The POSIX Command Language and Utilities standard for
introduced the following changes into the language:
CONVFMTfor controlling the conversion of numbers to strings (see section Conversion of Strings and Numbers)
In 2012, a number of extensions that had been commonly available for many years were finally added to POSIX. They are:
fflush()built-in function for flushing buffered output (see section Input/Output Functions)
nextfilestatement (see section The
See section Common Extensions Summary for a list of common extensions not permitted by the POSIX standard.
The 2018 POSIX standard can be found online at https://pubs.opengroup.org/onlinepubs/9699919799/.