# # For a description of the syntax of this configuration file, # see scripts/kbuild/config-language.txt. # comment "-------------------------------------------------" comment "Shells" comment "-------------------------------------------------" config KEMBTK_BUSYB_ASH bool "ash" default y depends on !KEMBTK_BUSYB_NOMMU 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 KEMBTK_BUSYB_ASH_BASH_COMPAT bool "bash-compatible extensions" default y depends on KEMBTK_BUSYB_ASH help Enable bash-compatible extensions. config KEMBTK_BUSYB_ASH_IDLE_TIMEOUT bool "Idle timeout variable" depends on KEMBTK_BUSYB_ASH help Enables bash-like auto-logout after $TMOUT seconds of idle time. config KEMBTK_BUSYB_ASH_JOB_CONTROL bool "Job control" default y depends on KEMBTK_BUSYB_ASH help Enable job control in the ash shell. config KEMBTK_BUSYB_ASH_ALIAS bool "Alias support" default y depends on KEMBTK_BUSYB_ASH help Enable alias support in the ash shell. config KEMBTK_BUSYB_ASH_GETOPTS bool "Builtin getopt to parse positional parameters" default y depends on KEMBTK_BUSYB_ASH help Enable support for getopts builtin in ash. config KEMBTK_BUSYB_ASH_BUILTIN_ECHO bool "Builtin version of 'echo'" default y depends on KEMBTK_BUSYB_ASH help Enable support for echo builtin in ash. config KEMBTK_BUSYB_ASH_BUILTIN_PRINTF bool "Builtin version of 'printf'" default y depends on KEMBTK_BUSYB_ASH help Enable support for printf builtin in ash. config KEMBTK_BUSYB_ASH_BUILTIN_TEST bool "Builtin version of 'test'" default y depends on KEMBTK_BUSYB_ASH help Enable support for test builtin in ash. config KEMBTK_BUSYB_ASH_CMDCMD bool "'command' command to override shell builtins" default y depends on KEMBTK_BUSYB_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 KEMBTK_BUSYB_ASH_MAIL bool "Check for new mail on interactive shells" depends on KEMBTK_BUSYB_ASH help Enable "check for new mail" function in the ash shell. config KEMBTK_BUSYB_ASH_OPTIMIZE_FOR_SIZE bool "Optimize for size instead of speed" default y depends on KEMBTK_BUSYB_ASH help Compile ash for reduced size at the price of speed. config KEMBTK_BUSYB_ASH_RANDOM_SUPPORT bool "Pseudorandom generator and $RANDOM variable" default y depends on KEMBTK_BUSYB_ASH help Enable pseudorandom generator and dynamic variable "$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 KEMBTK_BUSYB_ASH_EXPAND_PRMT bool "Expand prompt string" default y depends on KEMBTK_BUSYB_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 KEMBTK_BUSYB_CTTYHACK bool "cttyhack" default y help One common problem reported on the mailing list is the "can't access tty; job control turned off" error message, which typically appears when one tries to use a shell with stdin/stdout on /dev/console. This device is special - it cannot be a controlling tty. The proper solution is to use the correct device instead of /dev/console. cttyhack provides a "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). On Linux it also checks sysfs for a pointer to the active console. If cttyhack is able to find the real console device, it closes stdin/out/err and reopens that device. Then it executes the given program. Opening the device will make that device a controlling tty. This may require cttyhack to be a session leader. Example for /etc/inittab (for busybox init): ::respawn:/bin/cttyhack /bin/sh Starting an interactive shell from boot shell script: setsid cttyhack sh Giving controlling tty to shell running with PID 1: # exec cttyhack sh Without cttyhack, you need to know exact tty name, and do something like this: # exec setsid sh -c 'exec sh /dev/tty1 2>&1' Starting getty on a controlling tty from a shell script: # getty 115200 $(cttyhack) config KEMBTK_BUSYB_HUSH bool "hush" default y help hush is a small shell (25k). 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, tilde expansion, &>file and >&file redirection of stdout+stderr. config KEMBTK_BUSYB_HUSH_BASH_COMPAT bool "bash-compatible extensions" default y depends on KEMBTK_BUSYB_HUSH help Enable bash-compatible extensions. config KEMBTK_BUSYB_HUSH_BRACE_EXPANSION bool "Brace expansion" default y depends on KEMBTK_BUSYB_HUSH_BASH_COMPAT help Enable {abc,def} extension. config KEMBTK_BUSYB_HUSH_HELP bool "help builtin" default y depends on KEMBTK_BUSYB_HUSH help Enable help builtin in hush. Code size + ~1 kbyte. config KEMBTK_BUSYB_HUSH_INTERACTIVE bool "Interactive mode" default y depends on KEMBTK_BUSYB_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 KEMBTK_BUSYB_PS1/PS2 magic shell variables. config KEMBTK_BUSYB_HUSH_SAVEHISTORY bool "Save command history to .hush_history" default y depends on KEMBTK_BUSYB_HUSH_INTERACTIVE && KEMBTK_BUSYB_FEATURE_EDITING_SAVEHISTORY