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Using the Terminal

Using the Terminal

Goals: Introduction to using a Terminal

  • What does a prompt look like?

  • General syntax of shell command.

  • Commands/options are case sensitive.

  • Getting Help:

    • Man pages (man)

    • Options: <command> --help

Login

  1. Open up Chrome

  2. Navigate to: MedicineBow OnDemand

  3. Type in your provided username and password. Usually this will be your UWYO username and password, unless you are using an assigned training account.

  4. Authenticate using your preferred 2 factor method (expandable directions below):

If you usually get a two-factor push to your phone, just hit enter after entering your username and password, then complete authentication by approving the push on your device.

 

pushapprove.png

Without hitting enter after typing in your username and password, in the password text box, append a comma (,) to the end of your password, then append phone as shown in the screenshot below:

You should get a phone call on your main phone # associated with your two factor account. Answer this call and hit # to approve access.

If you prefer to use a 2 factor passcode from your Duo Mobile app, without hitting enter after typing in your username and password, in the password text box, append a comma (,) to the end of your password, then append the multi digit passcode found in duo mobile as shown in the screenshot below:

Type in the account password, then, without hitting enter, append a comma (,) to the end of the password, then touch the light on the yubikey as shown in the screenshot and photo below:

Then hit the green light on your yubikey to authenticate:

yubikey.jpeg

 

Start MedicineBow Shell Access

Click shell.png

 

 

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The Command-Line Prompt

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Your Prompt

From now on, your prompt will take the form: [<username>@<hostname> ~]$

where:

  • <username> is YOUR username or potentially arcc-txx if you are using a training account.

  • <hostname> will take the form of mblog1, mblog2 - it should have log within the name to indicate you are using a login node - this will be covered within the Intro to HPC workshop, specifically What is HPC?

Syntax of a Shell Command

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Linux IS Case Sensitive

In Linux, commands, options, folder, filenames… are Case Sensitive.

# Lists what is in the current location. [<username>@<hostname> ~]$ ls Desktop Documents Downloads # Throws an error. [<username>@<hostname> ~]$ LS -bash: LS: command not found Filename  ≠  FiLeNaMe  ≠  FILENAME

 Remember: Filename  ≠  FiLeNaMe  ≠  FILENAME

Getting Help: man

Linux has a number of ways to find help on commands. The first is man - “manual”.

[<username>@<hostname> ~]$ man ls LS(1) User Commands LS(1) NAME ls - list directory contents SYNOPSIS ls [OPTION]... [FILE]... DESCRIPTION List information about the FILEs (the current directory by default). Sort entries alpha‐ betically if none of -cftuvSUX nor --sort is specified. Mandatory arguments to long options are mandatory for short options too. -a, --all do not ignore entries starting with . -A, --almost-all do not list implied . and .. ... Manual page ls(1) line 1 (press h for help or q to quit)

Getting Help: <command --help>

The next method is to use a command's --help option.

[<username>@<hostname> ~]$ ls --help Usage: ls [OPTION]... [FILE]... List information about the FILEs (the current directory by default). Sort entries alphabetically if none of -cftuvSUX nor --sort is specified. Mandatory arguments to long options are mandatory for short options too. -a, --all do not ignore entries starting with . -A, --almost-all do not list implied . and .. --author with -l, print the author of each file -b, --escape print C-style escapes for nongraphic characters --block-size=SIZE with -l, scale sizes by SIZE when printing them; e.g., '--block-size=M'; see SIZE format below -B, --ignore-backups do not list implied entries ending with ~ ...

Getting Help: Options

Typically, options can have a:

  • short-name: “-a”:

    • Single letter following a single “-”

  • long-name: “--all”: 

    • More descriptive word after two dashes “--”

Short options can be grouped: 

  • “ls -a –l” can be shortened to “ls –al”

Single vs Multiple Lines

If you have a long command, which is difficult to read over a single line, you can split it up across multiple lines.

To split, at the end of the line where you want to split type \ followed by ENTER, and you’ll see that me move to the next line as indicated by the >.

You can continue to split across multiple lines.

Once you’re ready to execute, simply press ENTER (without the \ character).

[<username>@<hostname> ~]$ ls -al ~ [<username>@<hostname> ~]$ ls \ > -al \ > ~

Exercises

Questions:

  1. Is there a difference between running ls versus ls -al?

  2. How can you find out what the –al options do?

  3. What does the pwd command do?

  4. From the command line, what happens if you press the up/down arrow keys?

Answers(1)

1: Is there a difference between running ls versus ls -al?

Yes. The ls command is used to list files.

The characters after the '-' are flags, which select options associated with the command.

[<username>@<hostname> ~]$ ls Desktop Documents Downloads [<username>@<hostname> ~]$ ls -al total 76 drwxr-x--- 8 <username> <username> 4096 Oct 3 13:57 . drwxr-xr-x 925 root root 32768 Sep 27 16:21 .. -rw------- 1 <username> <username> 212 Sep 12 15:44 .bash_history -rw-r--r-- 1 <username> <username> 18 Aug 10 17:00 .bash_logout -rw-r--r-- 1 <username> <username> 141 Aug 10 17:00 .bash_profile -rw-r--r-- 1 <username> <username> 376 Aug 10 17:00 .bashrc drwx------ 3 <username> <username> 4096 Sep 12 11:36 .config drwxr-xr-x 2 <username> <username> 4096 Aug 10 17:00 Desktop drwxr-xr-x 2 <username> <username> 4096 Aug 10 17:00 Documents

Answers(2)

2: How would you find out what the –al options do?

  • Use man ls or ls --help

    • -a is to specify “all”, which will include hidden files.

    • -l is to specify “long” which gives us the “long format” output about the listed files.

  • Options are also case sensitive:

    [<username>@<hostname> ~]$ ls -A .bash_history  .bash_profile  .config  Documents  .emacs     .kshrc    .mozilla  .zshrc .bash_logout   .bashrc        Desktop  Downloads  .esd_auth  .lesshst  .ssh

Answers(3, 4)

3: What does the pwd command do?

  • Use man pwd or pwd --help

  • pwd - print name of current/working directory

4: From the command line, what happens if you press the up/down arrow keys?

Steps through the previous commands you’ve typed. What do you find?

This should access your previous commands. Hitting the up arrow once will give you the last command you typed in. Pressing it over again will produce the command that preceded that one, and so on.

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Intro to Linux CLI: The File System

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The Linux File System