# # For a description of the syntax of this configuration file, # see scripts/kbuild/config-language.txt. # menu "Shells" choice prompt "Choose your default shell" default FEATURE_SH_IS_NONE help Choose a shell. The ash shell is the most bash compatible and full featured one. config FEATURE_SH_IS_ASH select ASH bool "ash" config FEATURE_SH_IS_HUSH select HUSH bool "hush" config FEATURE_SH_IS_LASH select LASH bool "lash" config FEATURE_SH_IS_MSH select MSH bool "msh" config FEATURE_SH_IS_NONE bool "none" endchoice config ASH bool "ash" default n select TEST help Tha 'ash' shell adds about 60k in the default configuration and is the most complete and most pedantically correct shell included with busybox. This shell is actually a derivative of the Debian 'dash' shell (by Herbert Xu), which was created by porting the 'ash' shell (written by Kenneth Almquist) from NetBSD. comment "Ash Shell Options" depends on ASH config ASH_JOB_CONTROL bool "Job control" default y depends on ASH help Enable job control in the ash shell. config ASH_READ_NCHARS bool "'read -n N' and 'read -s' support" default n depends on ASH help 'read -n N' will return a value after N characters have been read. 'read -s' will read without echoing the user's input. config ASH_READ_TIMEOUT bool "'read -t S' support." default n depends on ASH help 'read -t S' will return a value after S seconds have passed. This implementation will allow fractional seconds, expressed as a decimal fraction, e.g. 'read -t 2.5 foo'. config ASH_ALIAS bool "alias support" default y depends on ASH help Enable alias support in the ash shell. config ASH_MATH_SUPPORT bool "Posix math support" default y depends on ASH help Enable math support in the ash shell. config ASH_MATH_SUPPORT_64 bool "Extend Posix math support to 64 bit" default n depends on ASH_MATH_SUPPORT help Enable 64-bit math support in the ash shell. This will make the shell slightly larger, but will allow computation with very large numbers. config ASH_GETOPTS bool "Builtin getopt to parse positional parameters" default n depends on ASH help Enable getopts builtin in the ash shell. config ASH_BUILTIN_ECHO bool "Builtin version of 'echo'" default y select ECHO depends on ASH help Enable support for echo, builtin to ash. config ASH_BUILTIN_TEST bool "Builtin version of 'test'" default y select TEST depends on ASH help Enable support for test, builtin to ash. config ASH_CMDCMD bool "'command' command to override shell builtins" default n depends on ASH help Enable support for the ash 'command' builtin, which allows you to run the specified command with the specified arguments, even when there is an ash builtin command with the same name. config ASH_MAIL bool "Check for new mail on interactive shells" default y depends on ASH help Enable "check for new mail" in the ash shell. config ASH_OPTIMIZE_FOR_SIZE bool "Optimize for size instead of speed" default y depends on ASH help Compile ash for reduced size at the price of speed. config ASH_RANDOM_SUPPORT bool "Pseudorandom generator and variable $RANDOM" default n depends on ASH help Enable pseudorandom generator and dynamic variable "$RANDOM". Each read of "$RANDOM" will generate a new pseudorandom value. You can reset the generator by using a specified start value. After "unset RANDOM" then generator will switch off and this variable will no longer have special treatment. config ASH_EXPAND_PRMT bool "Expand prompt string" default n depends on ASH help "PS#" may be contain volatile content, such as backquote commands. This option recreates the prompt string from the environment variable each time it is displayed. config HUSH bool "hush" default n select TRUE select FALSE select TEST help hush is a very small shell (just 18k) and it has fairly complete Bourne shell grammar. It even handles all the normal flow control options such as if/then/elif/else/fi, for/in/do/done, while loops, etc. It does not handle case/esac, select, function, here documents ( << word ), arithmetic expansion, aliases, brace expansion, tilde expansion, &> and >& redirection of stdout+stderr, etc. config HUSH_HELP bool "help builtin" default n depends on HUSH help Enable help builtin in hush. Code size + ~1 kbyte. config HUSH_INTERACTIVE bool "Interactive mode" default y depends on HUSH help Enable interactive mode (prompt and command editing). Without this, hush simply