$ ls -l echo*
-rw-r--r--    1 djoyce   users         263 Jan 17  2002 echo1.c
-rw-r--r--    1 djoyce   users         187 Jan 17  2002 echo2.c
-rw-r--r--    1 djoyce   users         191 Jan 17  2002 echo3.c
-rw-r--r--    1 djoyce   users         267 Jan 17  2002 echo4.c
$ gcc echo1.c
$ mv a.out echo1
$ ls -l echo*
-rwx------    1 djoyce   users        4932 Feb  3 13:55 echo1
-rw-r--r--    1 djoyce   users         263 Jan 17  2002 echo1.c
-rw-r--r--    1 djoyce   users         187 Jan 17  2002 echo2.c
-rw-r--r--    1 djoyce   users         191 Jan 17  2002 echo3.c
-rw-r--r--    1 djoyce   users         267 Jan 17  2002 echo4.c
$ echo1 So, how are things, anyway?
So, how are things, anyway?
$ gcc echo2.c -o echo2
$ ls -l echo*
-rwx------    1 djoyce   users        4932 Feb  3 13:55 echo1
-rw-r--r--    1 djoyce   users         263 Jan 17  2002 echo1.c
-rwx------    1 djoyce   users        4875 Feb  3 13:57 echo2
-rw-r--r--    1 djoyce   users         187 Jan 17  2002 echo2.c
-rw-r--r--    1 djoyce   users         191 Jan 17  2002 echo3.c
-rw-r--r--    1 djoyce   users         267 Jan 17  2002 echo4.c
$ echo2 They are fine.  Why do you ask?
They are fine. Why do you ask?
$ gcc echo3.c -o echo3
$ gcc echo4.c -o echo4
$ echo3 Tra-la-la boom de ay.
Tra-la-la boom de ay.
$ echo4 Tra-la-la boom de ay!
Tra-la-la boom de ay!
$