How do I use /etc/export.d/?

How do I use /etc/export.d/ to export filesystems?

I am attempting to export an sge cell's configuration via nfs. However, the export does not appear to work.

# cat /etc/exports.d/sge-example.com
/opt/sge/example.com 192.0.2.0/24(ro)
# exportfs -rv
exportfs: No file systems exported!
# strace exportfs -rv 2>&1
execve("/usr/sbin/exportfs", ["exportfs", "-rv"], [/* 27 vars */]) = 0
brk(NULL)                               = 0x55d9bfde2000
mmap(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x7fb67e9e0000
access("/etc/ld.so.preload", R_OK)      = -1 ENOENT (No such file or directory)
open("/etc/ld.so.cache", O_RDONLY|O_CLOEXEC) = 3
fstat(3, {st_mode=S_IFREG|0644, st_size=28419, ...}) = 0
mmap(NULL, 28419, PROT_READ, MAP_PRIVATE, 3, 0) = 0x7fb67e9d9000
close(3)                                = 0
open("/lib64/libwrap.so.0", O_RDONLY|O_CLOEXEC) = 3
read(3, "\177ELF\2\1\1\0\0\0\0\0\0\0\0\0\3\0>\0\1\0\0\0\3403\0\0\0\0\0\0"..., 832) = 832
fstat(3, {st_mode=S_IFREG|0755, st_size=42520, ...}) = 0
mmap(NULL, 2138208, PROT_READ|PROT_EXEC, MAP_PRIVATE|MAP_DENYWRITE, 3, 0) = 0x7fb67e5b5000
mprotect(0x7fb67e5be000, 2093056, PROT_NONE) = 0
mmap(0x7fb67e7bd000, 8192, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_DENYWRITE, 3, 0x8000) = 0x7fb67e7bd000
mmap(0x7fb67e7bf000, 96, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_ANONYMOUS, -1, 0) = 0x7fb67e7bf000
close(3)                                = 0
open("/lib64/libc.so.6", O_RDONLY|O_CLOEXEC) = 3
read(3, "\177ELF\2\1\1\3\0\0\0\0\0\0\0\0\3\0>\0\1\0\0\0\20\35\2\0\0\0\0\0"..., 832) = 832
fstat(3, {st_mode=S_IFREG|0755, st_size=2127336, ...}) = 0
mmap(NULL, 3940800, PROT_READ|PROT_EXEC, MAP_PRIVATE|MAP_DENYWRITE, 3, 0) = 0x7fb67e1f2000
mprotect(0x7fb67e3aa000, 2097152, PROT_NONE) = 0
mmap(0x7fb67e5aa000, 24576, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_DENYWRITE, 3, 0x1b8000) = 0x7fb67e5aa000
mmap(0x7fb67e5b0000, 16832, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_ANONYMOUS, -1, 0) = 0x7fb67e5b0000
close(3)                                = 0
open("/lib64/libnsl.so.1", O_RDONLY|O_CLOEXEC) = 3
read(3, "\177ELF\2\1\1\0\0\0\0\0\0\0\0\0\3\0>\0\1\0\0\0\240@\0\0\0\0\0\0"..., 832) = 832
fstat(3, {st_mode=S_IFREG|0755, st_size=113584, ...}) = 0
mmap(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x7fb67e9d8000
mmap(NULL, 2198200, PROT_READ|PROT_EXEC, MAP_PRIVATE|MAP_DENYWRITE, 3, 0) = 0x7fb67dfd9000
mprotect(0x7fb67dfef000, 2093056, PROT_NONE) = 0
mmap(0x7fb67e1ee000, 8192, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_DENYWRITE, 3, 0x15000) = 0x7fb67e1ee000
mmap(0x7fb67e1f0000, 6840, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_ANONYMOUS, -1, 0) = 0x7fb67e1f0000
close(3)                                = 0
mmap(NULL, 8192, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x7fb67e9d6000
arch_prctl(ARCH_SET_FS, 0x7fb67e9d6740) = 0
mprotect(0x7fb67e5aa000, 16384, PROT_READ) = 0
mprotect(0x7fb67e1ee000, 4096, PROT_READ) = 0
mprotect(0x7fb67e7bd000, 4096, PROT_READ) = 0
stat("/etc/sysconfig/64bit_strstr_via_64bit_strstr_sse2_unaligned", 0x7ffffa926630) = -1 ENOENT (No such file or directory)
mprotect(0x55d9be0a5000, 4096, PROT_READ) = 0
