add scripting_exercises

linux_intermediate/index.rst

@@ -15,6 +15,8 @@ Intermediate Linux Course: Commandline and Basic Scripting
    Commandline Exercises <exercises>
    Basic Scripting <basic_scripting>
    Solutions <solutions>
+   Scripting Exercises <scripting_exercises>
+
    appendix
 
 ..   I/O Redirection <redirection>

linux_intermediate/scripting_exercises.rst

+Propositions for Scripting Exercises
+====================================
+
+Here are some ideas (not elaborated propositions) for some useful scripts which you might want to implement. 
+Extend them to your liking.  
+Thanks to Grischa Toedt & Chrysoula Pantzartzi for the ideas.
+
+General "Unpacker"
+------------------
+
+Purpose:
+    Unpack a file or a number of files according to their packing or
+    compression format (tar, gzip, zip, bzip, xz, see
+    http://en.wikipedia.org/wiki/List_of_archive_formats for more ideas).  This
+    script can be used as a general wrapper around the various compression and
+    packing tools with an uniform set of options
+
+**Usage Example**::
+
+    $ ls -F
+    archive.tar.gz    text.txt    zuppfile
+    $ unpack *
+    archive.tar.gz is a gzip compressed tarfile ... uncompressed and unpacked
+    text.txt is not compressed or packed ... skipping
+    zuppfile is a zip compressed archive ... uncompressed and unpacked
+    $
+
+Required tools and commands:
+    :index:`file`, :index:`tar`, :index:`gzip`/:index:`gunzip`, :index:`zip`/:index:`unzip`, :index:`bzip2`/:index:`bunzip2`, :index:`xz`, etc.
+
+Things to consider: 
+ * The type of a file is not necessarily deductible from its extension
+ * What if the file doesn’t have an extension at all?
+ * Depending on the tool and how the file has been archived, the unpacking/uncompressing can result in files 
+   being created in a subdirectory or directly in the current working directory. Is this what one wants/expects?
+ * What if the destination directory already exists?
+ * Some tools preserve the original archive, others don’t
+
+Extendibility:
+ * Add option to keep/remove the original archives.
+ * Add option to unpack files in a separate directory.
+ * Add option to unpack files in directories named after the archive names.  
+   Check for already existing target directories!
+
+Safety Backup Creator
+---------------------
+
+Purpose: 
+    Create a backup copy of a directory/file in a defined location.  E.g. as a safety copy/fallback before applying changes to a dataset etc.
+
+**Usage Example**::
+
+     $ backup.sh datadir
+     datadir contains 12 files and is 12 MB in size
+     Copying datadir to /home/fthommen/safety_backups/datadir_20-MAY-2014 ... done
+     $ backup.sh datadir2
+     datadir contains 154 files and is 3 TB in size
+     Sorry, /home/fthommen/safety_backups/datadir2_20-MAY-2014 already exists ... aborting
+     $
+
+Required tools and commands:
+    :index:`cp`, :index:`rsync`, :index:`du`, :index:`ls`, :index:`date`
+
+Things to consider:
+  * Already existing safety backups should not be overwritten!
+  * Do you or don’t you want to keep the full original path in some form? (dirname, basename)
+
+Extendibility:
+  * Add option to pack/compress the data
+
+Column Chooser (advanced)
+-------------------------
+
+Purpose:
+    Write a script, which takes a textfile with columnar layout and a header line and prints out only columns with the named headers of a textfile with columnar layout
+
+**Datafile**::
+
+    NAME    FIRSTNAME       BIRTHDATE       STREET  NO
+    Meier   Daniel  30-MAY-1990     Meyerhofstrasse 12
+    Mueller Andreas 29-FEB-1960     Bahnhofstr.     1b
+    Schmid  Ariane  1-DEC-1990      Bahnhofstrasse  13
+    vonMyra Nikolaus        15-MAR-270      Dezemberstrasse 6
+
+**Usage Example**::
+
+    $ columnchooser.sh FIRSTNAME NO
+    Daniela 12
+    Andreas 1b
+    Ariane 13
+    Nikolaus 6
+    $ columnchooser.sh CITY
+    Sorry, no column “CITY” found
+    $
+
+Required tools and commands:
+    :index:`awk`, :index:`eval`
+
+Extendibility:
+  * Add options to define alternate column separators (awk -F)
+  * Add option to customize the concatenation of the printed fields