pipe - Piping buffer to external command in Vim

Question

I am kind of a Vim novice. I would like to send contents of the current buffer to stdin of external command (lets say mail). My final purpose is to set a shortcut to quickly send email from current Vim buffer. I am guessing this should be a trivial stuff, but I couldn't find a way to send Vim buffer to an external command. Thanks in advance.

Answer 1

You can use :w !cmd to write the current buffer to the stdin of an external command. From :help :w_c:

                                                        :w_c :write_c
:[range]w[rite] [++opt] !{cmd}
                        Execute {cmd} with [range] lines as standard input
                        (note the space in front of the '!').  {cmd} is
                        executed like with ":!{cmd}", any '!' is replaced with
                        the previous command :!.

A related command is :%!cmd which does the same thing and then replaces the current buffer with the output of the command. So :%!sort would invoke the external sort command to sort the current buffer in place. From :help :range!:

:{range}![!]{filter} [!][arg]                           :range!
                        Filter {range} lines through the external program
                        {filter}.  Vim replaces the optional bangs with the
                        latest given command and appends the optional [arg].
                        Vim saves the output of the filter command in a
                        temporary file and then reads the file into the buffer
                        tempfile.  Vim uses the 'shellredir' option to
                        redirect the filter output to the temporary file.
                        However, if the 'shelltemp' option is off then pipes
                        are used when possible (on Unix).
                        When the 'R' flag is included in 'cpoptions' marks in
                        the filtered lines are deleted, unless the
                        :keepmarks command is used.  Example: 
                                :keepmarks '<,'>!sort
                        When the number of lines after filtering is less than
                        before, marks in the missing lines are deleted anyway.