mprotect(0x7fb67e9e1000, 4096, PROT_READ) = 0
munmap(0x7fb67e9d9000, 28419)           = 0
getpid()                                = 12763
rt_sigaction(SIGUSR1, {0x55d9bde9d580, [USR1], SA_RESTORER|SA_RESTART, 0x7fb67e227270}, {SIG_DFL, [], 0}, 8) = 0
rt_sigaction(SIGUSR2, {0x55d9bde9d580, [USR2], SA_RESTORER|SA_RESTART, 0x7fb67e227270}, {SIG_DFL, [], 0}, 8) = 0
stat("/etc/nfs.conf", {st_mode=S_IFREG|0644, st_size=953, ...}) = 0
open("/etc/nfs.conf", O_RDONLY)         = 3
brk(NULL)                               = 0x55d9bfde2000
brk(0x55d9bfe03000)                     = 0x55d9bfe03000
brk(NULL)                               = 0x55d9bfe03000
read(3, "#\n# This is a general conifgurat"..., 953) = 953
close(3)                                = 0
access("/proc/fs/nfs/filehandle", F_OK) = -1 ENOENT (No such file or directory)
access("/proc/fs/nfsd/filehandle", F_OK) = 0
open("/var/lib/nfs/export-lock", O_RDWR|O_CREAT, 0666) = 3
fcntl(3, F_SETLKW, {l_type=F_WRLCK, l_whence=SEEK_CUR, l_start=0, l_len=0}) = 0
open("/etc/exports", O_RDONLY)          = 4
fstat(4, {st_mode=S_IFREG|0644, st_size=0, ...}) = 0
mmap(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x7fb67e9df000
read(4, "", 4096)                       = 0
read(4, "", 4096)                       = 0
close(4)                                = 0
munmap(0x7fb67e9df000, 4096)            = 0
openat(AT_FDCWD, "/etc/exports.d", O_RDONLY|O_NONBLOCK|O_DIRECTORY|O_CLOEXEC) = 4
getdents(4, /* 3 entries */, 32768)     = 72
getdents(4, /* 0 entries */, 32768)     = 0
close(4)                                = 0
write(2, "exportfs: ", 10exportfs: )              = 10
write(2, "No file systems exported!", 25No file systems exported!) = 25
write(2, "\n", 1
)                       = 1
open("/var/lib/nfs/.etab.lock", O_RDWR|O_CREAT, 0600) = 4
fcntl(4, F_SETLKW, {l_type=F_WRLCK, l_whence=SEEK_SET, l_start=0, l_len=0}) = 0
open("/var/lib/nfs/etab.tmp", O_WRONLY|O_CREAT|O_TRUNC, 0666) = 5
close(5)                                = 0
open("/var/lib/nfs/etab.tmp", O_RDONLY) = 5
open("/var/lib/nfs/etab", O_RDONLY)     = 6
read(5, "", 4096)                       = 0
read(6, "", 4096)                       = 0
close(5)                                = 0
close(6)                                = 0
unlink("/var/lib/nfs/etab.tmp")         = 0
close(4)                                = 0
stat("/var/lib/nfs/etab", {st_mode=S_IFREG|0644, st_size=0, ...}) = 0
open("/proc/net/rpc/auth.unix.ip/flush", O_RDWR) = 4
write(4, "1525480721\n", 11)            = 11
close(4)                                = 0
open("/proc/net/rpc/auth.unix.gid/flush", O_RDWR) = 4
write(4, "1525480721\n", 11)            = 11
close(4)                                = 0
open("/proc/net/rpc/nfsd.fh/flush", O_RDWR) = 4
write(4, "1525480721\n", 11)            = 11
close(4)                                = 0
open("/proc/net/rpc/nfsd.export/flush", O_RDWR) = 4
write(4, "1525480721\n", 11)            = 11
close(4)                                = 0
fcntl(3, F_SETLK, {l_type=F_UNLCK, l_whence=SEEK_CUR, l_start=0, l_len=0}) = 0
exit_group(0)                           = ?
+++ exited with 0 +++

The same issue does not occur if I include the same line directly in /etc/exports.