Dash

The Debian Almquist Shell. Dash is the default /bin/sh on Debian-family distributions and is built for script execution speed, not interactive use. Stock dash links against the kernel read() syscall directly and does not include a line editor: no readline, no history, no completion, no Ctrl-r. What the operator sees at an interactive dash prompt is whatever the terminal driver provides.

For a comfortable interactive shell, use bash, zsh, or fish. Reach for dash when measuring script-start overhead, validating POSIX-only behaviour, or running on an embedded target where size matters.

Terminal Driver

The terminal driver (stty) provides the only line editing dash sees. These are POSIX special characters, set per-terminal and overridable with stty <name> <key>. stty -a prints every current setting.

Key	Action
Backspace (erase)	erase the previous character on the current line
Ctrl-u (kill)	erase the whole line (terminal-driver erase, not a shell widget)
Ctrl-w (werase)	erase the previous word (whitespace-delimited)
Ctrl-c (intr)	send SIGINT to the foreground process
Ctrl-\ (quit)	send SIGQUIT to the foreground process (core dump)
Ctrl-z (susp)	send SIGTSTP (suspend) to the foreground process
Ctrl-d (eof)	send EOF; on an empty line, exits the shell
Ctrl-s (stop)	pause terminal output (XOFF)
Ctrl-q (start)	resume terminal output (XON)
Ctrl-r (rprnt)	reprint the current line (terminal driver, not history)
Ctrl-v (lnext)	take the next character literally (escape control characters)

What Does NOT Work

Reflexes from bash / zsh that produce no result in interactive dash.

Key	Result in dash
Up / Down	prints raw escape sequence (^[[A) into the input
Left / Right	prints raw escape sequence; cursor does not move
Tab	inserts a literal tab character
Ctrl-r	reprints the line (terminal driver), no history search
Ctrl-a / Ctrl-e	inserted as raw control characters
Alt-<key>	inserted as Esc + key
!! / !$	no history expansion (POSIX history is opt-in; dash has none)

Workarounds

To make dash usable interactively, wrap it in a line-editor front-end.

Command	Action
rlwrap dash	readline-style editing and per-program history
rlwrap -H ~/.dash_history dash	persistent history file
rlwrap -c dash	filename completion on Tab
socat readline exec:dash	similar wrapper via socat
ledit dash	lightweight line-editor wrapper (less common)
stty -a	print every terminal-driver setting
stty erase '^H'	set Backspace to send Ctrl-H
stty werase '^W'	set the word-erase character
stty sane	reset all settings to defaults after a stuck terminal

References

• man 1 dash, man 1p sh (POSIX shell).

• man 1 stty, man 7 termios (the terminal driver underneath every shell).

• Dash for /bin/sh usage details.