Run C programs in Ubuntu
How To

Running C Programs in Ubuntu Command Line

Pranav Krishna
Pranav Krishna

Table of Contents

While there are many ways to execute a C program in Linux, using the terminal is the easiest of all, even for beginners.

It may seem scary, but it is really not. To run C programs in Ubuntu, you need to install the compiler first.

In this guide, you will learn to:

  • Install GCC compiler (to compile the program)
  • Execute the C program

Let's C (yeah! I am funny).

Installing the compiler - gcc

The GCC compiler used to compile C-programs into executable files is available in the official repositories of apt. Installing gcc in Ubuntu is fairly simple.

First, update the repositories:

sudo apt update

Then install GCC via:

sudo apt install gcc
Install GCC from the command line
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Optional: If you want to install an array of all the C and C++ related tools, you can install the clang package rather than gcc alone. It includes all other compiling tools too.

Executing a C program in Ubuntu

Once you are ready with the compiler, you can write programs and compile and execute them.

You specify the input C file name and an output name (usually recommended to keep the same name as the program filename but without the .c extension).

gcc <filename>.c -o <filename>

The generated output file is executable and you can run this file to actually run your program.

./filename

Example

Open any text editor and write a simple C program.

For example, here, I used Nano editor to edit the file in command line and wrote a C program that prints the value of sin30:  

#include<stdio.h>
#include<math.h>

void main()
{
	printf("Yes, this is a C program :) \n");
    printf("sin(30deg) = %f",sin(M_PI/6));
}
C program (actual)

Save the file with a desired name and with a .c extension.

The example C program (with an error)

To compile this program, all you have to do is execute the GCC compiler in the following manner:

gcc c-program.c -o c-program

If your code is correct,  it won't show any errors, and you will be given an executable file for your program.

You can always use the ls command to check the file contents of the directory:

ls
check the name of the executable file after the compilation

Now, all there's left is to execute the file:

./c-program
Compile and execute

To C or not to C ...

If there's an error in the C program file, then it will not be compiled, obviously. Also, the error(s) are displayed as shown below.

Error in the program is highlighted

In my case, the error was in the first line where I named the header file stdio incorrectly. Which was supposed to be named as stdio.h .

Sure, you can have one or more errors which will be reflected by the compiler.

On a similar note, how about learning about running Python programs in Ubuntu?

How to Run Python Programs in Ubuntu Command Line
Got a Python script? Learn how to run Python programs in Ubuntu command line.

These are the simple steps to compile C programs in Ubuntu. Leave a comment if there's any doubt.