Linux Commands Quotes

Filenames

graphical user interfaces make easy tasks easy, while command line interfaces make difficult tasks possible

To understand this first event, you need to know that we rely on Unix and Linux machines to store the thousands of computer files that comprise all the shots of any given film. And on those machines, there is a command—/bin/rm -r -f *—that removes everything on the file system as fast as it can. Hearing that, you can probably anticipate what’s coming: Somehow, by accident, someone used this command on the drives where the Toy Story 2 files were kept. Not just some of the files, either. All of the data that made up the pictures, from objects to backgrounds, from lighting to shading, was dumped out of the system. First, Woody’s hat disappeared. Then his boots. Then he disappeared entirely. One by one, the other characters began to vanish, too: Buzz, Mr. Potato Head, Hamm, Rex. Whole sequences—poof!—were deleted from the drive. Oren

We need to be humble enough to recognize that unforeseen things can and do happen that are nobody’s fault. A good example of this occurred during the making of Toy Story 2. Earlier, when I described the evolution of that movie, I explained that our decision to overhaul the film so late in the game led to a meltdown of our workforce. This meltdown was the big unexpected event, and our response to it became part of our mythology. But about ten months before the reboot was ordered, in the winter of 1998, we’d been hit with a series of three smaller, random events—the first of which would threaten the future of Pixar. To understand this first event, you need to know that we rely on Unix and Linux machines to store the thousands of computer files that comprise all the shots of any given film. And on those machines, there is a command—/bin/rm -r -f *—that removes everything on the file system as fast as it can. Hearing that, you can probably anticipate what’s coming: Somehow, by accident, someone used this command on the drives where the Toy Story 2 files were kept. Not just some of the files, either. All of the data that made up the pictures, from objects to backgrounds, from lighting to shading, was dumped out of the system. First, Woody’s hat disappeared. Then his boots. Then he disappeared entirely. One by one, the other characters began to vanish, too: Buzz, Mr. Potato Head, Hamm, Rex. Whole sequences—poof!—were deleted from the drive. Oren Jacobs, one of the lead technical directors on the movie, remembers watching this occur in real time. At first, he couldn’t believe what he was seeing. Then, he was frantically dialing the phone to reach systems. “Pull out the plug on the Toy Story 2 master machine!” he screamed. When the guy on the other end asked, sensibly, why, Oren screamed louder: “Please, God, just pull it out as fast as you can!” The systems guy moved quickly, but still, two years of work—90 percent of the film—had been erased in a matter of seconds. An hour later, Oren and his boss, Galyn Susman, were in my office, trying to figure out what we would do next. “Don’t worry,” we all reassured each other. “We’ll restore the data from the backup system tonight. We’ll only lose half a day of work.” But then came random event number two: The backup system, we discovered, hadn’t been working correctly. The mechanism we had in place specifically to help us recover from data failures had itself failed. Toy Story 2 was gone and, at this point, the urge to panic was quite real. To reassemble the film would have taken thirty people a solid year. I remember the meeting when, as this devastating reality began to sink in, the company’s leaders gathered in a conference room to discuss our options—of which there seemed to be none. Then, about an hour into our discussion, Galyn Susman, the movie’s supervising technical director, remembered something: “Wait,” she said. “I might have a backup on my home computer.” About six months before, Galyn had had her second baby, which required that she spend more of her time working from home. To make that process more convenient, she’d set up a system that copied the entire film database to her home computer, automatically, once a week. This—our third random event—would be our salvation. Within a minute of her epiphany, Galyn and Oren were in her Volvo, speeding to her home in San Anselmo. They got her computer, wrapped it in blankets, and placed it carefully in the backseat. Then they drove in the slow lane all the way back to the office, where the machine was, as Oren describes it, “carried into Pixar like an Egyptian pharaoh.” Thanks to Galyn’s files, Woody was back—along with the rest of the movie.

To understand this first event, you need to know that we rely on Unix and Linux machines to store the thousands of computer files that comprise all the shots of any given film. And on those machines, there is a command—/bin/rm -r -f *—that removes everything on the file system as fast as it can. Hearing that, you can probably anticipate what’s coming: Somehow, by accident, someone used this command on the drives where the Toy Story 2 files were kept. Not just some of the files, either. All of the data that made up the pictures, from objects to backgrounds, from lighting to shading, was dumped out of the system. First, Woody’s hat disappeared. Then his boots. Then he disappeared entirely. One by one, the other characters began to vanish, too: Buzz, Mr. Potato Head, Hamm, Rex. Whole sequences—poof!—were deleted from the drive.

need to download and install Python, get the recent most stable version from python.org and install it on your computer. If you already have Python installed on your Linux computer, do not uninstall the older 2.x as this may break your operating system. Instead, install the latest version alongside it. You may be required to use the command python3 and not python to initialize the interpreter though. All the information you need is provided on the documentation page of the Python.org website. We recommend you take the time to read the ‘Beginners Guide’ if you are still new to Python. Practical hacking: Free online hacking practice servers There is a saying in the world of information security that the best defense is a good offense. This is what has inspired many cyber security companies to make available deliberately vulnerable websites and servers to encourage developers, auditors, pentesters, system admins, and security professionals to practice their hacking skills online.

