source: drbl_ui/backup/test_busybox/busybox-1.7.2/shell/Config.in @ 129

#
# 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 <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 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