EECS 484 Projects | tools

Tools

This spec is archived and not for the current semester.

This document houses the tools necessary to succeed in EECS 484. You will explore most of these in Project 1 (before starting Part 2), and you can refer back to this document as a refresher for Projects 2 and 3.

CAEN

To connect to CAEN remotely and to use SQL*Plus, you will need to

sync your files between your local machine (to submit to the Autograder) and a CAEN machine (for SQL*Plus testing), and
ssh into a CAEN Linux machine to run your files

Many of you have visited the tutorial at EECS 280 Setup Tutorial. You are free to use any setup that has worked in the past for you, but remember that running your scripts on CAEN will produce more helpful error descriptions than the ones provided by the Autograder. We’ve summarized the most common options below.

It is your responsibility to ensure you have access well before any deadlines. It may take staff several hours or days to help debug machine-specific workflows. For this reason, we recommend starting with the most familiar approach (command line ssh and git) before trying out rsync, Visual Studio Code, or other options.

Option 1 (Terminal)

The first option is to do all your development on your local machine, but periodically copy your files to CAEN for testing through the terminal.

You can use git version control (see EECS 485 Git Tutorial), which has the benefit of keeping track of your files over time.
For a faster approach, you can copy your local files to CAEN with the rsync command (omit angle brackets).

$ rsync -rtv <local_folder> <uniqname>@login.engin.umich.edu:<remote_folder>

Now that your files are on CAEN, to ssh into it, run

$ ssh <uniqname>@login.engin.umich.edu

Pro tip: If you wish to copy your files from CAEN to your local machine, you can switch the source and destination paths.

Option 2 (Visual Studio Code)

The second option is to utilize Visual Studio Code’s ssh extension to do your development on a CAEN machine and periodically sync your files back to your local machine with Git/rsync. This might be a better option if you want to test your scripts frequently without having to sync often. It can, however, take longer to debug machine-specific issues.

First, in Visual Studio Code, download the Remote - SSH extension. Open Command Palette, select the option Remote-SSH: Open SSH Configuration File…, and select the first configuration file in the list. For MacOS users, this should open the ~/.ssh/config file.

Add the following to the bottom of the file (omit angle brackets):

# CAEN
Host caen
    Hostname login.engin.umich.edu
    User <uniqname>
    ControlPersist 1h

Next, under the extension settings for Remote - SSH, check the option to Lockfiles in Tmp.

Open Command Palette, select the option Connect Current Window to Host… and choose caen. After entering your CAEN password and Duo authorization, you should now be able to edit your files directly on CAEN with Visual Studio Code as a text editor.

Pro tip: If you were able to successfully connect to CAEN once, but it fails the next time you try to connect, try killing the connection first and waiting for the log notification to confirm that it was killed. To do so, open Command Palette and select the option Remote - SSH: Kill VS Code Server on Host. Alternatively, ssh into CAEN and remove the .vscode directory with rm -rf .vscode.

Windows Users

For Windows users, we recommend using WSL as shown on the EECS 280 website and following the same steps as Linux/MacOS users. You can, however, use tools like PuTTY, WinSCP, or Cyberduck to ssh into CAEN and sync your files.

Class Modules

On CAEN, in order to use SQL*Plus (Projects 1-3), you will need to load the class module by running module load eecs484 every time you open a new terminal session. If you forget to load the module, you will encounter the error ORA-12162: TNS:net service name is incorrectly specified when you login to SQL*Plus.

On CAEN, in order to use the mongo shell (Project 3), you will need to load the mongoDB module by running module load mongodb every time you open a new terminal session.

Pro tip: To automatically load all modules every time you login, run the following on CAEN. You only need to do this once at the beginning of the semester.

$ echo "module load eecs484" >> ~/.bash_profile
$ echo "module load mongodb" >> ~/.bash_profile

For Project 1 (accessing the public data set and testing scripts) and Project 2-3 (viewing database tables), you will be using a command line interface (CLI) from Oracle called SQL*Plus.

A SQL*Plus account has already been set up for you by the staff. To access your SQL*Plus account, you must be on a CAEN Linux machine (see CAEN). To start SQL*Plus, run

$ rlwrap sqlplus

Your username is your University of Michigan uniqname, and your password is eecsclass (case-sensitive). The first time you log in, the system will prompt you to change your password, which we recommend you do.

