Read the `man vim` entry for more details. Instead different keys do specific commands like delete whole words or lines. Unlike `nano` it's default mode is not as a direct editor. `vim` is an old-school Linux text editor. ![]() It works in a separate screen, where you can move the cursor with arrow keys, add new text, or type over old text, loosely similar to Word. `nano` is a user-friendly interactive text editor for Linux. Linux has several tools for file editing. Often however, that will be impossible because of the file's size. Sometimes the easiest way to edit a file will be to copy it from **nscc** to your computer and then copy it back. The example below will show only lines from `history` that have a two-letter word beginning with 'l', flanked by spaces. Refer to chapters 2-3 of () for more details on regex. This will filter the output of `history` showing only the lines where you used the `cd` command (or where the characters "cd" occurred). To search based on one in Linux, use the command `grep`. It's often useful to search the contents of files of the output of other programs for particular sequences of characters. We'll see an example in the next section. If you want to send the output of one program to another program use the "pipe" character `|`. If you want to add new output to the end of an existing file use `>` For example, `ls > filenames.txt` will create a new file with the output from `ls`. The greater than sign `>` redirects the output of a program to a new file. You can redirect that output using a few special characters. The output generated by all the programs in Linux go to "stdout", the screen. You can also search backward in the file with `?`. When you're in `less`, you can also search forward by hitting `/` and entering your search string, then hitting enter. `less` opens a program where you can view the entire contents of a file, one page at a time. If the file is actively being added to by a program, you can have `tail` continuously write out the contents as they're added in with `tail -F` If you want a number other than 10, for example 4, use `head -n 4` `head` shows the first 10 lines of a file. `cat` displays the entire contents of a file to the screen. Linux provides lots of way to examine the contents of files, which is excellent for big data. Scp test.txt this example `test.txt` will copied to your homer folder on **nscc**. Other characters like the greater than `>` and less than ` test.txt ![]() These are denoted after the program's name by one or two dashes, `-`. The function of a program can be modified by "parameters" (also called "switches" or "arguments"). To run a program (or "command"), enter its name in the command line. Question marks for one character asterisks for any number of contiguous characters. Question marks and the asterisks (`*`) are "wild cards" and are meant to stand in for any character. If a file has been imported into a Linux system from Windows or Mac OSX spaces are "escaped", meaning they can only be referenced by preceding them with the back-slash `\`. So you can't use a space character in a file name. Spaces separate commands, parameters and filenames. ![]() More importantly, certain characters have special meaning in the bash command line, and you'll need to learn to treat them carefully. You can share notes, instantly publish to the web, or keep things private. It's cloud-based, but you can download files or back-up to Google Drive or DropBox. () is my preferred markdown editor at the moment. () is a web app or () that provides a similar split-screen editor for cloud-based markdown note keeping. () runs on your computer and renders your Markdown code in real time in a split screen. However, you may want to use an editor that is specialize for Markdown. You can write Markdown easily in any plain text editor. In this way, your entire workflow, from bash to R, can be recorded in one simple document. Most of our workflows will end up in () where Markdown code can seemlessly become () code. The major advantage to Markdown over something like Google Docs is that it is fundamentally just text, and it can be easily moved to new platforms. I recommend taking notes in (), a simple way to annotate your notes in a text document. There are lots of ways you could do this, including using a paper notebook, Word, Google Docs, or a text editor. Note taking is important! Just like you'd keep a lab notebook at the bench, if you're working at the terminal, you should keep detailed records of what you've done and explanatory notes to yourself. There are some small differences in syntax compared to other shells, such as tsch. You can think or it as a local dialect of Linux. For other resources, check out ().īash is a Unix or Linux shell. This is a lesson plan to teach basic commands to new users of the bash command line.
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