reads and executes commands from stdin just like a shell script from the file. No prompt, no PS1/PS2 magic shell variables. config HUSH_JOB bool "Job control" default n depends on HUSH_INTERACTIVE help Enable job control: Ctrl-Z backgrounds, Ctrl-C interrupts current command (not entire shell), fg/bg builtins work. Without this option, "cmd &" still works by simply spawning a process and immediately prompting for next command (or executing next command in a script), but no separate process group is formed. config HUSH_TICK bool "Process substitution" default n depends on HUSH help Enable process substitution `command` and $(command) in hush. config HUSH_IF bool "Support if/then/elif/else/fi" default n depends on HUSH help Enable if/then/elif/else/fi in hush. config HUSH_LOOPS bool "Support for, while and until loops" default n depends on HUSH help Enable for, while and until loops in hush. config LASH bool "lash" default n select TRUE select FALSE select TEST help lash is the very smallest shell (adds just 10k) and it is quite usable as a command prompt, but it is not suitable for any but the most trivial scripting (such as an initrd that calls insmod a few times) since it does not understand any Bourne shell grammar. It does handle pipes, redirects, and job control though. Adding in command editing makes it a very nice lightweight command prompt. config MSH bool "msh" default n select TRUE select FALSE select TEST help The minix shell (adds just 30k) is quite complete and handles things like for/do/done, case/esac and all the things you expect a Bourne shell to do. It is not always pedantically correct about Bourne shell grammar (try running the shell testscript "tests/sh.testcases" on it and compare vs bash) but for most things it works quite well. It also uses only vfork, so it can be used on uClinux systems. comment "Bourne Shell Options" depends on MSH || LASH || HUSH || ASH config FEATURE_SH_EXTRA_QUIET bool "Hide message on interactive shell startup" default n depends on MSH || LASH || HUSH || ASH help Remove the busybox introduction when starting a shell. config FEATURE_SH_STANDALONE bool "Standalone shell" default n depends on (MSH || LASH || HUSH || ASH) && FEATURE_PREFER_APPLETS help This option causes busybox shells to use busybox applets in preference to executables in the PATH whenever possible. For example, entering the command 'ifconfig' into the shell would cause busybox to use the ifconfig busybox applet. Specifying the fully qualified executable name, such as '/sbin/ifconfig' will still execute the /sbin/ifconfig executable on the filesystem. This option is generally used when creating a statically linked version of busybox for use as a rescue shell, in the event that you screw up your system. This is implemented by re-execing /proc/self/exe (typically) with right parameters. Some selected applets ("NOFORK" applets) can even be executed without creating new process. Instead, busybox will call _main() internally. However, this causes problems in chroot jails without mounted /proc and with ps/top (command name can be shown as 'exe' for applets started this way). # untrue? # Note that this will *also* cause applets to take precedence # over shell builtins of the same name. So turning this on will # eliminate any performance gained by turning on the builtin "echo" # and "test" commands in ash. # untrue? # Note that when using this option, the shell will attempt to directly # run '/bin/busybox'. If you do not have the busybox binary sitting in # that exact location with that exact name, this option will not work at # all. config CTTYHACK bool "cttyhack" default n help One common problem reported on the mailing list is "can't access tty; job control turned off" error message which typically appears when one tries to use shell with stdin/stdout opened to /dev/console. This device is special - it cannot be a controlling tty. Proper solution is to use correct device instead of /dev/console. cttyhack provides "quick and dirty" solution to this problem. It analyzes stdin with various ioctls, trying to determine whether it is a /dev/ttyN or /dev/ttySN (virtual terminal or serial line). If it detects one, it closes stdin/out/err and reopens that device. Then it executes given program. Usage example for /etc/inittab (for busybox init): ::respawn:/bin/cttyhack /bin/sh endmenu