Lab Assignment, Foundations of Computing

Revised March 10, use your browsers Reload or Refresh button to get the latest version.

Write an awk program to check file type.

Name the program afile. The program reads from standard input. The program writes one line containing one word to standard output, indicating the type of the input: HTML, Scheme, Numeric, Text, or Other.

This example shows one way to run the program on a file named foo.dat. Here afile detects that foo.dat contains numeric data:


    $ cat foo.dat | awk -f afile

    Numeric

The criteria used to identify each type of file are described in these pages, and summarized in line here:

HTML - contains an <HTML> or <html> tag anywhere in the file
Scheme - contains the pattern (define ( anywhere in the file (note the second parentheses)
Numeric - contains only the digits 0 - 9 and the special characters $ % * . / ^ = and the space character.
Text - contains only bytes with (octal) ASCII codes in the range 000 - 177
Other - anything else, including GIF's, JPEG's, binary executables etc.

To understand the definition of the text file type, it may be useful to refer to a table of ASCII codes. Here are some samples from the web:

This table shows the octal codes.
This table shows the control character names and control key sequences but doesn't show the octal codes.
This table shows the extended 8-bit codes (plus a lot of annoying ads).

The file types are not mutually exclusive -- the first three file types are also text files -- so your program must test for file type in this order: HTML, Scheme, Numeric, Text and Other. So Text really means the file is a text file which is not also an HTML file, Scheme file, or Numeric file. The Other category should include binary files including GIF's, JPEG's, executable code (as found in the files in the bin directories) etc.

The assignment is due in the lab on Thursday, March 15.