sh - command interpreter (shell)
sh [-/+aCeflnuvxIimsVEb] [-/+o longname] [arg ...]
The sh(1) utility is the standard command interpreter for the system. The file /bin/sh is a copy of the Korn Shell, ksh(1). For full POSIX conformance, invoke with the option -o posix.
The Korn Shell is described in ksh(1). The effects of setting POSIX mode (and the defaults) are described in the section POSIX Mode.
ksh(1)