Manual pages for the C standard library, C POSIX library, and the CS50 Library for those less comfortable.

aio.h

arpa/inet.h

assert.h

complex.h

cs50.h

ctype.h

dirent.h

dlfcn.h

errno.h

fcntl.h

fenv.h

fmtmsg.h

fnmatch.h

ftw.h

glob.h

grp.h

iconv.h

inttypes.h

langinfo.h

libgen.h

limits.h

locale.h

math.h

monetary.h

mqueue.h

net/if.h

netdb.h

netinet/in.h

nl_types.h

poll.h

pthread.h

pwd.h

sched.h

search.h

semaphore.h

setjmp.h

signal.h

spawn.h

stdarg.h

stddef.h

stdio.h

stdlib.h

string.h

strings.h

sys/ipc.h

sys/mman.h

sys/msg.h

sys/select.h

sys/socket.h

sys/stat.h

sys/statvfs.h

sys/time.h

sys/times.h

sys/types.h

sys/uio.h

sys/utsname.h

syslog.h

termios.h

time.h

ulimit.h

unistd.h

utmpx.h

wchar.h

wctype.h

wordexp.h