Try these shell commands at the prompt. Many of commands have extensive additional arguments they can take.
Display the value of the $SHELL environment variable, which stores the pathname of the current shell.
$ echo $SHELL /bin/bash
List the available shells in the system. cat (concatenate) is a standard Linux utilities that concatenates and prints the content of a file to standard output. shells is the name of the file, and /etc/ is the pathname of the directory where this file is stored.
$ cat /etc/shells /bin/sh /bin/bash /sbin/nologin /bin/tcsh /bin/csh /bin/ksh /bin/zsh /usr/bin/tmux
Find the current date and time with the date command.
$ date Thu Apr 18 09:52:18 CDT 2013
List all of your own current running processes with the ps command (process status). In Linux, each process is associated with a process identification (PID).
$ ps PID TTY TIME CMD 916 pts/58 00:00:00 bash 1531 pts/58 00:00:00 ps