2 # For a description of the syntax of this configuration file,
3 # see scripts/kbuild/config-language.txt.
15 Tha 'ash' shell adds about 60k in the default configuration and is
16 the most complete and most pedantically correct shell included with
17 busybox. This shell is actually a derivative of the Debian 'dash'
18 shell (by Herbert Xu), which was created by porting the 'ash' shell
19 (written by Kenneth Almquist) from NetBSD.
21 config ASH_BASH_COMPAT
22 bool "bash-compatible extensions"
26 Enable bash-compatible extensions.
28 config ASH_JOB_CONTROL
33 Enable job control in the ash shell.
40 Enable alias support in the ash shell.
43 bool "Builtin getopt to parse positional parameters"
47 Enable getopts builtin in the ash shell.
49 config ASH_BUILTIN_ECHO
50 bool "Builtin version of 'echo'"
54 Enable support for echo, builtin to ash.
56 config ASH_BUILTIN_PRINTF
57 bool "Builtin version of 'printf'"
61 Enable support for printf, builtin to ash.
63 config ASH_BUILTIN_TEST
64 bool "Builtin version of 'test'"
68 Enable support for test, builtin to ash.
71 bool "'command' command to override shell builtins"
75 Enable support for the ash 'command' builtin, which allows
76 you to run the specified command with the specified arguments,
77 even when there is an ash builtin command with the same name.
80 bool "Check for new mail on interactive shells"
84 Enable "check for new mail" in the ash shell.
86 config ASH_OPTIMIZE_FOR_SIZE
87 bool "Optimize for size instead of speed"
91 Compile ash for reduced size at the price of speed.
93 config ASH_RANDOM_SUPPORT
94 bool "Pseudorandom generator and $RANDOM variable"
98 Enable pseudorandom generator and dynamic variable "$RANDOM".
99 Each read of "$RANDOM" will generate a new pseudorandom value.
100 You can reset the generator by using a specified start value.
101 After "unset RANDOM" the generator will switch off and this
102 variable will no longer have special treatment.
104 config ASH_EXPAND_PRMT
105 bool "Expand prompt string"
109 "PS#" may contain volatile content, such as backquote commands.
110 This option recreates the prompt string from the environment
111 variable each time it is displayed.
117 hush is a small shell (22k). It handles the normal flow control
118 constructs such as if/then/elif/else/fi, for/in/do/done, while loops,
119 case/esac. Redirections, here documents, $((arithmetic))
120 and functions are supported.
122 It will compile and work on no-mmu systems.
124 It does not handle select, aliases, brace expansion,
125 tilde expansion, &>file and >&file redirection of stdout+stderr.
127 config HUSH_BASH_COMPAT
128 bool "bash-compatible extensions"
132 Enable bash-compatible extensions.
139 Enable help builtin in hush. Code size + ~1 kbyte.
141 config HUSH_INTERACTIVE
142 bool "Interactive mode"
146 Enable interactive mode (prompt and command editing).
147 Without this, hush simply reads and executes commands
148 from stdin just like a shell script from a file.
149 No prompt, no PS1/PS2 magic shell variables.
154 depends on HUSH_INTERACTIVE
156 Enable job control: Ctrl-Z backgrounds, Ctrl-C interrupts current
157 command (not entire shell), fg/bg builtins work. Without this option,
158 "cmd &" still works by simply spawning a process and immediately
159 prompting for next command (or executing next command in a script),
160 but no separate process group is formed.
163 bool "Process substitution"
167 Enable process substitution `command` and $(command) in hush.
170 bool "Support if/then/elif/else/fi"
174 Enable if/then/elif/else/fi in hush.
177 bool "Support for, while and until loops"
181 Enable for, while and until loops in hush.
184 bool "Support case ... esac statement"
188 Enable case ... esac statement in hush. +400 bytes.
190 config HUSH_FUNCTIONS
191 bool "Support funcname() { commands; } syntax"
195 Enable support for shell functions in hush. +800 bytes.
198 bool "Support local builtin"
200 depends on HUSH_FUNCTIONS
202 Enable support for local variables in functions.
205 bool "Support export '-n' option"
209 Enable support for export '-n' option in hush. It is a bash extension.
211 config HUSH_RANDOM_SUPPORT
212 bool "Pseudorandom generator and $RANDOM variable"
216 Enable pseudorandom generator and dynamic variable "$RANDOM".
217 Each read of "$RANDOM" will generate a new pseudorandom value.
221 prompt "Choose which shell is aliased to 'sh' name"
222 default FEATURE_SH_IS_ASH
224 Choose which shell you want to be executed by 'sh' alias.
225 The ash shell is the most bash compatible and full featured one.
227 # note: cannot use "select ASH" here, it breaks "make allnoconfig"
228 config FEATURE_SH_IS_ASH
233 config FEATURE_SH_IS_HUSH
237 config FEATURE_SH_IS_NONE
243 prompt "Choose which shell is aliased to 'bash' name"
244 default FEATURE_BASH_IS_NONE
246 Choose which shell you want to be executed by 'bash' alias.
247 The ash shell is the most bash compatible and full featured one.
249 Note that selecting this option does not switch on any bash
250 compatibility code. It merely makes it possible to install
251 /bin/bash (sym)link and run scripts which start with
254 Many systems use it in scripts which use bash-specific features,
255 even simple ones like $RANDOM. Without this option, busybox
256 can't be used for running them because it won't recongnize
257 "bash" as a supported applet name.