That's great, but what book should I read next?  What book would be a great companion

When you use the Linux command line, you are almost certainly using a program called the bash shell.

The shell is nothing more than a program that accepts your commands and executes those commands. Said another way, the shell is a command line interpreter.

Convert Text Files from Windows Format to Linux Format and Vice-Versa $ dos2unix $ unix2dos Sooner or later you're going to be sent a file or download one that uses a pair of CR (carriage return) and LF (line feed) characters to terminate lines in the file.  Those type of files are Windows/DOS formatted.  Unix-like operating systems simply use the LF character to terminate a line.  Sometimes this can cause issues.  To convert the file to a unix-like format, use dos2unix.  To examine the line termination characters use "cat -A" or the "file" command. $

Unlike Linux or Mac OS X, the Windows Command Prompt is not case sensitive, and does not distinguish between commands or filenames based up the case of the letters in the file name. To return to the previous example, the Command Prompt will interpret COPY, Copy, and copy as the same thing - every one of these will launch the copy command. In the same vein, Command Prompt will view Report.doc, REPORT.doc, and report.doc as the same file

Tab – It shows the completion possibilities for commands or filenames. Ctrl + A – This moves the cursor to the start of the current command line. Ctrl + C – This ends an active computer program and shows the prompt. Ctrl + D – This will log you out of the current session. This key combination is similar to typing logout or exit. Ctrl + E – It moves the cursor to the end of the current command line. Ctrl + H – This is similar to pressing the backspace key on your keyboard. Ctrl + L – This clears the current terminal. Ctrl + R – This searches the command history. Ctrl + Z – This allows you to suspend computer programs.

first of which would threaten the future of Pixar. To understand this first event, you need to know that we rely on Unix and Linux machines to store the thousands of computer files that comprise all the shots of any given film. And on those machines, there is a command—/bin/rm -r -f *—that removes everything on the file system as fast as it can. Hearing that, you can probably anticipate what’s coming: Somehow, by accident, someone used this command on the drives where the Toy Story 2 files were kept. Not just some of the files, either. All of the data that made up the pictures, from objects to backgrounds, from lighting to shading, was dumped out of the system. First, Woody’s hat disappeared. Then his boots. Then he disappeared entirely. One by one, the other characters began to vanish, too: Buzz, Mr. Potato Head, Hamm, Rex. Whole sequences—poof!—were deleted from the drive.

[    1.948637] usbcore: registered new interface driver hub   [    1.948795] usbcore: registered new device driver usb You can combine pipes together. For example, you get the exact same output by using head and displaying only the first three lines of the grep output: root@beaglebone:/tmp# dmesg |grep ‐i usb |head ‐n3   [    1.948582] usbcore: registered new interface driver usbfs   [    1.948637] usbcore: registered new interface driver hub   [    1.948795] usbcore: registered new device driver usb xargs: This is a very powerful filter command that enables you to construct an argument list that you use to call another command or tool. In the following example, a text file args.txt that contains three strings is used to create three new files. The output of cat is piped to xargs, where it passes the three strings as arguments to the touch command, creating three new files a.txt,

You can use rm -rf dir to delete a directory and its contents, but be careful! This is one of the few commands that can do serious damage, especially if you run it as the superuser. The -r option specifies recursive delete to repeatedly delete everything inside dir, and -f forces the delete operation. Don’t use the -rf flags with globs such as a star (*). And above all, always double-check your command before you run it.

there are some problems no Unix command can address.

