Tcsh is an enhanced but completely compatible version of the Berkeley UNIX C shell. It is a command language interpreter usable both as an interactive login shell and a shell script command processor. It includes a command line editor, programmable word completion, command and file name completion, listing, spelling correction, a history mechanism, job control, and a bunch of small additions to the csh shell itself.
NSH is a CLI intended for OpenBSD-based network appliances. It replaces ifconfig, sysctl, and route with its own simple command language, and consolidates configuration for other daemons into one place, effectively replacing /etc/netstart and parts of /etc/rc for appliance-style usage. NSH presents the user with a vaguely Cisco-like interface with all configuration in one easy to read text list. It also gives the user access to system information and diagnostics. NSH replaces the userland commands that handle these functions, and talks directly to the OpenBSD kernel or control utility for daemon functionality. Supported external utilities: pf, ospfd, ospf6d, bgpd, ripd, ldpd, relayd, ipsecctl, iked, rtadvd, dvmrpd, sasyncd, dhcpd, snmpd, sshd, ntpd, ifstated, tftp-proxy, ftp-proxy, tftpd, npppd, resolv.conf, inetd, smtpd, ldapd, and ifstated.
optcomplete is a Python module that provides programmable shell completion support for Python scripts that use the optparse module. It implements the Bash completion protocol, and a simple common shell function invokes the script to provide the completion suggestions. As an optparse parser already contains most of the useful information to provide completions, only two lines of code are required to provide basic support for completions to an existing script. It also allows the developer to provide per-option completion, etc.