Shell Interactive Shell
shell-command) reads a line of text using the
minibuffer and executes it as a shell command in a subshell made just
for that command. Standard input for the command comes from the null
device. If the shell command produces any output, the output goes into
an Emacs buffer named `
*Shell Command Output*', which is displayed
in another window but not selected. A numeric argument, as in M-1 M-!, directs this command to insert any output into the current buffer.
In that case, point is left before the output and the mark is set after
If the shell command line ends in `
&', it runs asynchronously.
For a synchronous shell command,
shell-command returns the
command's exit status (0 means success), when it is called from a Lisp
shell-command-on-region) is like M-! but
passes the contents of the region as the standard input to the shell
command, instead of no input. If a numeric argument is used, meaning
insert the output in the current buffer, then the old region is deleted
first and the output replaces it as the contents of the region. It
returns the command's exit status when it is called from a Lisp program.
Both M-! and M-| use
shell-file-name to specify the
shell to use. This variable is initialized based on your
environment variable when Emacs is started. If the file name does not
specify a directory, the directories in the list
searched; this list is initialized based on the environment variable
PATH when Emacs is started. Your `
.emacs' file can override
either or both of these default initializations.
Both M-! and M-| wait for the shell command to complete.
To stop waiting, type C-g to quit; that terminates the shell
command with the signal
SIGINT---the same signal that C-c
normally generates in the shell. Emacs waits until the command actually
terminates. If the shell command doesn't stop (because it ignores the
SIGINT signal), type C-g again; this sends the command a
SIGKILL signal which is impossible to ignore.
To specify a coding system for M-! or M-|, use the command
RET c immediately beforehand. See Specify Coding.
Error output from the command is normally intermixed with the regular
output. If you set the variable
shell-command-default-error-buffer to a string, which is a buffer
name, error output is inserted before point in the buffer of that name.