1.1M    ./scripts 58M     ./cloud9 74M     . You can also use tee to write the output to several files at the same time, as shown in this example: root@beaglebone:/opt# du ‐d1 ‐h | tee /tmp/1.txt /tmp/2.txt /tmp/3.txt Filter Commands (from sort to xargs) There are filtering commands, each of which provides a useful function: sort: This command has several options, including (‐r) sorts in reverse; (‐f) ignores case; (‐d) uses dictionary sorting, ignoring punctuation; (‐n) numeric sort; (‐b) ignores blank space; (‐i) ignores control characters; (‐u) displays duplicate lines only once; and (‐m) merges multiple inputs into a single output. wc (word count): This can be used to calculate the number of words, lines, or characters in a stream. For example: root@beaglebone:/tmp# wc < animals.txt  4  4 18 This has returned that there are 4 lines, 4 words, and 18 characters. You can select the values independently by using (‐l) for line count; (‐w) for word count; (‐m) for character count; and (‐c) for the byte count (which would also be 18 in this case). head: Displays the first lines of the input. This is useful if you have a very long file or stream of information and you want to examine only the first few lines. By default it will display the first 10 lines. You can specify the number of lines using the ‐n option. For example, to get the first five lines of output of the dmesg command (display message or driver message), which displays the message buffer of the kernel, you can use the following: root@beaglebone:/tmp# dmesg | head ‐n5   [    0.000000] Booting Linux on physical CPU 0x0   [    0.000000] Initializing cgroup subsys cpuset   [    0.000000] Initializing cgroup subsys cpu   [    0.000000] Initializing cgroup subsys cpuacct   [    0.000000] Linux version 3.13.4-bone5(root@imx6q-sabrelite-1gb-0) tail: This is just like head except that it displays the last lines of a file or stream. Using it in combination with dmesg provides useful output, as shown here: root@beaglebone:/tmp# dmesg | tail ‐n2   [   36.123251] libphy: 4a101000.mdio:00 - Link is Up - 100/Full   [   36.123421] IPv6:ADDRCONF(NETDEV_CHANGE): eth0:link becomes ready grep: A very powerful filter command that can parse lines using text and regular expressions. You can use this command to filter output with options, including (‐i) ignore case; (‐m 5) stop after five matches; (‐q) silent, will exit with return status 0 if any matches are found; (‐e) specify a pattern; (‐c) print a count of matches; (‐o) print only the matching text; and (‐l) list the filename of the file containing the match. For example, the following examines the dmesg output for the first three occurrences of the string “usb,” using ‐i to ignore case: root@beaglebone:/tmp# dmesg |grep ‐i ‐m3 usb   [    1.948582] usbcore: registered new interface driver usbfs   [    1.948637] usbcore: registered new interface driver hub   [    1.948795] usbcore: registered new device driver usb You can combine pipes together. For example, you get the exact same output by using head and displaying only the first three lines of the grep output: root@beaglebone:/tmp# dmesg |grep ‐i usb |head ‐n3   [    1.948582] usbcore: registered new interface driver usbfs   [    1.948637] usbcore: registered new interface driver hub   [    1.948795] usbcore: registered new device driver usb xargs: This is a very powerful filter command that enables you to construct an argument list that you use to call another command or tool. In the following example, a text file args.txt that contains three strings is used to create three new files. The output of cat is piped to xargs, where it passes the three strings as arguments to the touch command, creating three new files a.txt, b.txt,

Linux – the sh shell, the zsh shell, the c shell, and others.

found on other Unix-like systems. The design is actually specified in a published standard called the Linux Filesystem Hierarchy Standard.

To see an input stream at work, enter cat (with no filenames) and press ENTER. This time, you won’t get your shell prompt back because cat is still running. Now type anything and press ENTER at the end of each line. The cat command repeats any line that you type. Once you’re sufficiently bored, press CTRL-D on an empty line to terminate cat and return to the shell prompt.

Linux Command Shell For Beginners

Yes, the success of open source does call into some question the utility of command-and-control systems, of secrecy, of centralization, and of certain kinds of intellectual property. It would be almost disingenuous not to admit that it suggests (or at least harmonizes well with) a broadly libertarian view of the proper relationship between individuals and institutions.

In trying to understand the Linux phenomenon, then, we have to look not to a single innovator but to a sort of bizarre Trinity: Linus Torvalds, Richard Stallman, and Bill Gates. Take away any of these three and Linux would not exist.

Strip out Comments and Blank Lines $ grep -E -v "^#|^$" file

This means that there were two major influences from Unix to Linux—GNU, which remains a prominent component of many different distributions of Linux, and the initial development of Linux done within the MINIX system.

Files by Date with Ease $ alias d='date +%F' By using the date format

However, universities could not modify UNIX to suit their individual needs. AT&T retained rights to the source code, which prohibited any alteration of

The history of Linux is long and complex, but we can provide a quick overview here. During the late 1960s and 1970s, AT&T's Bell Labs developed the UNIX operating system. UNIX was a powerful operating system, and universities across the United States soon used it in their computer labs.

book is part of the LinuxCommand.org project, a site for Linux education and advocacy devoted to helping users of legacy operating systems migrate into the future. You may contact the LinuxCommand.org project at http://linuxcommand.org.

strongest reasons early adopters of Linux chose it over, say, Windows NT was the powerful command line interface which made the “difficult tasks possible.” What This Book Is About This book is a broad overview of “living” on the Linux command line. Unlike some books that concentrate on just a single program, such as the shell program, bash, this book will try to convey how to get along with the command line interface in a larger sense. How does it all work? What can it do? What's the best way to use it? This is not a book about Linux system administration. While any serious discussion of the command line will invariably lead to system administration topics, this book only touches on a few administration issues. It will, however, prepare the reader for additional study by providing a solid foundation in the use of the command line, an essential tool for any serious system administration task. This book is very Linux-centric. Many other books try to broaden their appeal by including other platforms such as generic Unix and OS X. In doing so, they “water down” their content to feature only general topics. This book, on the other hand, only covers contemporary Linux distributions. Ninety-five percent of the content is useful for users of other Unix-like systems, but this book is highly

You can use rm -rf dir to delete a directory and its contents, but be careful! This is one of the few commands that can do serious damage, especially if you run it as the superuser. The -r option specifies recursive delete to repeatedly delete everything inside dir, and -f forces the delete operation.

For a new Linux user I recommend using a popular Linux distribution such a Linux Mint or Ubuntu from the Debian family, or Fedora.  These distributions tend to have the latest technology and are very easy to use.  I also recommend learning how to use both a Debian variant and Fedora variant as there a some major differences between the variants and knowing how to use both will improve your Linux skills and marketability in the job market.  You will need