linux:ssh

SSH

Welcome to the command line it is a wonderful place!

A command line (or terminal) window is a way to interact with a computer on a more basic level than a GUI. It allows for easier automation as it is much easier to repeat and automate text commands than commands that involve the mouse and GUIs.

Command line also allows for easy managment of remote servers that don't have the computational resources to display a visual interface.

Also using the mouse is slow!

Please open a terminal window and try these commands to give a better idea of how each work!

Every CLI (command line interface) window is looking at a folder (or directory) on your computer.

pwd - Print working directory, will return the current directory you are looking at. So if you are in your home folder in OS X it will return /User/<your-username>/.

ls - Tells you what files are folders are in your current directory.

Often command line commands have optional tags and arguments you can give them. There are two type of tags single letter and multi-letter. Single letter tags are formatted like this ls -l, a single dash and then a single letter. Multi-letter tags are formatted command –tag, two dashed and then a multi-letter tag.

ls has two commonly used single letter tags:

  • ls -a - Same format as ls, but includes hidden files.
  • ls -l - Outputs the current directory contents in a more verbose list format (Generally easier to read).

You can combine most single letter tags by just listing them one after the other with only a single dash before all of them e.g. ls -la which is a common command allowing you to see a lot of useful information about the current directory including it's hidden files.

cd - Change directory, will go to a relative or absolute path directory.

To go to a absolute directory include a leading slash like cd /etc/ will take you to the etc folder in the root of your drive. A relative path is one that starts with the name of a relative folder so cd Desktop will open up your desktop folder if the command line is currently in your home (in OSX, this is your username's folder).

A good directory shortcut is ~ which references your home directory so cd ~/Documents will take you to your Documents folder from anywhere. Another shortcut is using a .. as a placeholder to indicate you want to move up a folder. If you're in ~/Document/Work/Web and type cd .., you'll then be in ~/Document/Work.

In OS X you can drag a folder from the finder onto the command line to get it's path, so typing cd then dragging the folder would allow for an easy way to get to a specific folder without having to type out the whole thing. If you are using Mavericks you can also use this trick.

Many CLI commands allow for autocompletion cd included press tab after typing a few letters and the command prompt will attempt to fill it in so typing cd ~/Doc then tab will autocomplete out to cd ~/Documents/ you can repeat this to drill down into folders as well.

So you've gotten to an awesome folder or file but now you're scared and you need the GUI back.

The open command in OS X allows you to open a file or folder like you would if you double CLI on it, so if you run it on a folder it will open finder at that location. If you run it on a file it will open the default program for that file type!

open doesn't work in non OS X operating systems or may have alternate functionality.

touch <filename> - This creates a blank file named and located in the first argument. To create file in a sub directory, touch <sub-dir>/<filename>.

rm <filename> - Remove the specified file. Two commonly use options are the, -r option which allows you to remove folders, and the -f option which forces the remove command to remove files that it would normally ask to confirm deletion. Be carefull! The rm command skips the trash can so you can't recover files removed this way.

rm -R <foldername> - Delete folder, any files it contains, any sub-folders it contains, and any files or folders in those sub-folders, all the way down. This deletion is final.

rm -iR <foldername> - Confirm the deletion of each item.

mv <filename> <sub-dir>/<filename> - Moves a file to a new location, so in our case, moves the <filename> file to the <sub-dir> sub directory. The first argument is the actual path/name of the file to be moved, and the second argument is the desired destination path/name. This also works to rename a file: mv <filename> <new-filename>.

cp <filename> <directory> - Copy <filename> to <directory> (possibly overwriting an existing file).

cp -r <directory1> <directory2> - Copy and its contents to (possibly overwriting files in an existing directory).

mkdir <new-folder> - Makes a directory (folder) in the specified path/name. To make a new folder in a sub-folder, the same rules apply: mkdir <sub-dir>/<new-folder>.

cat <filename> - Output the contents of <filename> in the command line.

defaults write com.apple.finder AppleShowAllFiles TRUE - Show Mac OS X system files that start with a dot (ex: .htaccess). Hide the system files by executing the same command, but set TRUE to FALSE. Enter killall Finder to refresh the Finder.

su <username> - Switch Username.

You can switch users in the command line. Say you need to get a file in Sally's home directory but you're logged in as osx-user. You can switch users with su sally, you'll have to know her password, of course. You can su to temporarily take on the identity of another user. Sometimes all that user switching gets confusing, in case you forget you can always find out who you are by typing whoami. If you used su to switch into another user's account, you can use exit to switch back to your original account.

One big advantage of the command line is the ability to manage remote servers easily. Most web servers do not have a visual desktop to access, and while many have built in control panels, you can have greater control by connecting to them through the command line.

There are several distrobutions of Linux, this cheat-sheet will focus on Ubuntu.

ssh (secure shell) allows you to connect to a remote server using the command line. The standard usage is ssh username@server-address.net where username is your username on the remote server amd server-address.net is the URL or IP of the remove server.

SSH has many powerful features, such as unique keys per remote server you connect to (more secure) and the ability to set default configuration on a per server basis. Read the SSH Management page to learn how to take full control over your SSH connections.

sudo apt-get update

or

sudo apt-get update && sudo apt-get upgrade

This command will install the entire stack: sudo apt-get install lamp-server^

Or you can install them one-by-one:

Apache sudo apt-get install apache2 libapache2-mod-php5

rather use NGINX?

NGINX sudo apt-get install nginx MySQL sudo apt-get install php mysql-server mysql-client PHP sudo apt-get install php5 php5-gd php5-mysql php5-curl php5-cli php5-cgi php5-dev php5-fpm phpMyAdmin sudo apt-get install phpmyadmin
  • linux/ssh.txt
  • Last modified: 2017/06/02 21:42
  • by 23.122.147.117