How to compile and run C program on Mac OS X

Question

I am learning C and wish to write the program using a text editor on my Mac (running OS X v10.7 (Lion)).

I write the .c file, and compile it using gcc filename.c - which creates executable file called a.out. However, when I type a.out or /a.out, I get the following messages:

-bash: a.out: command not foundor-bash: /a.out:
No such file or directory

I have successfully compiled and ran C programs on Linux systems before using this same method. What am I doing wrong on my Mac?

The canonical question is *[How can I compile and run C/C++ code in a Unix console or Mac terminal?](https://stackoverflow.com/questions/221185/)*. — Peter Mortensen, May 08 '22 at 13:45

score 56 · Accepted Answer · answered Dec 15 '12 at 00:01

56

You need to add a dot to indicate that the executable is in the current directory, as the current directory is not in the path:

./a.out

answered Dec 15 '12 at 00:01

MByD

133,244
25
260
270

3

@JTWheeler, you might also consider naming your object file as this would prevent a.out from being overwritten when compiling multiple C programs manually in the same directory. Do `gcc myprog1.c -o myprog1.o` and run it by doing `./myprog1.o`. Just a suggestion. And alternatively you could use clang instead of gcc for you practice code as it gives better error details. – Bharat Dec 15 '12 at 00:08

score 17 · Answer 2 · edited Sep 23 '21 at 21:24

17

You need to precede a.out with ./ as follows:

./a.out

Additionally, you may find it useful to change the name of the resultant executable. Example:

gcc nameofprogramyouwrote.c -o whatyouwanttheprogramtobenamed

...then execute it like this:

./whatyouwanttheprogramtobenamed

edited Sep 23 '21 at 21:24

user664833

16,967
18
88
129

answered Nov 23 '13 at 05:47

beckah

1,482
5
26
57

score 5 · Answer 3 · answered Dec 15 '12 at 00:03

You have to add a dot in front of the slash:

./a.out

/a.out would try to execute a program in the root folder (/).
a.out will look for your program in all the folders defined in the PATH environment variable.

I have successfully compiled and ran C programs on Linux systems before using this same method. What am I doing wrong on my Mac?

You have to do the same on Linux.

score 4 · Answer 4 · answered Jan 26 '17 at 20:23

4

To build:

    gcc -Wall -o yourFile yourFile.c

Then to execute:

    ./yourFile

answered Jan 26 '17 at 20:23

aFactoria

817
1
7
7

always wondered for generating an executable with the name of C file. +1 – Priyank Thakkar Jun 30 '18 at 23:23

score 3 · Answer 5 · edited May 10 '22 at 21:30

3

Make sure to set your permissions executable with chmod +x a.out.

edited May 10 '22 at 21:30

Peter Mortensen

30,030
21
100
124

answered Dec 15 '12 at 00:03

MichaelM

477
1
5
16

5

gcc does it for you... Do not need to run chmod – benjarobin Dec 15 '12 at 00:10
1

Correct, but this is good practice as not everyone is using gcc. – MichaelM Dec 15 '12 at 00:27
Is this any different from `chmod 777 a.out`? – Lucas Jun 11 '20 at 13:03
Yes, chmod 777 will make executable, readable, writable, deletable for everyone with access on the system. – MichaelM Jun 12 '20 at 14:07
[chmod 777](https://chmodcommand.com/chmod-777/). [chmod 755](https://chmodcommand.com/chmod-755/) or [chmod 744](https://chmodcommand.com/chmod-744/) may be closer, but `u+x` is better – Peter Mortensen May 10 '22 at 21:37

score -1 · Answer 6 · edited May 10 '22 at 21:40

-1

You'll need a compiler. The easiest way, however, is to install Xcode. This way you'll get access to GCC.

Thus,

gcc -o mybinaryfile mysourcefile.c

Then run it like this.

./mybinaryfile

edited May 10 '22 at 21:40

Peter Mortensen

30,030
21
100
124

answered Dec 26 '16 at 04:00

Kent Aguilar

4,420
1
31
20

How to compile and run C program on Mac OS X

6 Answers6