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Getting Your C Compiler Installed

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Brian "Beej Jorgensen" Hall edited this page Apr 22, 2019 · 39 revisions

Instructions and pitfalls in getting your C compiler installed.

General Build Instructions

(See the sections below for specific per-platform instructions.)

Here's a sample C program. You should type this in and save it as hello.c with your favorite IDE (e.g. VS Code) or editor (e.g. vim, emacs, etc.):

#include <stdio.h>

int main(void)
{
    printf("Hello, world!\n");

    return 0;
}

To build your C program from the command line (Bash shell or Terminal), first use the cd (change directory) command to switch to the directory (when I was a kid, folders were called directories) that has your hello.c in it. Then build with:

gcc -Wall -Wextra -o hello hello.c

To run it from the command line:

./hello

(In PowerShell, use .\hello.)

A More Advanced Test

If you want to make doubly sure that your environment will work for everything we need it to do at Lambda School, try compiling and running this program, ctest.c:

#include <stdio.h>
#include <unistd.h>
#include <stdlib.h>
#include <sys/wait.h>

int main(void)
{
    printf("This program should print 1,2,3 in order.\n");
    printf("If it does, you're good to go with Lambda School C.\n\n");
    
    printf("1\n");

    if (fork() == 0) {
        sleep(1);
        printf("2\n");
        exit(0);
    }

    wait(NULL);

    printf("3\n");

    return 0;
}

General Pitfalls

  • If you accidentally tell gcc to overwrite your .c file with the -o (output) flag, you'll get errors. And your source code will be overwritten!

    # WRONG!!
gcc -Wall -Wextra -o foo.c foo

# RIGHT!!
gcc -Wall -Wextra -o foo foo.c

  • If you're on Windows and get errors about WinMain, make sure you have a main() function in your code! There are also other reasons you might see this error. Read on, below.

  • If you're on Windows, you might also want to run

    git config --global core.autocrlf false

    This makes it so git doesn't automatically set newlines to Windows-style when it clones a repo. VS Code and other editors should work fine with Unix-style newlines. (And Windows-style newlines cause bash scripts to break.)

macos

Option A: Command Line Tools

  • Open a Terminal.
  • Run xcode-select --install.
  • When prompted to install the developer command line tools, click Install.

Option B: Full XCode install

If you're going to install XCode anyway for some other reason, you can use these instructions:

  • Install XCode from the AppStore.
  • Open a Terminal.
  • Run gcc.
  • When prompted to install the developer command line tools, click Install.

Windows

The two options for Windows that we know of for building the Unix-like code we play with at Lambda School are WSL and Cygwin. MinGW is too minimalist for our use.

Option A: WSL

This is the recommended option, but is only available for Windows 10 and higher. Earlier versions must use Cygwin, below.

The Windows Subsystem for Linux is an officially-supported binary compatibility layer for Linux apps running on Windows.

This basically gives you a mini Linux install. Ubuntu is recommended, but not required.

Requires Windows 10.

  • Install WSL--we recommend using Ubuntu as your distribution.
    • Check your build number. If it is pre-16215, you'll need to turn on developer mode, as per the above instructions.
  • Run bash from the command prompt or start menu.
  • Run sudo apt install build-essential to install GCC.
  • See below if you get a long string of 404 errors.

Drive Access

  • To get to your Windows drive from Bash, type: 
    cd /mnt/c/Users/YourUserName
  • There is no supported way to access your WSL drive from Windows command prompt. Don't do it.

VSCode and WSL

  • Keep your program files on your Windows drive.

  • Run VSCode as normal.

  • You can bring up a bash shell then switch to your Windows drive, as outlined above. Then run gcc or whatever you need to.

  • To get VSCode's integrated terminal to use WSL bash, add the following to your VS Code user settings:

    "terminal.integrated.shell.windows": "C:\\Windows\\System32\\bash.exe"

    More info here.

  • Unrelated to C programming, VSCode has some integrated WSL support for running the node debugger. See launching WSL node from the VSCode debugger.

WSL Pitfalls

  • If you later get errors about make not being installed, type sudo apt-get make.
  • If you get 404s when doing sudo apt-get, try: 
    sudo apt-get update && sudo apt-get install X

Option B: Cygwin

Cygwin is a library compatibility layer for building and running Linux apps.

If you're not running Windows 10 or higher, this is the only option.

WARNING!!! Any programs you compile with Cygwin will only run within Cygwin. They will not function in regular Windows/DOS, Linux, or Mac.

