Command Line Cygwin Tools

This document shows how to create and download project files for use with the Cygwin tools from the command line. Most students will use the CLion IDE for writing and debugging their programs, but you can use Cygwin if you prefer using command line tools. This handout is also useful for ensuring you have correctly downloaded Cygwin and all the C++ tools used in Cygwin and in CLion.

Section 1) Testing the Cygwin Toolset and Clang

In this section you will create and run a trivial C++ project/program (including editing it, and seeing how syntax errors are reported).

1. Click the (Cygwin64 Terminal icon). Perform the following actions in your come directory (mine is pattis@PATTIS-HOME).
   • Make an empty directory for all ICS-46 Projects (ics46projects) using the mkdir command.
   • Connect to the ics46projects directory using the cd command.
   • Make an empty directory for the Trivial Test Project (trivialtest) using the mkdir command.
   • Connect to the trivialtest project directory using the cd command.
   • Use any editor (vi is automatically available in Cygwin; other editors can be downloaded; Windows editors can be used) to create a main.cpp file that contains the following code (e.g., copy/paste it):

     #include <iostream>
     
     using namespace std;
     
     int main() {
         cout << "Hello, World!" << endl;
         return 0;
     }

   • Create a CMakeLists.txt file that contains the following code (e.g., copy/paste it):

     cmake_minimum_required(VERSION 3.3.2)
     
     set(CMAKE_CXX_COMPILER "/cygdrive/c/cygwin64/bin/clang++")
     set(CMAKE_C_COMPILER "/cygdrive/c/cygwin64/bin/clang")
     
     project(trivialtest)
     
     set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -std=c++11")
     
     set(SOURCE_FILES main.cpp)
     add_executable(trivialtest ${SOURCE_FILES})

   • List the contents of the ics46project/trivialtest directory storing these two files, by using the ls command.
   • Create the make files needed for this project, by using the cmake . command (reemember, you will do this just the first time you use a project).
   • List the contents of the ics46project/trivialtest directory storing the new files it creates (and the new CMakeFiles directory), by using the ls command.
   • Build the trivialtest.exe file needed to execute this program, by using the make command (you will do this each time that you modify a .cpp file in a project).
   • List the contents of the ics46project/trivialtest directory storing the new file it creates, by using the ls command.
   • Run the trivialtest.exe executable file, by using the ./trivialtest.exe command.

   The following ~/ics46projects/trivialtest Cygwin64 Terminal window shows all these actions.

   

   The lines at the top (before the pattis@PATTIS-HOME ~ prompt), are printed only the first time that you use Cygwin: they are informing you that default values for certain Unix files were created; you will not need to edit/modify these files.

2. Open a Windows file Explorer Window and navigate to the C:\cygwin\home\yourname\ics46projects\trivialtest directory, which is the same as the one manipulated using Cygwin.

   The following Explorer window should appear on your screen.

   

   You can use any combination of Windows and Cygwin commands to manipulate the files in this directory: whichever is simplest.

3. Edit, rebuild, and rerun the main.cpp program,

   • Use an editor to change the cout to print "Goodbye, World!".
   • Show the main.cpp program file, by using the more command.
   • Rebuild the trivialtest.exe file using the same make command. There is no reason to use the cmake command here: it must be used only if we change the CMakeLists.txt file.
   • Rerun the edited trivialtest.exe file, by using the ./trivialtest.exe command.

   The following ~/ics46projects/trivialtest Cygwin64 Terminal window shows all these actions.

   

4. Create a syntax error (remove the ; at the end of the cout line), and then follow the rebuilding/rerunning steps above The following ~/ics46projects/trivialtest Cygwin64 Terminal window shows all these actions.

   

   The failed results of attempting to rebuild the program appear after the make command. In this case, the Clang compiler accurately indicates the source of the error. I have lengthened the window so as not cause lines to wrap.

Section 2) Testing Downloadable Projects with the Course Libraries

In this section you will download the course libraries and then download/build/run a project that contains various programs that use these libraries.

1. Create a shortcut named ics46projects to the directory C:\cygwin\home\yourname\ics46projects and place it on your desktop near the (Cygwin64 Terminal icon).

2. Download and unzip the file libraries.zip; Copy its three directories (courselib, googletestlib, and test_all_data_types) into the directory that ics46projects shortcuts; it should already contain the trivialtest directory, created by the operations above.

   Generally, whenever you download projects, you will unzip them and then copy their directories into the directory that ics46projects shortcuts.

   The following ~/ics46projects Cygwin64 Terminal window lists these four directories.

   

3. Connect to the test_all_data_types directory, by using the cd command. Hint: type only cd te and then press the tab key and Cygwin should complete the name of this directory; generally using tab for directory/file name completion can drastically reduce your typing in Cygwin.

