Lecture 25 – Nov 8th, 2019


  1. Log in to clyde.
  2. Download data.txt using wget(1) or curl(1).


  1. data.txt consists of a table of information regarding government offices including phone numbers of the administrators in charge of the office. Each line in the file consists of a number of tab-delimited fields. The first line of the file gives the name of each field.

    Write a single regular expression for use with grep -E to output all of the lines in data.txt containing phone numbers in the 202 and 314 area codes.

    If you use $ grep -E --color regex data.txt it will highlight the matches in the line so you can be sure it’s matching the correct things. There should be 42 matching lines.

  2. Write a sed(1) substitution command to print out the Symbol corresponding to each organization in the Archives I building.

    You’re going to want to use the -n option to sed(1) to suppress printing lines by default and use the p flag to the substitution command to print lines on which a substitution was performed. In other words, you want to use sed -E -n and the substitution should be s/regex/replacement/p.


    $ sed -E -n '/\tArchives I\t/p' data.txt

    uses the p (print) command to print all lines matching Archive I surrounded by tabs. Replace the p with a suitable s///p to extract just the symbol from those lines, assuming it’s not blank.

    There are 16 such symbols. The first three lines of output should be

  3. Write a sed(1) substitution command that matches lines with phone numbers in the 202 and 314 area codes and has a nonblank person in charge. The substitution command should replace each matching line with
    [Symbol] In Charge: Phone

    where Symbol, In Charge, and Phone correspond to the fields in the line with those names.

    The first two lines of output should be

    [N] David S Ferriero: 202-357-5900
    [ND] Debra Steidel Wall: 202-357-5900

    and there should be 39 lines in total.

    Note that some of the lines with telephone numbers in the appropriate area codes do not have a person in charge and thus should not be printed. The line with the Symbol AFN-MR is an example of one that should not be printed.

    This one is complicated, try building it up your regular expression piece by piece. The fields are separated by tabs and you can use \t to match a tab.

  4. Repeat 2 and 3, but use awk(1) instead of sed(1).