Question

I am a complete novice with Linux. I have Mint on a laptop and have recently been playing around with it.

I wrote a simple C program and saved the file.
Then in the command line I typed

gcc -c myfile

and out popped a file called a.out. I naively (after years of Windows usage) expected a nice .exe file to appear. I have no idea what to do with this a.out file.

Answer 1

Name it with -o and skip the -c:

gcc -Wall -o somefile myfile

You should name your sourcefiles with a .c extension though.

The typical way of compiling e.g. two source files into an executable:

#Compile (the -c) a file, this produces an object file (file1.o and file2.o)

gcc -Wall -c file1.c
gcc -Wall -c file2.c

#Link the object files, and specify the output name as `myapp` instead of the default `a.out`

gcc -o myapp file1.o file2.o

You can make this into a single step:

gcc -Wall -o myapp file1.c file2.c

Or, for your case with a single source file:

gcc -Wall -o myapp file.c

The -Wall part means “enable (almost) all warnings” – this is a habit you should pick up from the start, it’ll save you a lot of headaches debugging weird problems later.

The a.out name is a leftover from older unixes where it was an executable format. Linkers still name files a.out by default, event though they tend to produce ELF and not a.out format executables now.