# # 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 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. config ASH_BASH_COMPAT bool "bash-compatible extensions" default y depends on ASH help Enable bash-compatible extensions. 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_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 depends on ASH help Enable support for echo, builtin to ash. config ASH_BUILTIN_PRINTF bool "Builtin version of 'printf'" default y depends on ASH help Enable support for printf, builtin to ash. config ASH_BUILTIN_TEST bool "Builtin version of 'test'" default y 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 $RANDOM variable" default n depends on ASH help Enable pseudorandom generator and dynamic variable "$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" the 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 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 help hush is a small shell (22k). It handles the normal flow control constructs such as if/then/elif/else/fi, for/in/do/done, while loops, case/esac. Redirections, here documents, $((arithmetic)) and functions are supported. It will compile and work on no-mmu systems. It does not handle select, aliases, brace expansion, tilde expansion, &>file and >&file redirection of stdout+stderr. config HUSH_BASH_COMPAT bool "bash-compatible extensions" default y depends on HUSH help Enable bash-compatible extensions. 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 a 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 HUSH_CASE bool "Support case ... esac statement" default n depends on HUSH help Enable case ... esac statement in hush. +400 bytes. config HUSH_FUNCTIONS bool "Support funcname() { commands; } syntax" default n depends on HUSH help Enable support for shell functions in hush. +800 bytes. config HUSH_LOCAL bool "Support local builtin" default n depends on HUSH_FUNCTIONS help Enable support for local variables in functions. config HUSH_EXPORT_N bool "Support export '-n' option" default n depends on HUSH help Enable support for export '-n' option in hush. It is a bash extension. config HUSH_RANDOM_SUPPORT bool "Pseudorandom generator and $RANDOM variable" default n depends on HUSH help Enable pseudorandom generator and dynamic variable "$RANDOM". Each read of "$RANDOM" will generate a new pseudorandom value. config LASH bool "lash (deprecated: aliased to hush)" default n select HUSH help lash is deprecated and will be removed, please migrate to hush. config MSH bool "msh (deprecated: please use hush)" default n select HUSH help msh is deprecated and will be removed, please migrate to hush. If there is a feature msh has but hush does not, please let us know. # 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 uses only vfork, so it can be used on uClinux systems. config SH_MATH_SUPPORT bool "POSIX math support" default y depends on ASH || HUSH help Enable math support in the shell via $((...)) syntax. config SH_MATH_SUPPORT_64 bool "Extend POSIX math support to 64 bit" default n depends on SH_MATH_SUPPORT help Enable 64-bit math support in the shell. This will make the shell slightly larger, but will allow computation with very large numbers. This is not in POSIX, so do not rely on this in portable code. 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 <applet>_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 FEATURE_SH_NOFORK bool "Run 'nofork' applets directly" default n depends on (MSH || LASH || HUSH || ASH) && FEATURE_PREFER_APPLETS help This option causes busybox shells [currently only ash] to not execute typical fork/exec/wait sequence, but call <applet>_main directly, if possible. (Sometimes it is not possible: for example, this is not possible in pipes). This will be done only for some applets (those which are marked NOFORK in include/applets.h). This may significantly speed up some shell scripts. This feature is relatively new. Use with care. 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