The echo command echoes its arguments separated by blanks and terminated by a new line on the standard output.
The /user/bin/sh version understands the following C-like escape sequences:
\c print line without newline
\r carriage return
\v vertical tab
\n where n is the 8 bit character whose ASCII code is the 1,2or 3 digit octal number representing that character.
The following option is available to /usr/bin/sh users only if /usr/ucb preceeds /usr/bin in the user's path.It is available to /usr/csh users regardless of the PATH:
-n Do not add newline to the output
The echo command is useful for producing diagnostics in command files, for sending known data into a pipe, and for displaying the contents of environment variables.
The next command will be bc which is an arbitrary-precision arithmetic language in unix