Module $1($review of CIS $18$A$)$

From the practice exercise, you should have already set up an easy way to copy files from the $/$home$/$distribution$/$cnguyen$/$cis$18$b directory on voyager, without having to type the long path name every time.

$1.$ If you are not already at your home directory, go to your home directory and don$$t change directory for the rest of this module $1$ lab. Show the absolute path of your current directory.

$2.$ Use the set up from the practice exercise that$$s described above, copy the file lab$1-2$in from the cis$18$b directory to your current directory.

$3.$ Create a subdirectory called lab$1-2$dir and an empty file named f$1.$

$4.$ Don$$t use a text editor, create a file called f$2$ in the directory lab$1-2$dir and put your user id $($login id$)$ and your current shell in file f$2.$ You should not have to type in your user id or your current shell, let the system fill in these $2$ values. Don't forget that this step should be done on one command line, just like all the other steps.

$5.$ Use the correct option of the ls utility to list files f$1,$ f$2,$ and lab$1-2$in$,$ where the size in bytes is shown. Only these $2$ files should be shown in the output.

For the next $3$ steps, use the file lab$1-2$in and use only the filters that are reviewed in Module $1$ lecture notes.

Don$$t use sed or awk, there will be plenty of opportunities for these utilities later.

lab$1-2$in is a text file with information on big US cities. Each line has $3$ fields: city name, high elevation, low elevation. The fields are separated by a semicolon.

$6.$ Show how many cities there are in the file lab$1-2$in$.$ Use a utility to count the cities, you should not have to do the counting. The output should be one line, with a text explanation, such as: Number of big cities is $50$

Note that there is no filename in the output.

$7.$ For the city with the highest high elevation, show the city name and its elevation $($only these $2$ fields should be in the output$)$ and the $2$ fields should be separated by a colon $($:$).$

$8.$ Show the city name of all cities with a low elevation below sea level $($a negative value$).$ The output should only be the city names. $($Hint: use a regex to describe a negative number. You should not have to search through the file yourself for negative numbers to print the city names.$)$

In the following step you confirm that you have the basic programming skills needed for this class.

$9.$ Download the pseudocode at the link "Programming self$-$test".

Use any programming language you like, write code to implement the pseudocode in a text file. The code doesn't have to have perfect syntax, but you should show the language construct to do looping, if statement, array, etc.

$10.$ If you've been copying and pasting the command lines and output to an output file on your computer, then copy and paste the code of step $9$ into your output file.

If you$$ve been using the script utility to record all screen output, then stop the script recording. Next, use vim to open a text file and go to insert mode. Then use control$-$c$/$command$-$c to copy your code of step $9$ and then use control$-$v$/$command$-$v to paste the code into the vim file and save it$.$ Append the vim file to your script output file so the code is in your output file.

Save the lab$1-2.$txt output file before continuing to module $2.$

Module $2($regex$,$ egrep, find$)$

$-$ Use the same lab$1-2$in file in Module $1$ for steps $1-5$

$-$ Take advantage of options of the utilities to simplify your regex and your command line

$-$ Don't use sed or awk

$-$ All steps in this lab should be done with one command line per step, with no temporary files.

For all lines in lab$1-2$in:

$1.$ Show all lines where the city name starts with 'San' $($uppercase or lowercase$).$

$2.$ Show all city names that have $2$ words in the name. Only the city names should be in the output.

Hint $1$: both "los angeles" and "Washington D$.$C$."$ have $2$ words, how do you determine when it's $2$ words?

Hint $2$: make your regex as short as possible.

$3.$ Show the count of cities where the high elevation is not in the hundreds $($or a $3-$digit number$).$ The output should be just a number.

$4.$ Show the line numbers of cities where the low elevation is $0$ or at sea level. The output should be line numbers only.

Working with your current files:

$5.$ Show the filename of all files in your home directory and all subdirectories, where the file content contains semicolons. Note that it$$s the file content, not the filenames, that contains semicolons. The output should just be the filenames.

$6.$ Show the long listing of all regular files in your home directory $($only your home directory, not subdirectories$)$ that have a modified time of more than $2$ hours.

$7.$ For your home directory and all its subdirectories, find all files with filenames that contain at least $1$ digit, and change their permission so only you have read and write access and everyone else has no access.

$8.$ For your home directory and all its subdirectories, find all regular files that are empty and delete them, using the