I think you might have missed the joke. The point is that cat is not an editor; it's simply a way of getting the text into the file in one go, with no editing or correcting. You write it once, and that's it.
If you're getting at something else, can you be clearer?
$ cat > hello.c
#include <stdio.h>
main(void) {
printf("Hello, world.\n");
}
^D
$ gcc hello.c
$ ./a.out
Hello, world.
The joke is that you don't edit, you just use cat and perhaps (if you were going to be obtuse)... echo. For example:
echo "#stdio.h\n int main(int argc, char **argv){\nprintf(\"hello World\\n\");\nreturn(0);\n}" > helloworld.c
then
cat helloworld.c
repeat.
(also, I must be bored to go and type that out)
Nah, echo is clearly better:
echo 'main(){puts("Hello world\n");}' | gcc -xc -
Even if you want to use cat (felines are after all wonderful), why bother putting the source to disk? Just redirect cat's output to the compiler, as in the echo case.
Lets see how far we can take this.
the output to all of these will be:
Hello World
$ perl -E"$(cat)"
say 'Hello World'
^D
$ test=$(cat); perl -E"$test"
say 'Hello World'
^D
$ cat | perl -M5.010
say 'Hello World'
^D
$ cat > test; test=$(cat test); perl -E"$test"
say 'Hello World'
^D
$ cat > test; test=$(cat test)$(cat); perl -E"$test"
say
^D
'Hello World'
^D
$ cat > test; test=$(cat test); perl -E"$test$(cat)"
say
^D
'Hello World'
^D
$ cat > test; test=$(cat test); perl -E"$(cat)$test"
'Hello World'
^D
gcc? real programmers use cat and xxd:
$ cat | xxd -r > a.out
0000000: cefa edfe 0700 0000 0300 0000 0200 0000 ................
0000010: 0b00 0000 a803 0000 8500 0000 0100 0000 ................
0000020: 3800 0000 5f5f 5041 4745 5a45 524f 0000 8...__PAGEZERO..
0000030: 0000 0000 0000 0000 0010 0000 0000 0000 ................
<lot of other stuff>
0003090: 0a00 0000 0b00 0000 2000 6479 6c64 5f73 ........ .dyld_s
00030a0: 7475 625f 6269 6e64 696e 675f 6865 6c70 tub_binding_help
00030b0: 6572 005f 5f64 796c 645f 6675 6e63 5f6c er.__dyld_func_l
00030c0: 6f6f 6b75 7000 6479 6c64 5f5f 6d61 6368 ookup.dyld__mach
00030d0: 5f68 6561 6465 7200 5f4e 5841 7267 6300 _header._NXArgc.
00030e0: 5f4e 5841 7267 7600 5f5f 5f70 726f 676e _NXArgv.___progn
00030f0: 616d 6500 5f5f 6d68 5f65 7865 6375 7465 ame.__mh_execute
0003100: 5f68 6561 6465 7200 5f65 6e76 6972 6f6e _header._environ
0003110: 005f 6d61 696e 0073 7461 7274 005f 6578 ._main.start._ex
0003120: 6974 005f 7075 7473 0000 0000 it._puts....
^D
$ chmod 755 ./a.out
$ ./a.out
Hello, world.
btw, I didn't know that 0xFEEDFACE was the magic number in Mach-O binaries... cool.
See Wikipedia article on Real Programmers. You can find tutorials on the web. Best to know assembly first (know it very well).
"Real Programmers don't use IDEs, they write programs using cat > a.out" (that is, they write machine-readable binary files from beginning to end without making any mistakes).
I've stolen the accepted and most voted answer and combined it with the echo answer, but I have added automatic conditional execution if compilation was success.
$ cat | gcc -xc - && ./a.out
#include <stdio.h>
main(void) {
printf("Hello, world.\n");
}
^D
Hello, world.