FTRYLOCKFILE (man3p)
ftrylockfile — stdio locking functions
ftrylockfile — stdio locking functions
getline — read a delimited record from stream
freopen — open a stream
openlog — open a connection to the logging facility
getsid — get the process group ID of a session leader
cosh, coshf, coshl — hyperbolic cosine functions
posix_trace_open, posix_trace_rewind — trace log management (TRACING)
pthread_rwlockattr_destroy, pthread_rwlockattr_init — destroy and initialize the read-write lock attributes object
getrusage — get information about resource utilization
sigaddset — add a signal to a signal set