  • Install Cygwin.
  • Launch a Windows command prompt.
  • Install the necessary packages by running the Cygwin Setup utility. 
    setup-x86_64.exe -q -P wget -P gcc-g++ -P make -P diffutils -P libmpfr-devel -P libgmp-devel -P libmpc-devel
    • If you're using PowerShell, you might have to put a path in front of the setup command, e.g. 
      .\setup-x86_64.exe etc. etc.
    • 32-bit users would run: 
      setup-x86.exe -q -P wget -P gcc-g++ -P make -P diffutils -P libmpfr-devel -P libgmp-devel -P libmpc-devel
  • Add the appropriate entry at the front/top of your Windows path: 
    C:\cygwin64\bin
    or, for 32-bit: 
    C:\cygwin\bin
    If you are editing the entire PATH variable at once, remember that entries are separated from one another by ;s.
  • Launch Cygwin-Terminal from its icon.

Drive Access

  • To get to your Windows drive from Bash, type:

    cd /cygdrive/c/Users/YourUserName

    or

    cd c:/Users/YourUserName

  • To get to your Cygwin drive from Windows command prompt, type:

    cd c:\cygwin64\home\youruser

    On 32-bit systems, this might be:

    cd c:\cygwin\home\youruser

VSCode and Cygwin

  • Keep your files either on your Windows drive or Cygwin drive. Access them as per above.
  • Run VSCode as normal.
  • Run gcc from the Cygwin Terminal bash shell.
  • To get VSCode's integrated terminal to use Cygwin bash, add the following to your VS Code user settings: 
    "terminal.integrated.shell.windows": "C:\\cygwin\\bin\\bash.exe",
"terminal.integrated.env.windows" {"CHERE_INVOKING": "1"},
"terminal.integrated.shellArgs.windows": ["-l"]
    More info here.

Cygwin Pitfalls

  • If you have MinGW also installed, make sure that the Cygwin binaries are first in your PATH. If not, it will run the wrong GCC on the command line and you'll receive an error about WinMain not being found. Uninstall MinGW, per below.

  • If you get the base mismatch error:

    C:\cygwin64\bin\make.exe: *** fatal error - cygheap base mismatch detected

It could be because of an incompatibility with MinGW. Recommend uninstalling MinGW, or at least make sure Cygwin is in your PATH first, as above.

  • Another way to get an error about WinMain not being found is if you accidentally specify your source .c program as the output file with -o. See General Pitfalls, above.

  • If gcc gives you an error along these lines:

       0 [sig] make 7332 get_proc_lock: Couldn't acquire sync_proc_subproc for(5, 1), last 7, Win32 error 0
1324 [sig] make 7332 proc_subproc: couldn't get proc lock. what 5, val 1

    disable your Avast (or other) anti-virus software.

Not Sufficient: MinGW

MinGW does not support fork(), so will not work for LS classes.

Having a MinGW install can interfere with the workings of Cygwin. You might get errors related to an undefined WinMain. Here are instructions for uninstalling MinGW.

Not Sufficient: Visual Studio Community, or other Visual Studio

While great for building Windows apps, our learning takes place in Unix-like environments. As such, Visual Studio won't work. WSL or Cygwin is necessary for that environment.

Linux/Unix-likes

Google for specific instructions using your distribution name, e.g. ubuntu gcc install.

Ubuntu/clang Pitfalls

If you get an error like this during a build:

/usr/bin/ld: cannot find crti.o: No such file or directory

Add the following to your ~/.bashrc or ~/.bash_profile and relaunch your shell:

export LIBRARY_PATH=/usr/lib64:/usr/lib32:$LIBRARY_PATH

Raspberry Pi

A modern Raspberry Pi image comes with gcc ready to go out of the box. You'll need an external HDMI monitor, USB keyboard, and USB mouse.

Once you have it set up, you can enable ssh access to the Pi and then log into it from your main computer.

Raspberry Pi Pitfalls

  • If your mouse is behaving sluggishly, add the following line to /boot/cmdline.txt then reboot: 
    usbhid.mousepoll=0
    If that breaks your mousewheel, another value that might work is usbhid.mousepoll=4.

Virtual Machines (Windows, macos)

Instead of the above options for Windows and Mac, you could opt to install a virtual machine (VM) on your computer. This is like giving yourself a completely separate new computer to run another OS on (e.g. Linux).

This is more work than any of the approaches, above, but does give you a complete Linux system and GUI. A GUI is not required for what we do at Lambda School, so this would be more of a labor of love. If you just want the command line tools and VS Code, consider WSL or Cygwin instead.

Popular VMs are VirtualBox (free) or VMWare.

If you go this route, you'll be following the terse Linux instructions, above.

To run a VM, you'll need to set aside some of your system RAM and disk to support it. We'd recommend at least 12 GB total RAM, with 4 GB for Linux and 8 GB for Windows. 20 GB of disk reserved for Linux should be sufficient.

4 GB for Linux is really a minimum. 16 GB total system RAM evenly split between Windows and Linux is better.

You'll also need to choose a Linux distribution and install it. Mint is popular, Ubuntu is user-friendly, Arch is low-level. There are hundreds of distributions. Virtually all of them will work for Lambda School.

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