2 # For a description of the syntax of this configuration file,
3 # see scripts/kbuild/config-language.txt.
9 prompt "Choose which shell is aliased to 'sh' name"
10 default FEATURE_SH_IS_ASH
12 Choose which shell you want to be executed by 'sh' alias.
13 The ash shell is the most bash compatible and full featured one.
15 config FEATURE_SH_IS_ASH
20 config FEATURE_SH_IS_HUSH
24 config FEATURE_SH_IS_NONE
30 prompt "Choose which shell is aliased to 'bash' name"
31 default FEATURE_BASH_IS_NONE
33 Choose which shell you want to be executed by 'bash' alias.
34 The ash shell is the most bash compatible and full featured one.
36 Note that selecting this option does not switch on any bash
37 compatibility code. It merely makes it possible to install
38 /bin/bash (sym)link and run scripts which start with
41 Many systems use it in scripts which use bash-specific features,
42 even simple ones like $RANDOM. Without this option, busybox
43 can't be used for running them because it won't recongnize
44 "bash" as a supported applet name.
46 config FEATURE_BASH_IS_ASH
51 config FEATURE_BASH_IS_HUSH
55 config FEATURE_BASH_IS_NONE
65 Tha 'ash' shell adds about 60k in the default configuration and is
66 the most complete and most pedantically correct shell included with
67 busybox. This shell is actually a derivative of the Debian 'dash'
68 shell (by Herbert Xu), which was created by porting the 'ash' shell
69 (written by Kenneth Almquist) from NetBSD.
71 config ASH_BASH_COMPAT
72 bool "bash-compatible extensions"
76 Enable bash-compatible extensions.
78 config ASH_JOB_CONTROL
83 Enable job control in the ash shell.
90 Enable alias support in the ash shell.
93 bool "Builtin getopt to parse positional parameters"
97 Enable getopts builtin in the ash shell.
99 config ASH_BUILTIN_ECHO
100 bool "Builtin version of 'echo'"
104 Enable support for echo, builtin to ash.
106 config ASH_BUILTIN_PRINTF
107 bool "Builtin version of 'printf'"
111 Enable support for printf, builtin to ash.
113 config ASH_BUILTIN_TEST
114 bool "Builtin version of 'test'"
118 Enable support for test, builtin to ash.
121 bool "'command' command to override shell builtins"
125 Enable support for the ash 'command' builtin, which allows
126 you to run the specified command with the specified arguments,
127 even when there is an ash builtin command with the same name.
130 bool "Check for new mail on interactive shells"
134 Enable "check for new mail" in the ash shell.
136 config ASH_OPTIMIZE_FOR_SIZE
137 bool "Optimize for size instead of speed"
141 Compile ash for reduced size at the price of speed.
143 config ASH_RANDOM_SUPPORT
144 bool "Pseudorandom generator and $RANDOM variable"
148 Enable pseudorandom generator and dynamic variable "$RANDOM".
149 Each read of "$RANDOM" will generate a new pseudorandom value.
150 You can reset the generator by using a specified start value.
151 After "unset RANDOM" the generator will switch off and this
152 variable will no longer have special treatment.
154 config ASH_EXPAND_PRMT
155 bool "Expand prompt string"
159 "PS#" may contain volatile content, such as backquote commands.
160 This option recreates the prompt string from the environment
161 variable each time it is displayed.
167 hush is a small shell (22k). It handles the normal flow control
168 constructs such as if/then/elif/else/fi, for/in/do/done, while loops,
169 case/esac. Redirections, here documents, $((arithmetic))
170 and functions are supported.
172 It will compile and work on no-mmu systems.
174 It does not handle select, aliases, brace expansion,
175 tilde expansion, &>file and >&file redirection of stdout+stderr.
177 config HUSH_BASH_COMPAT
178 bool "bash-compatible extensions"
182 Enable bash-compatible extensions.
189 Enable help builtin in hush. Code size + ~1 kbyte.
191 config HUSH_INTERACTIVE
192 bool "Interactive mode"
196 Enable interactive mode (prompt and command editing).
197 Without this, hush simply reads and executes commands
198 from stdin just like a shell script from a file.
199 No prompt, no PS1/PS2 magic shell variables.
204 depends on HUSH_INTERACTIVE
206 Enable job control: Ctrl-Z backgrounds, Ctrl-C interrupts current
207 command (not entire shell), fg/bg builtins work. Without this option,
208 "cmd &" still works by simply spawning a process and immediately
209 prompting for next command (or executing next command in a script),
210 but no separate process group is formed.
