2 # For a description of the syntax of this configuration file,
3 # see scripts/kbuild/config-language.txt.
9 prompt "Choose your default shell"
10 default FEATURE_SH_IS_NONE
12 Choose a shell. The ash shell is the most bash compatible
13 and full featured one.
15 config FEATURE_SH_IS_ASH
19 config FEATURE_SH_IS_HUSH
23 config FEATURE_SH_IS_LASH
27 config FEATURE_SH_IS_MSH
31 config FEATURE_SH_IS_NONE
41 Tha 'ash' shell adds about 60k in the default configuration and is
42 the most complete and most pedantically correct shell included with
43 busybox. This shell is actually a derivative of the Debian 'dash'
44 shell (by Herbert Xu), which was created by porting the 'ash' shell
45 (written by Kenneth Almquist) from NetBSD.
47 comment "Ash Shell Options"
50 config ASH_JOB_CONTROL
55 Enable job control in the ash shell.
57 config ASH_READ_NCHARS
58 bool "'read -n N' and 'read -s' support"
62 'read -n N' will return a value after N characters have been read.
63 'read -s' will read without echoing the user's input.
65 config ASH_READ_TIMEOUT
66 bool "'read -t S' support."
70 'read -t S' will return a value after S seconds have passed.
71 This implementation will allow fractional seconds, expressed
72 as a decimal fraction, e.g. 'read -t 2.5 foo'.
79 Enable alias support in the ash shell.
81 config ASH_MATH_SUPPORT
82 bool "Posix math support"
86 Enable math support in the ash shell.
88 config ASH_MATH_SUPPORT_64
89 bool "Extend Posix math support to 64 bit"
91 depends on ASH_MATH_SUPPORT
93 Enable 64-bit math support in the ash shell. This will make
94 the shell slightly larger, but will allow computation with very
98 bool "Builtin getopt to parse positional parameters"
102 Enable getopts builtin in the ash shell.
104 config ASH_BUILTIN_ECHO
105 bool "Builtin version of 'echo'"
110 Enable support for echo, builtin to ash.
112 config ASH_BUILTIN_TEST
113 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 variable $RANDOM"
148 Enable pseudorandom generator and dynamic variable "$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" then 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 be contain volatile content, such as backquote commands.
160 This option recreates the prompt string from the environment
161 variable each time it is displayed.
170 hush is a very small shell (just 18k) and it has fairly complete
171 Bourne shell grammar. It even handles all the normal flow control
172 options such as if/then/elif/else/fi, for/in/do/done, while loops,
175 It does not handle case/esac, select, function, here documents ( <<
176 word ), arithmetic expansion, aliases, brace expansion, tilde
177 expansion, &> and >& redirection of stdout+stderr, etc.
179 config HUSH_INTERACTIVE
180 bool "Interactive mode"
184 Enable interactive mode (prompt and command editing).
185 Without this, hush simply reads and executes commands
186 from stdin just like a shell script from the file.
187 No prompt, no PS1/PS2 magic shell variables.
192 depends on HUSH_INTERACTIVE
194 Enable job control: Ctrl-Z backgrounds, Ctrl-C interrupts current
195 command (not entire shell), fg/bg builtins work. Without this option,
196 "cmd &" still works by simply spawning a process and immediately
197 prompting for next command (or executing next command in a script),
198 but no separate process group is formed.
208 lash is the very smallest shell (adds just 10k) and it is quite
209 usable as a command prompt, but it is not suitable for any but the
210 most trivial scripting (such as an initrd that calls insmod a few
211 times) since it does not understand any Bourne shell grammar. It
212 does handle pipes, redirects, and job control though. Adding in
213 command editing makes it a very nice lightweight command prompt.
223 The minix shell (adds just 30k) is quite complete and handles things
224 like for/do/done, case/esac and all the things you expect a Bourne
225 shell to do. It is not always pedantically correct about Bourne
226 shell grammar (try running the shell testscript "tests/sh.testcases"
227 on it and compare vs bash) but for most things it works quite well.
228 It also uses only vfork, so it can be used on uClinux systems.
230 comment "Bourne Shell Options"
231 depends on MSH || LASH || HUSH || ASH
233 config FEATURE_SH_EXTRA_QUIET
234 bool "Hide message on interactive shell startup"
236 depends on MSH || LASH || HUSH || ASH
238 Remove the busybox introduction when starting a shell.
240 config FEATURE_SH_STANDALONE
241 bool "Standalone shell"
243 depends on (MSH || LASH || HUSH || ASH) && FEATURE_PREFER_APPLETS
245 This option causes busybox shells to use busybox applets
246 in preference to executables in the PATH whenever possible. For
247 example, entering the command 'ifconfig' into the shell would cause
248 busybox to use the ifconfig busybox applet. Specifying the fully
249 qualified executable name, such as '/sbin/ifconfig' will still
250 execute the /sbin/ifconfig executable on the filesystem. This option
251 is generally used when creating a statically linked version of busybox
252 for use as a rescue shell, in the event that you screw up your system.
254 This is implemented by re-execing /proc/self/exe (typically)
255 with right parameters. Some selected applets ("NOFORK" applets)
256 can even be executed without creating new process.
257 Instead, busybox will call <applet>_main() internally.
259 However, this causes problems in chroot jails without mounted /proc
260 and with ps/top (command name can be shown as 'exe' for applets
263 # Note that this will *also* cause applets to take precedence
264 # over shell builtins of the same name. So turning this on will
265 # eliminate any performance gained by turning on the builtin "echo"
266 # and "test" commands in ash.
268 # Note that when using this option, the shell will attempt to directly
269 # run '/bin/busybox'. If you do not have the busybox binary sitting in
270 # that exact location with that exact name, this option will not work at
277 One common problem reported on the mailing list is "can't access tty;
278 job control turned off" error message which typically appears when
279 one tries to use shell with stdin/stdout opened to /dev/console.
280 This device is special - it cannot be a controlling tty.
282 Proper solution is to use correct device instead of /dev/console.
284 cttyhack provides "quick and dirty" solution to this problem.
285 It analyzes stdin with various ioctls, trying to determine whether
286 it is a /dev/ttyN or /dev/ttySN (virtual terminal or serial line).
287 If it detects one, it closes stdin/out/err and reopens that device.
288 Then it executes given program. Usage example for /etc/inittab
291 ::respawn:/bin/cttyhack /bin/sh