lhunath 1340023555 learn http://pubs.opengroup.org/onlinepubs/9699919799/utilities/V3_chap02.html#tag_18
emanuele6 1729941794 forget
emanuele6 1729941798 learn https://pubs.opengroup.org/onlinepubs/9799919799/utilities/V3_chap02.html#tag_19