Assignment 3 and 4: Optional Scripting
Complete assignment due: Thursday, Sep. 25th, 8:00 p.m.
The Korn shell scripts in this assignment explore the ways to handle options on the command-line. These are the “dash” options, such as -i or -q. The Korn shell supports an expanded version of getopts, which is a tool that aids in processing the options. We will see the use of getopts in C programs later in the semester.
The first script uses a simpler version of getopts, that allows single character options. The options can occur individually on the command line, as in:
ksh fileOpts.ksh -c -f filename1 filename2
or they can be grouped together, as in
ksh fileOpts.ksh -cf filename1 filename2
The second script uses an expanded version of getopts that can handle -- arguments, such as
now.ksh --today --month
which has the same meaning as
now.ksh -t -m
The expanded version also supports the --help and --man options.
Problem 1: File Options
Write a Korn shell script named fileOpts.ksh. The script will perform various actions on each of its arguments. Which operations are performed will be determined by the options specified. The synopsis of the command is:
ksh fileOpts.ksh [-c] [-l] [-p #] [-f]  [-r filename] [ file ... ]
The four command-line options have the following meanings:
  1. •-c Run wc on each of the file arguments
  2. •-l Run ls -l on each of the file arguments
  3. •-p Print some or all of the contents of each of the file arguments. There will be a numeric argument provided. When the numeric argument is 0, use cat to print the entire file. When the argument is positive, use head to print the first part of the file. When the argument is negative, use tail to print the last part of the file. For head and tail, the numeric argument specifies the number of lines to print.
  4. •-f Run file on each of the file arguments.
  5. •-r Send the standard output of all the requested operations to the specified file.
When multiple options are chosen and multiple filenames are specified, fileOpts.ksh will perform all of the options on the first file, followed by all of the options on the second file, etc.
Some examples:
$ export books="/home/cs352/fall08/books/"
$ ksh fileOpts.ksh -c $books/sawyer.txt $books/gettysburg.txt
  8303  71910 400480 /home/cs352/fall08/books/sawyer.txt
  23  280 1495 /home/cs352/fall08/books/gettysburg.txt
$ ksh fileOpts.ksh -l $books/sawyer.txt $books/gettysburg.txt
-rw-rw-r-- 1 patrick cs352f08 400480 2007-02-05 17:26 /home/cs352/fall08/books/sawyer.txt
-rw-rw-r-- 1 patrick cs352f08 1495 2008-08-26 15:19 /home/cs352/fall08/books/gettysburg.txt
$ fileOpts.ksh -f $books/*
/home/cs352/fall08/books/gettysburg.txt: ASCII English text
/home/cs352/fall08/books/hesperus.txt: ASCII English text
/home/cs352/fall08/books/lgDictionary.txt: ASCII text
/home/cs352/fall08/books/longfellow.txt: ASCII English text
/home/cs352/fall08/books/mobydick.txt: ASCII English text
/home/cs352/fall08/books/mohicans.txt: ISO-8859 English text
/home/cs352/fall08/books/musketeers.txt: ASCII English text
/home/cs352/fall08/books/noSpace.txt: ASCII text
/home/cs352/fall08/books/raven.txt: ASCII English text
/home/cs352/fall08/books/sawyer.txt: OS/2 REXX batch file text
/home/cs352/fall08/books/words: ASCII C program text
$ ksh fileOpts.ksh -p 3 $books/gettysburg.txt $books/raven.txt
Gettysburg Address
 
        Four-score and seven years ago, our fathers brought forth on this
Edgar Allan Poe: The Raven
$ ksh fileOpts.ksh -p -4 $books/gettysburg.txt $books/raven.txt
measure of devotion - that we here highly resolve that these dead shall
not have died in vain - that this nation, under God, shall have a new
birth of freedom - and that government of the people, by the people, for
the people, shall not perish from the earth.
And his eyes have all the seeming of a demon's that is dreaming,
And the lamp-light o'er him streaming throws his shadow on the floor;
And my soul from out that shadow that lies floating on the floor
Shall be lifted - nevermore!
$ ksh fileOpts.ksh -clfp 4 $books/gettysburg.txt $books/raven.txt
  23  280 1495 /home/cs352/fall08/books/gettysburg.txt
-rw-rw-r-- 1 patrick cs352f08 1495 2008-08-26 15:19 /home/cs352/fall08/books/gettysburg.txt
Gettysburg Address
 
