Merge branch 'master' of https://github.com/FOSSEE/sees

3 files changed, 82 insertions, 15 deletions

diff --git a/ult/exercises.rst b/ult/exercises.rst
index b6be986..9898b39 100644
--- a/ult/exercises.rst
+++ b/ult/exercises.rst
@@ -57,7 +57,7 @@ Session-1
 
 #. Change ownership of the file ``test`` to some other user (if exists).
 
-#. Count the number of files in a directory. 
+#. Count the number of files (files, sub-directories, etc.) in a directory. 
 
 #. Create a new file ``alice.txt`` by concatenating the first 30 lines
    and the last 40 lines of ``wonderland.txt``.
@@ -73,7 +73,9 @@ Session-2
 
 0. Read through the section ``REGULAR EXPRESSIONS`` in ``man grep``
 
-1. grep the marks of the students who scored above 75 in atleast one
+#. Read through in ``man expr``
+
+#. grep the marks of the students who scored above 75 in atleast one
    subject. 
 
 #. grep the marks of all the students whose names begin with an 's'
diff --git a/ult/handout.rst b/ult/handout.rst
index b72dbdc..5ef762a 100644
--- a/ult/handout.rst
+++ b/ult/handout.rst
@@ -1785,6 +1785,41 @@ So, these are all the paths that are searched, when looking to execute a
 command. If we put the results.sh script in one of these locations, we
 could simply run it, without using the ``./`` at the beginning. 
 
+Variables
+---------
+
+As expected, it is possible to define our own variables inside our shell
+scripts. For example,
+
+::
+
+    name="FOSSEE"
+
+creates a new variable ``name`` whose value is ``FOSSEE``. To refer to this
+variable, inside our shell script, we would refer to it, as ``$name``.
+**NOTE** that there is no space around the ``=`` sign. 
+
+::
+
+    ls $name*
+
+It is possible to store the output of a command in a variable, by enclosing
+the command in back-quotes. 
+
+::
+
+    count=`wc -l wonderland.txt`
+
+saves the number of lines in the file ``wonderland.txt`` in the variable
+count. 
+
+Comments
+--------
+
+The ``#`` character is used to comment out content from a shell script.
+Anything that appears after the ``#`` character in a line, is ignored by
+the bash shell. 
+
 Control structures and Operators
 ================================
 
@@ -1910,6 +1945,15 @@ dummy or a loop variable. It can then be used to refer to the element of
 the list that is currently being dealt with. We could, obviously, use
 something as lame as ``i`` in place of ``animal``.
 
+To generate a range of numbers and iterate over them, we do the following. 
+
+::
+
+    for i in {5..10}
+    do
+    echo $i
+    done
+
 Now, we use a ``for`` loop to list the files that we are interested in.
 
 ::
diff --git a/ult/ult.tex b/ult/ult.tex
index 62117eb..a94dc14 100644
--- a/ult/ult.tex
+++ b/ult/ult.tex
@@ -679,7 +679,7 @@
 \begin{frame}[fragile]
   \frametitle{Redirection and Piping}
   \begin{lstlisting}
-    $ cut -d " " -f 2- marks.txt \
+    $ cut -d " " -f 2- marks1.txt \
     > /tmp/m_tmp.txt
     $ paste -d " " students.txt m_tmp.txt
   \end{lstlisting} % $
@@ -687,7 +687,7 @@
   or
 
   \begin{lstlisting}
-    $ cut -d " " -f 2- marks.txt \
+    $ cut -d " " -f 2- marks1.txt \
     | paste -d " " students.txt -
   \end{lstlisting} % $
 
@@ -745,10 +745,10 @@
   \item Error message is redirected, in the second case
   \end{itemize}
   \begin{lstlisting}
-    $ cut -d " " -c 2- marks.txt \
+    $ cut -d " " -c 2- marks1.txt \
       > /tmp/m_tmp.txt
 