259 config FEATURE_BASH_IS_ASH
264 config FEATURE_BASH_IS_HUSH
268 config FEATURE_BASH_IS_NONE
275 bool "lash (deprecated: aliased to hush)"
279 lash is deprecated and will be removed, please migrate to hush.
282 bool "msh (deprecated: please use hush)"
286 msh is deprecated and will be removed, please migrate to hush.
287 If there is a feature msh has but hush does not, please let us know.
289 # The minix shell (adds just 30k) is quite complete and handles things
290 # like for/do/done, case/esac and all the things you expect a Bourne
291 # shell to do. It is not always pedantically correct about Bourne
292 # shell grammar (try running the shell testscript "tests/sh.testcases"
293 # on it and compare vs bash) but for most things it works quite well.
294 # It uses only vfork, so it can be used on uClinux systems.
297 config SH_MATH_SUPPORT
298 bool "POSIX math support"
300 depends on ASH || HUSH
302 Enable math support in the shell via $((...)) syntax.
304 config SH_MATH_SUPPORT_64
305 bool "Extend POSIX math support to 64 bit"
307 depends on SH_MATH_SUPPORT
309 Enable 64-bit math support in the shell. This will make the shell
310 slightly larger, but will allow computation with very large numbers.
311 This is not in POSIX, so do not rely on this in portable code.
313 config FEATURE_SH_EXTRA_QUIET
314 bool "Hide message on interactive shell startup"
316 depends on HUSH || ASH
318 Remove the busybox introduction when starting a shell.
320 config FEATURE_SH_STANDALONE
321 bool "Standalone shell"
323 depends on (HUSH || ASH) && FEATURE_PREFER_APPLETS
325 This option causes busybox shells to use busybox applets
326 in preference to executables in the PATH whenever possible. For
327 example, entering the command 'ifconfig' into the shell would cause
328 busybox to use the ifconfig busybox applet. Specifying the fully
329 qualified executable name, such as '/sbin/ifconfig' will still
330 execute the /sbin/ifconfig executable on the filesystem. This option
331 is generally used when creating a statically linked version of busybox
332 for use as a rescue shell, in the event that you screw up your system.
334 This is implemented by re-execing /proc/self/exe (typically)
335 with right parameters. Some selected applets ("NOFORK" applets)
336 can even be executed without creating new process.
337 Instead, busybox will call <applet>_main() internally.
339 However, this causes problems in chroot jails without mounted /proc
340 and with ps/top (command name can be shown as 'exe' for applets
343 # Note that this will *also* cause applets to take precedence
344 # over shell builtins of the same name. So turning this on will
345 # eliminate any performance gained by turning on the builtin "echo"
346 # and "test" commands in ash.
348 # Note that when using this option, the shell will attempt to directly
349 # run '/bin/busybox'. If you do not have the busybox binary sitting in
350 # that exact location with that exact name, this option will not work at
353 config FEATURE_SH_NOFORK
354 bool "Run 'nofork' applets directly"
356 depends on (HUSH || ASH) && FEATURE_PREFER_APPLETS
358 This option causes busybox shells [currently only ash]
359 to not execute typical fork/exec/wait sequence, but call <applet>_main
360 directly, if possible. (Sometimes it is not possible: for example,
361 this is not possible in pipes).
363 This will be done only for some applets (those which are marked
364 NOFORK in include/applets.h).
366 This may significantly speed up some shell scripts.
368 This feature is relatively new. Use with care.
374 One common problem reported on the mailing list is "can't access tty;
375 job control turned off" error message which typically appears when
376 one tries to use shell with stdin/stdout opened to /dev/console.
377 This device is special - it cannot be a controlling tty.
379 Proper solution is to use correct device instead of /dev/console.
381 cttyhack provides "quick and dirty" solution to this problem.
382 It analyzes stdin with various ioctls, trying to determine whether
383 it is a /dev/ttyN or /dev/ttySN (virtual terminal or serial line).
384 If it detects one, it closes stdin/out/err and reopens that device.
385 Then it executes given program. Opening the device will make
386 that device a controlling tty. This may require cttyhack
387 to be a session leader.
389 Example for /etc/inittab (for busybox init):
391 ::respawn:/bin/cttyhack /bin/sh
393 Giving controlling tty to shell running with PID 1:
397 Starting an interactive shell from boot shell script: