cache pages?

Varnish can be set up to cache pages by configuring its default caching behavior in the Varnish Configuration Language (VCL). You typically define rules in the vcl_recv subroutine to specify which requests should be cached and under what conditions, such as checking for specific HTTP headers or request methods. In the vcl_backend_response subroutine, you can set the cache duration using the beresp.ttl directive to control how long the cached content remains valid. Finally, ensure that the cache is invalidated appropriately when the underlying content changes, using cache purging strategies.

What is the difference between Linux and Windows in terms of interprocess communication?

They have different models of interprocess communication.

In Windows, processes generally communicate to each other by sending "messages". These messages can carry some data.

In Linux processes can communicate in a number of ways:

* Sending Signals to each other (used for simple signalling, the signals do not carry data). * Using files and network sockets, which allows two-way communication between processes, but involves more programming overhead. * Other IPC (interprocess communication) methods such as System-V message queues, semaphores, and shared memory.

What directories must reside on the same filesytem partition as the root directory?

/bin/ - Binary for all users

/dev/ - Device files

/ect/ - Mounted file systems

/lib/ - Program library

/sbin/ - System Admin Binary

What is xhost plus in Linux?

xhost is server access control program for X.

xhost + means is Access is granted to everyone

How do Windows 7 and Linux talk in a crossover?

You really need to define your terms better. "Talk" I can sort of figure out, but "in a crossover" is a mystery, unless you're talking about a crossover cable. A crossover cable is just a regular UTP ethernet cable with two pairs of wires swapped ("crossed over") in the middle, allowing two devices with 10/100-Base T ports to communicate directly without using a hub or router.

The operating system has pretty much nothing to do with it, other than that both of them need to support the same communications protocol. Anything that uses standard "TCP/IP" protocol meets this requirement.

Are system calls part of kernel?

Yes, they are the interface to kernel functionality. To quote wikipedia: a system call is how a program requests a service from an operating system's kernel that it does not normally have permission to run

What does the cat command do?

cat command concatenates files and prints on the standard output.

1. If you specify only one file it will just display that file

2. If you specify multiple files they will be displayed one after the other.

What would you need to upgrade your Linux kernel?

To upgrade your Linux kernel / compile a newer version, you would need:

1. A working copy of GCC supported by the kernel version.. The latest GCC and the latest kernel version should be fine.

2. Preferably either the ncurses or GTK development libraries. It is possible to configure the kernel without these, but you either need a previous configuration or a lot of patience using the old question/answer configuration script.

3. Enough free space on your computer for the kernel sources. 100 MB should be fine; this isn't really an issue on modern computers.

4. A competent understanding of what components are needed for your computer. Most of the device support should be easy, but many people get confused in the networking section.

What is the difference between the root directory your home directory and your working directory?

The root directory is the top level directory of the entire file system. Every branch starts from there.

The current working directory is where you happen to be in the tree at the moment. If the root is always "/" and my process is in the directory /usr/local/bin/test/data, then the root directory is still "/" and my working directory is currently /usr/local/bin/test/data

Is a copy of an outgoing letter used as a file copy?

I assume by 'outgoing letter' you mean an email? If so, then a copy of the email can be found in the Sent folder, found below Inbox.


Some task that can be done with the Linux conf tool?

what are some of the tasks that can be done with the lunax conf tool?.