   List the contents of the ics46project/test_all_data_types directory, by using the ls command. Notice that this project folder contiains various .cpp files and a CMakeLists.txt file

   The following ~/ics46projects/test_all_data_types Cygwin64 Terminal window shows all these actions.

   

4. Edit the driver.cpp file by uncommenting lines 29-34, so they appear as follows

   #include "driver_set.hpp"
   
   int main() {
     ics::DriverSet d;
     return 0;
   }

5. Build and run the main.cpp program,

   • Create the make files needed for this project, by using the cmake . command (recall you will do this just the first time you use a project).
   • Build the test_all_data_types.exe file needed to execute this program, by using the make command (you will do this each time that you modify a .cpp file in a project).
   • Run the test_all_data_types.exe executable file, by using the ./test_all_data_types.exe command (remember to use command-completion to reduce your typing: but since many file names start with test_ you will have to type test_d (a unique prefix for the exe file) before pressing tab.

   The following ~/ics46projects/test_all_data_types Cygwin64 Terminal window shows all these actions.

   

   Experiment with this driver by entering commands (and their arguments, when prompted) to better understand the set data type. You can enter the q command to terminate the driver, or you can type ctrl-c to terminate the driver.

   I suggest that you try terminating the driver with a q command; then, rerun the program and terminate it with ctrl-c.

6. Recall in Item 1 (at the top of this section) you created a shortcut named ics46projects to the directory C:\cygwin\home\yourname\ics46projects; we will now briefly explore the contents of this folder. Explore (double-click) the short-cut and double-click on the test_all_data_types folder.

   The following explorer window should appear on your screen.

   

7. Double-click the test_all_data_types.exe file to run this program in Windows, outside of Cygwin. The following MS-DOS window should appear on your screen.

   

   If the error pop-window

   

   appears, you must also add C:\cygwin64\bin to the user variable PATH: see steps 15-22 in the Cygwin handout.

   Experiment with this driver by entering commands (and their arguments, when prompted); it runs as it did in Cygwin. Note that when you enter the q command or ctrl-c, the program terminates and the MS-DOS window disappears.

   So, when a program we run under Cygwin terminates, the screen retains the information printed (by cout) after the run terminates, but when we run it directly in an MS-DOS window, the window disappears after the run terminates. For example, if you find the trivialtest.exe file and run it by double-clicking this file, its MS-DOS windo will run and then immediately disappear.

8. Find the 'input files' directory in the test_all_data_types folder and copy all of its .txt data files up one level in the directory (the one that contains the test_all_data_types.exe file).

   Then, run the program (either in the Cygwin or a MS-DOS window) and issue the lf command (load from file); when prompted for the file name, just press the enter key to choose the default (loadset.txt).

   The following ~/ics46projects/test_all_data_types Cygwin64 Terminal window shows all these actions.

   

   Note that because the directory name input files contains a space, it appears in single quotes ('input files') and must appear in single quotes in all Cygwin commands.

   IMPORTANT: If a program reads data files, the root directory for the specifying the files is the directory in which the .exe file appears. It is simplest to copy all the data files into this directory. An alternative would be to leave the files in the input files directory, and enter their names like input files/loadset.txt (note no quotes here: this is not a Cygwin command).

9. A typical project folder may have more than one .cpp file with a main function (as test_all_data_types has). Only one of these .cpp files can have its main function uncommented, otherwise the build will fail. When working on project, it is typical to
   1. Comment-out code in one .cpp file.
   2. Uncomment code in another .cpp file.
   3. Rebuild/Rerun the newly uncommented .cpp file.

   In the test_all_data_types project folder, the driver.cpp file has many main functions: we uncommented one (in step 4) to allow us to run the Set driver. If more than one main function is uncommented, attempting to build the code will result in the compiler specifying a redefinition of 'main' error.

   The test_all_data_types project folder also contains many .cpp files (their names all start with test) that each contain one main function (each is a Googletest for one data type). If more than one file contains a main function, attempting to build the code will result in the linker specifying a multiple definition of 'main' error.

   To switch this project from running the Set driver to the Set Googletest

   1. Edit the driver.cpp file and comment-out lines 29-34.
   2. Edit the test_set.cpp file and uncomment all its lines.
      Most program editors have a special command that allows commenting on selected lines to be toggeled.

   Rebuild/Rerun the newly uncommented .cpp file.

   The following ~/ics46projects/test_all_data_types Cygwin64 Terminal window shows all these actions.

   

We are now at the end of this handout. You will not need to repeat the first two sections during the course, but you will frequently download project folders and use them as demonstrated in section 2.