-    $ cut -d " " -f 2- marks.txt 1> \
+    $ cut -d " " -f 2- marks1.txt 1> \
       /tmp/m_tmp.txt 2> /tmp/m_err.txt
   \end{lstlisting} % $
   \begin{itemize}
@@ -763,7 +763,7 @@
 \begin{frame}[fragile]
   \frametitle{Piping}
   \begin{lstlisting}
-    $ cut -d " " -f 2- marks.txt \
+    $ cut -d " " -f 2- marks1.txt \
       | paste -d " " students.txt -
   \end{lstlisting} % $
   \begin{itemize}
@@ -852,7 +852,7 @@
   \item Command below prints student marks, sorted by name
   \end{itemize}
   \begin{lstlisting}
-    $ cut -d " " -f 2- marks.txt \
+    $ cut -d " " -f 2- marks1.txt \
       | paste -d " " students.txt - \
       | sort
   \end{lstlisting} % $
@@ -868,7 +868,7 @@
   \item The command below sorts based on marks in first subject
   \end{itemize}
   \begin{lstlisting}
-    $ cut -d " " -f 2- marks.txt \
+    $ cut -d " " -f 2- marks1.txt \
       | paste -d " " students.txt -\
       | sort -t " " -k 2 -rn
   \end{lstlisting} % $
@@ -887,7 +887,7 @@
   \item Command below searches \& shows the marks of Anne alone 
   \end{itemize}
   \begin{lstlisting}
-    $ cut -d " " -f 2- marks.txt \
+    $ cut -d " " -f 2- marks1.txt \
     | paste -d " " students.txt - 
     | grep Anne
   \end{lstlisting} % $
@@ -902,7 +902,7 @@
   \item \texttt{-i} for case-insensitive searches
   \end{itemize}
   \begin{lstlisting}
-    $ cut -d " " -f 2- marks.txt \
+    $ cut -d " " -f 2- marks1.txt \
     | paste -d " " students.txt - 
     | grep -i Anne
   \end{lstlisting} % $
@@ -911,7 +911,7 @@
   \item To see everyone's marks except Anne's
   \end{itemize}
   \begin{lstlisting}
-    $ cut -d " " -f 2- marks.txt \
+    $ cut -d " " -f 2- marks1.txt \
     | paste -d " " students.txt - 
     | grep -iv Anne
   \end{lstlisting} % $
@@ -989,7 +989,7 @@
   \begin{lstlisting}
     #!/bin/bash
     mkdir ~/marks
-    cut -d " " -f 2- marks.txt \
+    cut -d " " -f 2- marks1.txt \
     | paste -d " " students.txt - \
     | sort > ~/marks/results.txt
   \end{lstlisting} % $
@@ -1013,6 +1013,21 @@
 \end{frame}
 
 \begin{frame}[fragile]
+  \frametitle{Variables \& Comments}
+  \begin{lstlisting}
+    $ name=FOSSEE
+    $ count=`wc -l wonderland.txt`
+    $ echo $count # Shows the value of count
+  \end{lstlisting} % $
+  \begin{itemize}
+  \item It is possible to create variables in shell scripts
+  \item Variables can be assigned with the output of commands
+  \item \alert{NOTE:} There is no space around the \texttt{=} sign
+  \item All text following the \texttt{\#} is considered a comment
+  \end{itemize}
+\end{frame}
+
+\begin{frame}[fragile]
   \frametitle{\texttt{echo}}
   \begin{itemize}
   \item \texttt{echo} command prints out messages
@@ -1020,7 +1035,7 @@
   \begin{lstlisting}
     #!/bin/bash
     mkdir ~/marks
-    cut -d " " -f 2- marks.txt \
+    cut -d " " -f 2- marks1.txt \
     | paste -d " " students.txt - \
     | sort > ~/marks/results.txt
     echo "Results generated."
@@ -1036,7 +1051,7 @@
   \begin{lstlisting}
     #!/bin/bash
     mkdir ~/marks
-    cut -d " " -f 2- marks.txt \
+    cut -d " " -f 2- marks1.txt \
     | paste -d " " students.txt - \
     | sort > ~/marks/$1
     echo "Results generated."
@@ -1211,6 +1226,12 @@
   \item Loop over the list; \texttt{animal} is a dummy variable
   \item Echo value of \texttt{animal} ---  each name in list
   \end{itemize}
+  \begin{lstlisting}
+    for i in {10..20}
+    do 
+    echo $i
+    done
+  \end{lstlisting} % $
 \end{frame}
 
 \begin{frame}[fragile]