        Four-score and seven years ago, our fathers brought forth on this
continent a new nation, conceived in liberty and dedicated to the
/home/cs352/fall08/books/gettysburg.txt: ASCII English text
 127 1128 6261 /home/cs352/fall08/books/raven.txt
-rw-rw-r-- 1 patrick cs352f08 6261 2006-08-21 20:58 /home/cs352/fall08/books/raven.txt
Edgar Allan Poe: The Raven
 
 
Once upon a midnight dreary, while I pondered, weak and weary,
/home/cs352/fall08/books/raven.txt: ASCII English text
$ ksh fileOpts.ksh -cfp -2 -r zap.out $books/gettysburg.txt $books/raven.txt
$ cat zap.out
  23  280 1495 /home/cs352/fall08/books/gettysburg.txt
birth of freedom - and that government of the people, by the people, for
the people, shall not perish from the earth.
/home/cs352/fall08/books/gettysburg.txt: ASCII English text
 127 1128 6261 /home/cs352/fall08/books/raven.txt
And my soul from out that shadow that lies floating on the floor
Shall be lifted - nevermore!
/home/cs352/fall08/books/raven.txt: ASCII English text
The following script gives a simple example of how to use getopts in a Korn shell script. In addition to the example, the manpage for ksh provides an overview. Search for the string “getopts”; the third occurrence will be the section that describes it. The manpage also describes the ${OPTIND} and ${OPTARG} variables.
This simpleOpts.ksh script is available in ~cs352/fall08/UnixExamples.
#!/bin/ksh
 
a="not chosen"
b="not chosen"
b_arg="not chosen"
c="not chosen"
c_arg="not chosen"
d="not chosen"
 
# The while loop will execute until there are no more command-line
# arguments that start with a hyphen.  The options can be grouped
# together, as in:  ksh simpleOpts.ksh -ad
# The # following b indicates that when -b is present, it has a
# required numeric argument following it.
# The : following c indicates that when -c is present, it has a
# required argument following it.  Typically, this will be a string,
# such as a filename.
# In the case statement, the variable ${OPTARG} is the argument
# following the current option being processed.  It can be used to
# get a numeric or text argument following a parameter.
while getopts "ab#c:d" optchar ; do
   case ${optchar} in
      a)  a="selected"
          ;;
      b)  b="selected"
          b_arg=${OPTARG}
          ;;
      c)  c="selected"
          c_arg=${OPTARG}
          ;;
      d)  d="selected"
          ;;
      # When getopts encounters an option that is not listed in its
      # options string, ${optchar} will be assigned the ? character.
      # getopts will print to stderr an error message about the
      # invalid option.  This arm of the case statement can be used
      # to print additional error messages, such as a Usage statement.
      # Depending on circumstances, the programmer may, or may not,
      # choose to exit at this point.
      \?) echo "error message goes here"
          exit 1
          ;;
   esac
done
 
# The shift statement following the while loop will shift the
# options that have been processed.  ${OPTIND} is the index of the
# next command-line argument to be processed.
shift $(( ${OPTIND} - 1 ))
 
# Some print statements to show values that might have been acquired
# while processing options.
echo a is ${a}
echo b is ${b}
echo b_arg is ${b_arg}
echo c is ${c}
echo c_arg is ${c_arg}
echo d is ${d}
 
# Since we shifted above, $1 is now the first command-line argument
# following the options.  Here is a simple loop to print those
# arguments, if any.
echo "The remaining command-line arguments are:"
for i in "$@"; do
   echo "'"${i}"'"
done
 
exit 0;
Turnin: Use turnin to turn in your completed fileOpts.ksh file. The command is:
turnin 352assign3 fileOpts.ksh
See the man page for the turnin program for details on what turn in can do and how you can confirm that your file was turned in.