emacs: Shell Mode
40.3 Shell Mode
===============
The major mode for Shell buffers is Shell mode. Many of its special
commands are bound to the ‘C-c’ prefix, and resemble the usual editing
and job control characters present in ordinary shells, except that you
must type ‘C-c’ first. Here is a list of Shell mode commands:
‘<RET>’
Send the current line as input to the subshell
(‘comint-send-input’). Any shell prompt at the beginning of the
line is omitted (
Shell Prompts). If point is at the end of
buffer, this is like submitting the command line in an ordinary
interactive shell. However, you can also invoke <RET> elsewhere in
the shell buffer to submit the current line as input.
‘<TAB>’
Complete the command name or file name before point in the shell
buffer (‘completion-at-point’). This uses the usual Emacs
completion rules (Completion), with the completion
alternatives being file names, environment variable names, the
DONTPRINTYET shell command history, and history references (History
References). For options controlling the completion, *noteShell
DONTPRINTYET shell command history, and history references (History
References). For options controlling the completion, Shell
Options.
‘M-?’
Display temporarily a list of the possible completions of the file
name before point (‘comint-dynamic-list-filename-completions’).
‘C-d’
Either delete a character or send EOF
(‘comint-delchar-or-maybe-eof’). Typed at the end of the shell
buffer, this sends EOF to the subshell. Typed at any other
position in the buffer, this deletes a character as usual.
‘C-c C-a’
Move to the beginning of the line, but after the prompt if any
(‘comint-bol-or-process-mark’). If you repeat this command twice
in a row, the second time it moves back to the process mark, which
is the beginning of the input that you have not yet sent to the
subshell. (Normally that is the same place—the end of the prompt
on this line—but after ‘C-c <SPC>’ the process mark may be in a
previous line.)
‘C-c <SPC>’
Accumulate multiple lines of input, then send them together. This
command inserts a newline before point, but does not send the
preceding text as input to the subshell—at least, not yet. Both
lines, the one before this newline and the one after, will be sent
together (along with the newline that separates them), when you
type <RET>.
‘C-c C-u’
Kill all text pending at end of buffer to be sent as input
(‘comint-kill-input’). If point is not at end of buffer, this only
kills the part of this text that precedes point.
‘C-c C-w’
Kill a word before point (‘backward-kill-word’).
‘C-c C-c’
Interrupt the shell or its current subjob if any
(‘comint-interrupt-subjob’). This command also kills any shell
input pending in the shell buffer and not yet sent.
‘C-c C-z’
Stop the shell or its current subjob if any (‘comint-stop-subjob’).
This command also kills any shell input pending in the shell buffer
and not yet sent.
‘C-c C-\’
Send quit signal to the shell or its current subjob if any
(‘comint-quit-subjob’). This command also kills any shell input
pending in the shell buffer and not yet sent.
‘C-c C-o’
Delete the last batch of output from a shell command
(‘comint-delete-output’). This is useful if a shell command spews
out lots of output that just gets in the way.
‘C-c C-s’
Write the last batch of output from a shell command to a file
(‘comint-write-output’). With a prefix argument, the file is
appended to instead. Any prompt at the end of the output is not
written.
‘C-c C-r’
‘C-M-l’
Scroll to display the beginning of the last batch of output at the
top of the window; also move the cursor there
(‘comint-show-output’).
‘C-c C-e’
Scroll to put the end of the buffer at the bottom of the window
(‘comint-show-maximum-output’).
‘C-c C-f’
Move forward across one shell command, but not beyond the current
line (‘shell-forward-command’). The variable
‘shell-command-regexp’ specifies how to recognize the end of a
command.
‘C-c C-b’
Move backward across one shell command, but not beyond the current
line (‘shell-backward-command’).
‘M-x dirs’
Ask the shell for its working directory, and update the Shell
buffer’s default directory. Directory Tracking.
‘M-x send-invisible <RET> TEXT <RET>’
Send TEXT as input to the shell, after reading it without echoing.
This is useful when a shell command runs a program that asks for a
password.
Please note that Emacs will not echo passwords by default. If you
really want them to be echoed, evaluate (Lisp Eval) the
following Lisp expression:
(remove-hook 'comint-output-filter-functions
'comint-watch-for-password-prompt)
‘M-x comint-continue-subjob’
Continue the shell process. This is useful if you accidentally
suspend the shell process.(1)
‘M-x comint-strip-ctrl-m’
Discard all control-M characters from the current group of shell
output. The most convenient way to use this command is to make it
run automatically when you get output from the subshell. To do
that, evaluate this Lisp expression:
(add-hook 'comint-output-filter-functions
'comint-strip-ctrl-m)
‘M-x comint-truncate-buffer’
This command truncates the shell buffer to a certain maximum number
of lines, specified by the variable ‘comint-buffer-maximum-size’.
Here’s how to do this automatically each time you get output from
the subshell:
(add-hook 'comint-output-filter-functions
'comint-truncate-buffer)
Shell mode is a derivative of Comint mode, a general-purpose mode for
communicating with interactive subprocesses. Most of the features of
Shell mode actually come from Comint mode, as you can see from the
command names listed above. The special features of Shell mode include
the directory tracking feature, and a few user commands.
Other Emacs features that use variants of Comint mode include GUD
(Debuggers) and ‘M-x run-lisp’ (External Lisp).
You can use ‘M-x comint-run’ to execute any program of your choice in
a subprocess using unmodified Comint mode—without the specializations of
Shell mode.
---------- Footnotes ----------
(1) You should not suspend the shell process. Suspending a subjob of
the shell is a completely different matter—that is normal practice, but
you must use the shell to continue the subjob; this command won’t do it.
Info Catalog
emacs: Interactive Shell
emacs: Shell
emacs: Shell Prompts