Only use alphabetic characters, numerals, the underscore, and the pound sign in your SQL*Plus password. Never use quotation marks, the ‘@’ symbol, or the ‘$’ symbol in your SQL*Plus password. If you do, it is likely that you will not be able to log into your account, and you will need to reset it (see Resetting Password and Sessions).

If you encounter the error ORA-01017: invalid username/password; logon denied, then you may not have an account. Please privately post on Piazza with your uniqname to request access.

Resetting Password and Sessions

We have made an Autograder project named SQL*Plus Reset that would allow you to reset your SQL*Plus password or kill your SQL*Plus sessions.

To reset your password to eecsclass, submit any text file named password.txt to this project.

To kill all your SQL*Plus sessions and fix the ORA-00054: resource busy and acquire with NOWAIT specified or timeout expired error, submit any text file named sessions.txt to this project.

If you still have issues accessing your SQL*Plus account after trying the solutions above, please privately post on Piazza with your uniqname and we can take a look. Keep in mind that this may take several hours, during which you will be unable to use SQL*Plus to work on the project.

Helpful SQL*Plus Commands

Once in SQL*Plus, you can execute arbitrary SQL commands. You will notice that the formatting of output from SQL*Plus can be less than ideal. Here are some commands to access metadata and make the output more readable.

Remember that SQL commands are case-insensitive but must end in a semicolon. SQL*Plus (not SQL) commands like DESC and @createTables do not need to end in a semicolon. SQL*Plus can also execute multi-line commands if you click the Enter key between lines (you will see line numbers show up). As always, omit angle brackets:

To view all of your tables, run:

SQL> SELECT table_name FROM user_tables;

To view all of your views, run:
```
SQL> SELECT view_name FROM user_views;
```

To view all of your sequences, run:

SQL> SELECT sequence_name FROM user_sequences;

To view all of your triggers, run:

SQL> SELECT trigger_name FROM user_triggers;

To view the full schema of any table, including the tables of the public dataset, run:
```
SQL> DESC <table name>;
```
To set the width for a character column to num chars, run:
```
SQL> COLUMN <column name> FORMAT A<num chars>;
```
To set the width for a number column to (for example) 3 digits, run:
```
SQL> COLUMN <column name> FORMAT 999;
```
To remove the formatting from a column, run:
```
SQL> COLUMN column_name CLEAR;
```
and to remove the formatting from all columns, run:
```
SQL> CLEAR COLUMNS;
```
To change the number of characters displayed on a single line from the default of 100, run:
```
SQL> SET LINE <num chars>;
```
To select on the first several rows from a table you can use the ROWNUM pseudocolumn, such as:
```
SQL> SELECT * FROM <table name> WHERE ROWNUM < <num>;
```
To load commands in SQL*Plus from a file, say createTables.sql, run the following. The name of the file is relative to the current directory from which sqlplus was launched:
```
SQL> @createTables.sql
```
or
```
SQL> @createTables
```
To quit SQL*Plus, press Ctrl+D or run:
```
SQL> QUIT
```

SQL*Plus Potholes

SQL*Plus is a raw command line tool that can be picky about the formatting of your scripts. Some common errors include:

Blank lines inside of a command will cancel the command.

SELECT *
FROM table_name;

SELECT *
     
FROM table_name;

Begin multiline comment symbol /* must have a space right afterwards.

SELECT * FROM table_name;
/* this is a good multiline
comment block*/

SELECT * FROM table_name;
/*this is a bad multiline
comment block*/

Comments should not come right after the semicolon.

SELECT * FROM table_name;
-- this is a good single line comment
SELECT * FROM table_name;
/* this is a good single line comment*/

SELECT * FROM table_name; -- this is a bad single line comment
SELECT * FROM table_name; /* this is a bad single line comment*/

Acknowledgements

This document was written and revised over the years by EECS 484 staff at the University of Michigan. The most recent version was updated and moved to Primer Spec by Owen Pang.

This document is licensed under a Creative Commons Attribution-NonCommercial 4.0 International License. You may share and adapt this document, but not for commercial purposes. You may not share source code included in this document.

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