Execute string COMMAND in inferior shell with region as input.
Normally display output (if any) in temp buffer `*Shell Command Output*';
Prefix arg means replace the region with it. Return the exit code of
COMMAND.
To specify a coding system for converting non-ASCII characters
in the input and output to the shell command, use C-x RET c
before this command. By default, the input (from the current buffer)
is encoded using coding-system specified by `process-coding-system-alist',
falling back to `default-process-coding-system' if no match for COMMAND
is found in `process-coding-system-alist'.
Noninteractive callers can specify coding systems by binding
`coding-system-for-read' and `coding-system-for-write'.
If the command generates output, the output may be displayed
in the echo area or in a buffer.
If the output is short enough to display in the echo area
(determined by the variable `max-mini-window-height' if
`resize-mini-windows' is non-nil), it is shown there.
Otherwise it is displayed in the buffer `*Shell Command Output*'.
The output is available in that buffer in both cases.
If there is output and an error, a message about the error
appears at the end of the output. If there is no output, or if
output is inserted in the current buffer, the buffer `*Shell
Command Output*' is deleted.
Optional fourth arg OUTPUT-BUFFER specifies where to put the
command's output. If the value is a buffer or buffer name, put
the output there. Any other value, including nil, means to
insert the output in the current buffer. In either case, the
output is inserted after point (leaving mark after it).
Optional fifth arg REPLACE, if non-nil, means to insert the
output in place of text from START to END, putting point and mark
around it.
Optional sixth arg ERROR-BUFFER, if non-nil, specifies a buffer
or buffer name to which to direct the command's standard error
output. If nil, error output is mingled with regular output.
When called interactively, `shell-command-default-error-buffer'
is used for ERROR-BUFFER.
Optional seventh arg DISPLAY-ERROR-BUFFER, if non-nil, means to
display the error buffer if there were any errors. When called
interactively, this is t.