=====================================
Unix Workout: Unix Pipelines and More					[TOC]
=====================================

By now you already have some experience with the Unix shell. So some of the
material covered in the following three tutorial will not be new to you:

- __Tutorial 1__: Listing files and directories. Making and changing
  directories.
- __Tutorial 2__: Copying, moving and deleting files. Displaying the
  contents of a file on the screen
- __Tutorial 3__: Redirecting output and using pipelines.

Read through these tutorial and _learn by doing_ what is new. For example, the
`grep` command in __Tutorial 2__ and Unix pipelines in __Tutorial 3__. In the
following entertaining video __Brian Kernighan__ (one of the original Unix
inventors) talks about the `grep` command:


---- VIDEO ------------------------------
https://www.youtube.com/embed/NTfOnGZUZDk
-----------------------------------------

Quiz
====
From the tutorial you know that

---- CODE ----------------------------------
grep foo some_file.txt
--------------------------------------------

prints all lines of `some_file.txt` that contain the string `foo`. But actually
the `grep` command is much more powerful! You also can print out all lines that
match a so called __regular expression__. For example

---- CODE ----------------------------------
grep "^[a-zA-Z]*(" some_file.txt
--------------------------------------------

prints all lines that begin with a word that is followed by an open
parenthesis. Hereby the word is described as follows:

- It only has characters `a` to `z` or `A` to `Z` and
- it can have zero or arbitrary many characters.

---- BOX -----------------------------------------------------------------------
Extract from the file `/home/numerik/pub/ss22/session03/lexer.c` on `theon`
all the lines that begin with a word as described above. Sort these lines
alphabetically and save this sorted list in a file `list.txt`. Of course this
can be done with a one-line command.  Write this command into a file `cmd.txt`

submit hpc quiz03 list.txt cmd.txt

--------------------------------------------------------------------------------




:links: Tutorial 1 -> http://www.ee.surrey.ac.uk/Teaching/Unix/unix1.html
        Tutorial 2 -> http://www.ee.surrey.ac.uk/Teaching/Unix/unix2.html
        Tutorial 3 -> http://www.ee.surrey.ac.uk/Teaching/Unix/unix3.html
	Brian Kernighan -> https://en.wikipedia.org/wiki/Brian_Kernighan
	regular expression -> https://en.wikipedia.org/wiki/Regular_expression