ERRNO (man3p)
errno — error return value
errno — error return value
fputws — put a wide-character string on a stream
ftell, ftello — return a file offset in a stream
rename, renameat — rename file
cos, cosf, cosl — cosine function
logf, logl — natural logarithm function
ttyname, ttyname_r — find the pathname of a terminal
lsearch, lfind — linear search and update
ceil, ceilf, ceill — ceiling value function
sysconf — get configurable system variables