How to see output of C program in Linux or UNIX

I am a new user of Linux operating system but not to C programming language. At my university we are using Turbo C compiler under DOS/Windows XP to write and compile C programs. Under Linux I wrote a small program called test.c. How do I compile and see the output of C program in a Linux when using Fedora Linux?

Under Linux you need to use the cc/gcc (GNU project C and C++ compiler) command to compile a program written in C or C++. When you compile a program it generates an executable file called a.out.

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Syntax

The syntax is:
gcc -o output-file program.c
OR
cc -o output-file program.c
OR
make program.c

Sample code

Here is a sample C code called test.c that I am going to compile using GNU C compiler:

/* Purpose: A simple program to get name and information about current kernel
 * using uname(2) on a Linux.
 * Author: Vivek Gite <https://www.cyberciti.biz>
 */
#include <sys/utsname.h>
#include <stdio.h>
#include <unistd.h>
#include <stdlib.h>
#include <errno.h>
#include <string.h>
#include <sys/utsname.h>
 
int main(void){
	int i;
	struct utsname myname;
	i = uname(&myname); /* hold the structure */
	if ( i == 0 ){
		printf("Operating system name : %s\n",myname.sysname);
		printf("Node name : %s\n",myname.nodename);
		printf("Operating system release : %s\n",myname.release);
		printf("Operating system name : %s\n",myname.version);
		printf("Hardware identifier : %s\n",myname.machine);
	}
	else {
		 fprintf(stderr,"Oh no. uname(2) failed with %s\n", strerror(errno));
		 exit(1);
	}
	return 0;
}

Task: Compile program

To compile type the command:
$ gcc test.c
OR
$ cc test.c

Task: Execute program to see output

Above command will create a file called a.out. To see output of test.c program type:
$ ./a.out

Task: Compile to specific executable file

You can specify an execuable file name while compiling program itself:
$ gcc -o test test.c
OR
$ cc test.c -o test
OR
$ make test
Now execute the test program to see output of test.c on screen:
$ ./test
Sample outputs:

Fig.01: My test program in action

Fig.01: My test program in action

This entry is 13 of 13 in the Linux GNU/GCC Compilers Tutorial series. Keep reading the rest of the series:
  1. Ubuntu Linux Install GNU GCC Compiler and Development Environment
  2. Debian Linux Install GNU GCC Compiler and Development Environment
  3. CentOS / RHEL 7: Install GCC (C and C++ Compiler) and Development Tools
  4. Download and Install C, C++ Compiler on Red Hat Enterprise Linux 5 (RHEL)
  5. Mac OS X: Install GCC Compiler with Xcode
  6. Where is My Linux GNU C or GCC Compilers Are Installed?
  7. HowTo: Compile And Run a C/C++ Code In Linux
  8. RHEL / CentOS Linux Install Core Development Tools Automake, Gcc (C/C++), Perl, Python & Debuggers
  9. HowTo Compiling C Program And Creating Executable File Under a Linux / UNIX / *BSD
  10. How To Install ncurses Library on a Linux
  11. Linux Find Out What Compilers Are Installed or Available On The System
  12. Linux Find Out GNU gcc Compiler Version Used To Compile Running Kernel
  13. Howto see output of C program in Linux or UNIX
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55 comments… add one
  • ajay May 25, 2007 @ 4:38

    yaa
    you help me a lot
    thnx budy

    • firoz Jul 1, 2010 @ 5:38

      wt is the process to get output in c program

      • Shaik.moulali Jun 26, 2014 @ 9:26

        After written the program in c language
        To Compile that program in turboc click the ALT+F9
        To Run that program in turboc click the CTRL+F9

  • vivek Jun 4, 2007 @ 18:18

    hey man thanks for the instruction…… i can now compile and run c programs……

  • manisha Sep 15, 2007 @ 11:05

    this is realy very nice.thanks to help me.

  • umair Jan 22, 2008 @ 17:50

    i have installed MinGW now pls tell how to write a program and excuate it

  • pinku Jun 2, 2008 @ 10:19

    Hi,
    from your site i came to know how to compile and see out put of program, but how to write c program in linux????I m a window user,so if anyone give me that ans i will be obliged.

    • Harish Kadam Jan 20, 2017 @ 10:23

      Use just have to do write ur program in gedit and save it with c extension…..
      U have to go In file right click then document then click empty document….
      Now u can write ur program this is gedit then save it filename.c extension…..

      Have…fun…..

  • rakesh kumar thakur Aug 15, 2008 @ 5:11

    i search this site through google and find my answer on the topic … How can i run and compile program on gcc compiler?

  • tintin Oct 23, 2008 @ 0:18

    Nice post. It helps newbie a lot.
    :)

  • ashutosh Feb 1, 2009 @ 10:21

    The given commands is work properly…………
    it is very helpful

  • Stefaan Apr 21, 2009 @ 17:19

    Thanx man!!!

  • Thanks for this tip May 8, 2009 @ 10:01

    Thanks for this tip
    Plz also tell me how to enter the out put of one c program to another one plz send this at my email address.
    Thanks for this tip

  • Avinash T M May 21, 2009 @ 12:52

    Superb information , i liked this website very much.