213 bool "Process substitution"
217 Enable process substitution `command` and $(command) in hush.
220 bool "Support if/then/elif/else/fi"
224 Enable if/then/elif/else/fi in hush.
227 bool "Support for, while and until loops"
231 Enable for, while and until loops in hush.
234 bool "Support case ... esac statement"
238 Enable case ... esac statement in hush. +400 bytes.
240 config HUSH_FUNCTIONS
241 bool "Support funcname() { commands; } syntax"
245 Enable support for shell functions in hush. +800 bytes.
248 bool "Support local builtin"
250 depends on HUSH_FUNCTIONS
252 Enable support for local variables in functions.
255 bool "Support export '-n' option"
259 Enable support for export '-n' option in hush. It is a bash extension.
261 config HUSH_RANDOM_SUPPORT
262 bool "Pseudorandom generator and $RANDOM variable"
266 Enable pseudorandom generator and dynamic variable "$RANDOM".
267 Each read of "$RANDOM" will generate a new pseudorandom value.
270 bool "lash (deprecated: aliased to hush)"
274 lash is deprecated and will be removed, please migrate to hush.
277 bool "msh (deprecated: please use hush)"
281 msh is deprecated and will be removed, please migrate to hush.
282 If there is a feature msh has but hush does not, please let us know.
284 # The minix shell (adds just 30k) is quite complete and handles things
285 # like for/do/done, case/esac and all the things you expect a Bourne
286 # shell to do. It is not always pedantically correct about Bourne
287 # shell grammar (try running the shell testscript "tests/sh.testcases"
288 # on it and compare vs bash) but for most things it works quite well.
289 # It uses only vfork, so it can be used on uClinux systems.
292 config SH_MATH_SUPPORT
293 bool "POSIX math support"
295 depends on ASH || HUSH
297 Enable math support in the shell via $((...)) syntax.
299 config SH_MATH_SUPPORT_64
300 bool "Extend POSIX math support to 64 bit"
302 depends on SH_MATH_SUPPORT
304 Enable 64-bit math support in the shell. This will make the shell
305 slightly larger, but will allow computation with very large numbers.
306 This is not in POSIX, so do not rely on this in portable code.
308 config FEATURE_SH_EXTRA_QUIET
309 bool "Hide message on interactive shell startup"
311 depends on HUSH || ASH
313 Remove the busybox introduction when starting a shell.
315 config FEATURE_SH_STANDALONE
316 bool "Standalone shell"
318 depends on (HUSH || ASH) && FEATURE_PREFER_APPLETS
320 This option causes busybox shells to use busybox applets
321 in preference to executables in the PATH whenever possible. For
322 example, entering the command 'ifconfig' into the shell would cause
323 busybox to use the ifconfig busybox applet. Specifying the fully
324 qualified executable name, such as '/sbin/ifconfig' will still
325 execute the /sbin/ifconfig executable on the filesystem. This option
326 is generally used when creating a statically linked version of busybox
327 for use as a rescue shell, in the event that you screw up your system.
329 This is implemented by re-execing /proc/self/exe (typically)
330 with right parameters. Some selected applets ("NOFORK" applets)
331 can even be executed without creating new process.
332 Instead, busybox will call <applet>_main() internally.
334 However, this causes problems in chroot jails without mounted /proc
335 and with ps/top (command name can be shown as 'exe' for applets
338 # Note that this will *also* cause applets to take precedence
339 # over shell builtins of the same name. So turning this on will
340 # eliminate any performance gained by turning on the builtin "echo"
341 # and "test" commands in ash.
343 # Note that when using this option, the shell will attempt to directly
344 # run '/bin/busybox'. If you do not have the busybox binary sitting in
345 # that exact location with that exact name, this option will not work at
348 config FEATURE_SH_NOFORK
349 bool "Run 'nofork' applets directly"
351 depends on (HUSH || ASH) && FEATURE_PREFER_APPLETS
353 This option causes busybox shells [currently only ash]
354 to not execute typical fork/exec/wait sequence, but call <applet>_main
355 directly, if possible. (Sometimes it is not possible: for example,
356 this is not possible in pipes).
358 This will be done only for some applets (those which are marked
359 NOFORK in include/applets.h).
361 This may significantly speed up some shell scripts.
363 This feature is relatively new. Use with care.
369 One common problem reported on the mailing list is "can't access tty;
370 job control turned off" error message which typically appears when
371 one tries to use shell with stdin/stdout opened to /dev/console.
372 This device is special - it cannot be a controlling tty.
374 Proper solution is to use correct device instead of /dev/console.
376 cttyhack provides "quick and dirty" solution to this problem.
377 It analyzes stdin with various ioctls, trying to determine whether
378 it is a /dev/ttyN or /dev/ttySN (virtual terminal or serial line).
379 If it detects one, it closes stdin/out/err and reopens that device.
380 Then it executes given program. Opening the device will make
381 that device a controlling tty. This may require cttyhack
382 to be a session leader.
384 Example for /etc/inittab (for busybox init):
386 ::respawn:/bin/cttyhack /bin/sh
388 Giving controlling tty to shell running with PID 1:
392 Starting an interactive shell from boot shell script: