Part 1 : What is the terminal?

Terminal/Shell

Open a terminal.

• When you type something into the command line, a program called “the shell” interprets it and does something.
• So, there are a couple of things that are required for the shell to correctly interpret what you want to happen…
  • All command line entries start with a command name, followed by options and arguments.
  • Some commands don’t need any options or arguments.
  • The command name, options, and arguments are separated by spaces.

Demo - First Commands

demos/02-first.sh

Tab Completion and Command History

demos/02-tab_and_history.sh

Part 2 : Where are my files?

Navigating

• Your computer has a set of files organized into directories.
• Example:
  • Open a file browser
  • Open a terminal

Commands:

• pwd - print the directory you are currently in
• ls - list the files and directories that are in the current directory
• cd - change directories

Demo - Navigation

demos/03-navigation.sh

Command Arguments and Options

• Commands can take arguments.
• The command does something with/to the argument
  • Examples:
    • cd Desktop
    • ls Desktop
• Options change the behavior of a command.
  • Examples:
    • ls -l
    • ls -l -a
• So, when you type in a command you are telling the shell:
  • What you want to do (the command)
  • What you want to do it to (the argument(s))
  • How you want it done (the option(s))

Creating and Deleting Files and Directories

Commands:

• mkdir - make a new directory
• cp - copy a file or directory
• mv - move a file or directory
• rm - remove a file or directory

Demo - Creating and Deleting Files and Directories

demos/04-createdelete.sh

Absolute and Relative Paths

• pwd print the “absolute path” of the current directory (the directory you are in).
• In Linux (and other Unix-like operating systems), all directories are a sub-directory of a single directory named /.
  • We call this the “root” directory.
• Each user on the system gets their own directory to store files.
  • We call this user’s “home” directory
• Absolute paths give the location of a directory or file from the root directory
  • Example: /home/cclark/Desktop
• Relative paths give the location of a directory or file from the current directory
  • There are two special directory names:
    • ./ is the current directory.
    • ../ is the parent directory (the directory above the current directory).
  • Example: ./Desktop (from my home directory)
  • Example: ../ (from my home directory)
• Any command that takes a filename as an argument will accept absolute or relative path names.

Demo - Absolute and Relative Paths

demos/04-rel_abs_paths.sh

Part 3 : Sandboxes

Sandboxes

• Download and unpack the sandbox for today from the website.
• Sandboxes are stored in an archive file (like zip files), that most people car a “tarball”.
• The tar command is used to “untar” the tarball.
  • Required Options:
    • -x extract archive
    • -j tarball has been compressed using bzip2
    • -f the name of the archive file
  • tar -x -j -f Module-01-Sandbox.tar.bz2
  • Shorthands (tar specific!)
    • tar -xjf Module-01-Sandbox.tar.bz2
    • tar xjf Module-01-Sandbox.tar.bz2
  • This will not work: tar xfj Module-01-Sandbox.tar.bz2

Demo - Sandboxes

demos/05-sandboxes.sh

Practice

Download the sandbox for this module and perform the following task:

1. How many directories are in the sandbox directory?
2. How many files are in the sandbox directory?
3. Go into the directory named data/
   1. Delete the file named run03.txt
   2. Determine how many files are in the directory named old/, without going into the directory.
   3. Delete the directory named old/
4. Go back to the top directory in the sandbox.
5. The directory named config/ contains a subdirectory named resources/. Go into this directory.
   1. Use ls -l to list the files and directories in the top level of the sandbox from this directory.
   2. The directory named config/ (in the top level of the sandbox) also contains a subdirectory named physical_quantities/, which contains a file named constants.txt. Delete this file without changing directories.
   3. The directory named config/ (in the top level of the sandbox) also contains a subdirectory named tmp/. Delete this directory without changing directories.

Part 4 : Working with many files at once

Globs/Wildcards and Expansion

The shell provides some useful features for generating argument lists.

Wildcards

• The shell understands some “wildcard” or “glob” patterns.
• * matches anything 0 or more times
  • Examples:
    • rm *.txt will remove all files that end with .txt
    • rm data-*.txt will remove all files that begin with data- and end with .txt
    • rm */*.log will remove all files that end with .log and are in a subdirectory of the current directory.
• ? matches anything 0 or 1 time
  • Examples:
    • rm data-0?.txt will remove data-01.txt, but not data-011.txt

Expansion

• file-{x,y}.txt expands to file-x.txt file-y.txt
  • Examples:
    • mkdir dir0{1,2,3} will create three directories named dir01/, dir02/, and dir03/.

These are provided by the shell, so they will work for all commands.

Demo - Wildcards and Expansions

demos/07-wildcards.sh

Part 5 : Spaces…

Spaces

• Spaces in file or directory names cause a problem because the shell uses spaces to separate the command name, command options, and command arguments.
• If you try to remove a file named Report 1.pdf with rm Report 1.pdf, the rm command will try to remove two files, one named Report, and one named 1.pdf.
• There are two ways to fix this:
  • Put quotes around the name: rm "Report 1.pdf"
  • Escape the space (put a rm Report\ 1.pdf in front of it)
• Wildcards are also helpful: rm Report*1.pdf will work (So would rm R*.pdf).

Demo - Spaces

demos/09-spaces.sh

The End

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