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CST8129 Final Exam Script - Fall 2002
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Design and then write (in that order!) the following bash script that will
extract some data from a Unix-style password file and then use the data.

Each of the steps below has been written so that you can code it
independently of previous steps, using the given information.  Do as
much as you can.

Lines in the Unix password file have this 7-field colon-separated
record format:

  userid:password:uid:gid:lastname firstname:home:shell

Follow these steps to write this script:

 1.  The script you write does not need an assignment label or purpose
     section; but, it must follow the other course script writing
     guidelines, especially with regard to the interpreter line, path,
     and file creation mask. Include the associated step number in each
     of your block comments.  Remember to validate all inputs.  Issue
     appropriate useful, helpful error messages if you find incorrect,
     missing, or unusable input.
 2.  Script syntax:    $0  fullname  [ pathname ]
     Input: The script will take either one or two command line arguments.
     The first argument is a person's full name (e.g.  "Ian D. Allen"),
     and it is mandatory.  If the argument is missing, generate a useful,
     helpful error message and exit the script with status 1.  Transfer
     the first argument to a variable named fullname.
     The second command line argument is a password file pathname, and it
     is optional.  If the second argument is present, transfer it to a
     variable named pathname.  If it is missing from the command line,
     issue a good prompt and read the pathname from the user.
 3.  If the user's input is blank (the pathname is an
     empty string), set the pathname to be the usual Unix
     password file named /etc/passwd.
 4.  If the pathname is not readable, issue a useful,
     helpful error message and exit the script with status 2.
 5.  If the pathname is not a plain file, issue a
     useful, helpful error message and exit the script with status 3.
 6.  If the pathname file is zero size (is empty,
     contains no data), issue a useful, helpful error message and
     exit the script with status 4.
 7.  Convert the text string in fullname to all
     lower-case letters.
 8.  Split the text string in fullname on white-
     space, and put the first field into a variable named firstname.
 9.  Split text string in fullname again, and put the
     last field (not the second field) into a variable named lastname.
10.  Remove all the single-quote characters from the
     text in lastname (e.g. change o'donnell into odonnell).
11.  Refer to the colon-separated, 7-field record
     format of the Unix pasword file, above.  Process the password file
     named by pathname and match the user-entered lastname and firstname
     together against the field containing the same information in the
     password file.  (Get the order of the two parts of the name right
     when you do the match.) The match must be an exact match; you may
     assume that the password file has exactly one blank between the last
     and first names in the name field.  If the two user-entered names
     exactly match the corresponding two names in the name field in the
     password file, extract just the userid field from the matching line
     and save the userid into a variable named userid.  Remember: The
     field separator in the Unix password file is the colon character (":").
12.  If the above search failed to match any name,
     issue a good, useful, helpful, fully-detailed error message
     and exit the script with status 5.
13.  Create a variable named foo that contains the
     pathname /home/uuu/*foo* where the string uuu is replaced by
     the userid just found in the password file.
14.  Create a variable named bar that contains the
     pathname /home/uuu/*bar* where the string uuu is replaced by
     the userid just found in the password file.
15.  If either the pathname in variable foo or the
     pathname in variable bar are not readable, plain files,
     issue a good, useful, helpful, fully detailed error message
     and exit the script with status 6.
16.  Count the number of lines of differences between
     the two files whose names are in foo and bar and display the
     count of the lines as follows:
       File "fff" and "bbb" difference = 'nnn' lines.
     where the two strings fff and bbb are replaced by the two
     file names, and the string nnn is replaced by the line count
     of the differences between the files.
17.  If the count of the number of lines of
     differences between above two files is less than 10 lines,
     also output the line:
       Almost same: < 10 lines of difference output.
18.  Display the first 15 lines of the file whose name is in the variable
     foo, with each line preceded by its line number.

Reminder: Did you follow all the CST8129 script coding conventions?