💻 Command-Line Cheat Sheet

The DSMLP servers use Linux. As such, when interacting with them, all of the command-line commands you use should be Linux-specific (which, for the most part, also work on macOS). Many of the key commands you’ll need to know are summarized below.

Basics

Command	Description	Example
`man`	Shows the `man`ual for a command. This can be helpful for seeing how to run a command or what flags (parameters) a command takes.	`man cp` shows the manual for the `cp` (copy) command.
`pwd`	Displays your `p`resent `w`orking `d`irectory.	`pwd`, when run immediately after opening my Terminal, shows `/Users/surajrampure`.
`ls`	`l`i`s`ts all files in the current directory.	`ls` `ls -a` (also shows all of the hidden files and folders in the current directory (like `.gitignore`))
`mkdir`	`m`a`k`es a new `dir`ectory (folder) with the name you specify.	`mkdir hello` creates a folder in your present working directory named `hello`. Verify this using `ls`.
`cd`	`c`hanges your current `d`irectory to be the one specified.	`cd hello` enters the directory `hello`, if it exists in the present working directory. `cd` by itself always returns you to your “home” directory.
`touch`	Creates an empty file with the specified name.	`touch ucsd.txt` creates a file named `ucsd.txt` in the present working directory.
`cat`	Shows the contents of a file.	`cat hello.txt` will display all of `hello.txt`.
`mv`	`m`o`v`es a file to a specified location.	`mv ucsd.txt ../hello.txt` moves a file from the present working directory to the parent directory. Note: In Linux, `.` represents the current directory and `..` represents the parent directory.
`cp`	`c`o`p`ies a file from one location to another.	`cp hello.txt ../hey.txt` makes a copy of the contents in the file `hello.txt` and saves it in the file `hey.txt`, stored in the parent directory of the present working directory. Note: To copy a folder, use the `-r` flag, which stands for “recursive.”

To verify that you’ve synthesized the above information, answer the following questions:

What does cd .. do?
What does ls ../hello do?

File Editing

Command	Description	Example
`vim`	A command line-based text editor.	`vim hello.txt` opens `hello.txt` in `vim`.
`emacs`	Another command line-based text editor.	`emacs hello.txt` opens `hello.txt` in `emacs`.

Servers and Networks

Command	Description	Example
`ssh`	Used to access servers (amongst other things).	`ssh srampure@dsmlp-login.ucsd.edu` is how Suraj accesses DSMLP.
`scp` / `sftp`	Allows you to move files between your local machine and a remote server (essentially `ssh` + `cp`).	`scp dog.txt srampure@dsmlp-login.ucsd.edu:test.txt` copies the file `dog.txt` from your local machine to Suraj’s DSMLP drive (replace with your own username). See DSMLP documentation for more.
`wget`	Downloads the contents of a webpage.	`wget https://raw.githubusercontent.com/ericmichael/cooltxt/master/cool.txt` creates a new file called `cool.txt` with the contents of the aforementioned URL.

Other

Command	Description
`clear` or `ctrl + l`	Clears the Terminal window.
`history`	Shows the commands you’ve entered in the past.
`ctrl + r`	Allows you to search your command history to easily find a command you entered in the past.
`screen`	Allows you to run tasks in the background. See here for more details.
`git`	See usage reference here.
`grep`	Helps you quickly search text (both individual documents and folders). The general pattern is `grep -inr <keyword> <file_path>`. For example, `grep -inr dog hello.txt` will display all lines in which `'dog'` occurred in `hello.txt`.
`find`	Helps you quickly find a file using regex. For example, `find <path> -iname <regex>`.
`htop`	Shows you all of the processes currently running on your server and the amount of resources (e.g. CPU and memory) that you’re using.

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