  • bhargav Jul 19, 2009 @ 19:23

    i am executing c program in fedora as gcc temp.c but it says that
    bash: gcc: command not found
    please tell how to run

  • neeraj sinha Jul 28, 2009 @ 14:30

    @bhargav:
    Update your YUM repo (in Fedora/ RHEL), thereafter
    run the following command as root:
    yum install gcc
    or simply write
    sudo yum install gcc
    have fun!

  • Ivneet Aug 17, 2009 @ 6:35

    I am successfully executing a C prg in Turbo C but i am getting a runtime error in gcc. Please help

  • neeraj sinha Aug 18, 2009 @ 16:30

    @Ivneet:
    Please be specific about your program. Paste it anywhere and give us the link.

  • mahavir Sep 15, 2009 @ 1:04

    Awesome man!!!!!\
    this really helped………..

  • Mobashir Sep 26, 2009 @ 19:27

    i m a new user for linux platform,may any body plz let me know how to code,compile etc a graphics application for c++ under linux platform ,,,,,( explain with example plz)

  • vaibhav Oct 7, 2009 @ 13:50

    it is showing that gcc command not found . so what to do help me body.

  • neeraj sinha Oct 7, 2009 @ 20:19

    @vaibhav!
    probably gcc is not installed. Install it first depending on your linux.
    and try the commands. !
    http://susenj.wordpress.com

  • yash Oct 8, 2009 @ 3:14

    i hav c++ program in linux how i ll run it in windows c++ because it gives 25 errors

  • Shivam Oct 21, 2009 @ 14:59

    thx buddy it really helps me….

    their is some IDE for C++ environment…

  • neeraj sinha Oct 22, 2009 @ 3:02

    @shivam:
    yes there is: like KDevelop, Anjuta, Kate etc.

  • soumendu ganguly Dec 6, 2009 @ 3:19

    thanx…….
    u help me lot……….

  • sagnik mukherjee Feb 11, 2010 @ 10:20

    THANK U….:)

  • Hk Apr 27, 2010 @ 9:50

    I use Fedora 12 (live Cd).
    i created a c program in it and tried to execute.
    it says that no such command..
    how to eliminate this problem.
    Thanks

  • kiran May 27, 2010 @ 12:37

    Thanks…

    • firoz Jul 1, 2010 @ 5:40

      how to get o/p in c program pls explain me na

  • www Sep 25, 2010 @ 19:45

    the output command does not do on fedora 13
    #./test

  • hemant Mar 3, 2011 @ 7:20

    i hav c program in linux how i ll run it in windows c because it gives 25 errors

  • mohammed fereja Apr 12, 2011 @ 9:50

    thanks..alot it just helped me out

  • sreedhar.M Apr 19, 2011 @ 10:26

    I am sreedhar,i am doing MCA.I have interest to learn programming languages in linux operating system.so,what should i do.

  • murali Jun 29, 2011 @ 3:52

    thank u

  • David Jul 23, 2011 @ 16:26

    ha, of course. Thanks for posting this. Saved me an embarrassing question on some IRC channel or a forum.

  • Hubert Vijay Sep 13, 2011 @ 22:29

    Good work dude….proves to be very useful for the begginers

  • akshata kittur Oct 2, 2011 @ 16:01

    I have typed a hello world program in fedora.. But how should i get back to the terminal.what are the keys on keyboard that i hav t press and want commands to type so that my file is saved.

    • Harish Kadam Jan 20, 2017 @ 10:26

      Create ur file in edit n save the file with .c extension…..
      Then compile……then run….through commands

  • vandana Dec 13, 2011 @ 5:29

    thnx…..for providin this nice solution…

  • vaishali Mar 30, 2012 @ 4:17

    it really helped me thanks

  • ankit senger Aug 6, 2012 @ 9:34

    thanks it is very helpful for me

  • kishore vignesh Aug 10, 2012 @ 7:57

    thank you :) !

  • lata Sep 11, 2012 @ 4:51

    Is gcc compiler necessary for C++ programming under Linux????
    Can we do this without any compiler????

    • neeraj Sep 11, 2012 @ 10:00

      Any language needs a compiler/interpreter.
      I can even run Turbo C++ on Linux.
      so, answer to your first question = no, but yes, it’s the most preferred compiler for any *nix Operating system.
      for second question = No.

      • lata Sep 11, 2012 @ 11:24

        Neeraj,
        thank you so much for ur help and consideration

  • sra1 Sep 28, 2012 @ 6:55

    thanq nd what abt html programmes

    • neeraj Sep 28, 2012 @ 13:05

      Sorry, There is no programming language called HTML.
      What exactly you want to do with HTML under gcc?

  • sanju Nov 6, 2012 @ 6:56

    hey there, can you tell me how to see the output of a c++ program in unix environment page by page ???

  • Dibya Nov 26, 2012 @ 7:27

    Thank Man…

  • nagababu Nov 28, 2012 @ 6:31

    thanks to this web site

  • George Maithya Jul 8, 2014 @ 14:12

    Please show me how to write a program in c that prints a file a screenfull at a time waiting for response from user.

  • hs Nov 7, 2015 @ 15:50

    thank u ….

  • Precious May 30, 2016 @ 15:47

    How about if i am making use of code block how do i get to see the output on the screen\

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