There are a number of different standards that specify the behavior of portable programs in a Unix-like environment. POSIX 1003.2 and XPG4 are two of the more widely known ones. Where the behavior specified by a standard differs from the historical behavior provided by a command, Solaris provides a different version of the command in /usr/xpg4/bin. These commands are listed here, but not otherwise covered in this book, as most users typically do not have /usr/xpg4/bin in their search paths. The manual entries for each command discuss the differences between the /usr/bin version and the /usr/xpg4/bin version.