help Enable history saving in hush. config KEMBTK_BUSYB_HUSH_JOB bool "Job control" default y depends on KEMBTK_BUSYB_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 KEMBTK_BUSYB_HUSH_TICK bool "Process substitution" default y depends on KEMBTK_BUSYB_HUSH help Enable process substitution `command` and $(command) in hush. config KEMBTK_BUSYB_HUSH_IF bool "Support if/then/elif/else/fi" default y depends on KEMBTK_BUSYB_HUSH help Enable if/then/elif/else/fi in hush. config KEMBTK_BUSYB_HUSH_LOOPS bool "Support for, while and until loops" default y depends on KEMBTK_BUSYB_HUSH help Enable for, while and until loops in hush. config KEMBTK_BUSYB_HUSH_CASE bool "Support case ... esac statement" default y depends on KEMBTK_BUSYB_HUSH help Enable case ... esac statement in hush. +400 bytes. config KEMBTK_BUSYB_HUSH_FUNCTIONS bool "Support funcname() { commands; } syntax" default y depends on KEMBTK_BUSYB_HUSH help Enable support for shell functions in hush. +800 bytes. config KEMBTK_BUSYB_HUSH_LOCAL bool "Support local builtin" default y depends on KEMBTK_BUSYB_HUSH_FUNCTIONS help Enable support for local variables in functions. config KEMBTK_BUSYB_HUSH_RANDOM_SUPPORT bool "Pseudorandom generator and $RANDOM variable" default y depends on KEMBTK_BUSYB_HUSH help Enable pseudorandom generator and dynamic variable "$RANDOM". Each read of "$RANDOM" will generate a new pseudorandom value. config KEMBTK_BUSYB_HUSH_EXPORT_N bool "Support 'export -n' option" default y depends on KEMBTK_BUSYB_HUSH help export -n unexports variables. It is a bash extension. config KEMBTK_BUSYB_HUSH_MODE_X bool "Support 'hush -x' option and 'set -x' command" default y depends on KEMBTK_BUSYB_HUSH help This instructs hush to print commands before execution. Adds ~300 bytes. config KEMBTK_BUSYB_MSH bool "msh (deprecated: aliased to hush)" select KEMBTK_BUSYB_HUSH help msh is deprecated and will be removed, please migrate to hush. choice prompt "Choose which shell is aliased to 'sh' name" help Choose which shell you want to be executed by 'sh' alias. The ash shell is the most bash compatible and full featured one. # note: cannot use "select KEMBTK_BUSYB_ASH" here, it breaks "make allnoconfig" config KEMBTK_BUSYB_FEATURE_SH_IS_ASH depends on KEMBTK_BUSYB_ASH bool "ash" depends on !KEMBTK_BUSYB_NOMMU config KEMBTK_BUSYB_FEATURE_SH_IS_HUSH depends on KEMBTK_BUSYB_HUSH bool "hush" config KEMBTK_BUSYB_FEATURE_SH_IS_NONE bool "none" endchoice choice prompt "Choose which shell is aliased to 'bash' name" help Choose which shell you want to be executed by 'bash' alias. The ash shell is the most bash compatible and full featured one. Note that selecting this option does not switch on any bash compatibility code. It merely makes it possible to install /bin/bash (sym)link and run scripts which start with #!/bin/bash line. Many systems use it in scripts which use bash-specific features, even simple ones like $RANDOM. Without this option, busybox can't be used for running them because it won't recongnize "bash" as a supported applet name. config KEMBTK_BUSYB_FEATURE_BASH_IS_ASH depends on KEMBTK_BUSYB_ASH bool "ash" depends on !KEMBTK_BUSYB_NOMMU config KEMBTK_BUSYB_FEATURE_BASH_IS_HUSH depends on KEMBTK_BUSYB_HUSH bool "hush" config KEMBTK_BUSYB_FEATURE_BASH_IS_NONE bool "none" endchoice config KEMBTK_BUSYB_SH_MATH_SUPPORT bool "POSIX math support" default y depends on KEMBTK_BUSYB_ASH || KEMBTK_BUSYB_HUSH help Enable math support in the shell via $((...)) syntax. config KEMBTK_BUSYB_SH_MATH_SUPPORT_64 bool "Extend POSIX math support to 64 bit" default y depends on KEMBTK_BUSYB_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 KEMBTK_BUSYB_FEATURE_SH_EXTRA_QUIET bool "Hide message on interactive shell startup" default y depends on KEMBTK_BUSYB_HUSH || KEMBTK_BUSYB_ASH help Remove the busybox introduction when starting a shell. config KEMBTK_BUSYB_FEATURE_SH_STANDALONE bool "Standalone shell" depends on (KEMBTK_BUSYB_HUSH || KEMBTK_BUSYB_ASH) && KEMBTK_BUSYB_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 KEMBTK_BUSYB_FEATURE_SH_NOFORK bool "Run 'nofork' applets directly" depends on (KEMBTK_BUSYB_HUSH || KEMBTK_BUSYB_ASH) && KEMBTK_BUSYB_FEATURE_PREFER_APPLETS help This option causes busybox shells to not execute typical fork/exec/wait sequence, but call _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. Report bugs to project mailing list. config KEMBTK_BUSYB_FEATURE_SH_HISTFILESIZE bool "Use $HISTFILESIZE" default y depends on KEMBTK_BUSYB_HUSH || KEMBTK_BUSYB_ASH help This option makes busybox shells to use $HISTFILESIZE variable to set shell history size. Note that its max value is capped by "History size" setting in library tuning section.