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.
115 prompt "Choose which shell is aliased to 'sh' name"
116 default FEATURE_SH_IS_ASH
118 Choose which shell you want to be executed by 'sh' alias.
119 The ash shell is the most bash compatible and full featured one.
121 # note: cannot use "select ASH" here, it breaks "make allnoconfig"
122 config FEATURE_SH_IS_ASH
127 config FEATURE_SH_IS_HUSH
131 config FEATURE_SH_IS_NONE
137 prompt "Choose which shell is aliased to 'bash' name"
138 default FEATURE_BASH_IS_NONE
140 Choose which shell you want to be executed by 'bash' alias.
141 The ash shell is the most bash compatible and full featured one.
143 Note that selecting this option does not switch on any bash
144 compatibility code. It merely makes it possible to install
145 /bin/bash (sym)link and run scripts which start with
148 Many systems use it in scripts which use bash-specific features,
149 even simple ones like $RANDOM. Without this option, busybox
150 can't be used for running them because it won't recongnize
151 "bash" as a supported applet name.
153 config FEATURE_BASH_IS_ASH
158 config FEATURE_BASH_IS_HUSH
162 config FEATURE_BASH_IS_NONE
169 bool "lash (deprecated: aliased to hush)"
173 lash is deprecated and will be removed, please migrate to hush.
176 bool "msh (deprecated: please use hush)"
180 msh is deprecated and will be removed, please migrate to hush.
181 If there is a feature msh has but hush does not, please let us know.
183 # The minix shell (adds just 30k) is quite complete and handles things
184 # like for/do/done, case/esac and all the things you expect a Bourne
185 # shell to do. It is not always pedantically correct about Bourne
186 # shell grammar (try running the shell testscript "tests/sh.testcases"
187 # on it and compare vs bash) but for most things it works quite well.
188 # It uses only vfork, so it can be used on uClinux systems.
191 config SH_MATH_SUPPORT
192 bool "POSIX math support"
194 depends on ASH || HUSH
196 Enable math support in the shell via $((...)) syntax.
198 config SH_MATH_SUPPORT_64
199 bool "Extend POSIX math support to 64 bit"
201 depends on SH_MATH_SUPPORT
203 Enable 64-bit math support in the shell. This will make the shell
204 slightly larger, but will allow computation with very large numbers.
205 This is not in POSIX, so do not rely on this in portable code.
207 config FEATURE_SH_EXTRA_QUIET
208 bool "Hide message on interactive shell startup"
210 depends on HUSH || ASH
212 Remove the busybox introduction when starting a shell.
214 config FEATURE_SH_STANDALONE
215 bool "Standalone shell"
217 depends on (HUSH || ASH) && FEATURE_PREFER_APPLETS
219 This option causes busybox shells to use busybox applets
220 in preference to executables in the PATH whenever possible. For
221 example, entering the command 'ifconfig' into the shell would cause
222 busybox to use the ifconfig busybox applet. Specifying the fully
223 qualified executable name, such as '/sbin/ifconfig' will still
224 execute the /sbin/ifconfig executable on the filesystem. This option
225 is generally used when creating a statically linked version of busybox
226 for use as a rescue shell, in the event that you screw up your system.
228 This is implemented by re-execing /proc/self/exe (typically)
229 with right parameters. Some selected applets ("NOFORK" applets)
230 can even be executed without creating new process.
231 Instead, busybox will call <applet>_main() internally.
233 However, this causes problems in chroot jails without mounted /proc
234 and with ps/top (command name can be shown as 'exe' for applets
237 # Note that this will *also* cause applets to take precedence
238 # over shell builtins of the same name. So turning this on will
239 # eliminate any performance gained by turning on the builtin "echo"
240 # and "test" commands in ash.
242 # Note that when using this option, the shell will attempt to directly
243 # run '/bin/busybox'. If you do not have the busybox binary sitting in
244 # that exact location with that exact name, this option will not work at
247 config FEATURE_SH_NOFORK
248 bool "Run 'nofork' applets directly"
250 depends on (HUSH || ASH) && FEATURE_PREFER_APPLETS
252 This option causes busybox shells [currently only ash]
253 to not execute typical fork/exec/wait sequence, but call <applet>_main
254 directly, if possible. (Sometimes it is not possible: for example,
255 this is not possible in pipes).
257 This will be done only for some applets (those which are marked
258 NOFORK in include/applets.h).
260 This may significantly speed up some shell scripts.
262 This feature is relatively new. Use with care.
268 One common problem reported on the mailing list is "can't access tty;
269 job control turned off" error message which typically appears when
270 one tries to use shell with stdin/stdout opened to /dev/console.
271 This device is special - it cannot be a controlling tty.
273 Proper solution is to use correct device instead of /dev/console.
275 cttyhack provides "quick and dirty" solution to this problem.
276 It analyzes stdin with various ioctls, trying to determine whether
277 it is a /dev/ttyN or /dev/ttySN (virtual terminal or serial line).
278 If it detects one, it closes stdin/out/err and reopens that device.
279 Then it executes given program. Opening the device will make
280 that device a controlling tty. This may require cttyhack
281 to be a session leader.
283 Example for /etc/inittab (for busybox init):
285 ::respawn:/bin/cttyhack /bin/sh
287 Giving controlling tty to shell running with PID 1:
291 Starting an interactive shell from boot shell script: