e/Unistd.h

Information
has gloss	eng: In the C and C++ programming languages, unistd.h is the name of the header file that provides access to the POSIX operating system API. It is defined by the POSIX.1 standard, the base of the Single Unix Specification, and should therefore be available in any conforming (or quasi-conforming) operating system/compiler (all official versions of Unix, including Mac OS X, Linux, etc.).
lexicalization	eng: unistd.h
instance of	e/Header file