Grub

let value_to_eol = store /[^= \t\n][^\n]*[^= \t\n]|[^= \t\n]/

let eol = Util.eol

let del_to_eol = del /[^ \t\n]*/ ""

let spc = Util.del_ws_spc

let opt_ws = Util.del_opt_ws ""

let dels (s:string) = Util.del_str s

let eq = dels "="

let switch (n:regexp) = dels "--" . key n

let switch_arg (n:regexp) = switch n . eq . store Rx.no_spaces

let value_sep (dflt:string) = del /[ \t]*[ \t=][ \t]*/ dflt

let comment_re = /([^ \t\n].*[^ \t\n]|[^ \t\n])/ - /# ## (Start|End) Default Options ##/

let comment = [ Util.indent . label "#comment" . del /#[ \t]*/ "# " . store comment_re . eol ]

let empty = Util.empty

let command (kw:regexp) (indent:string) = Util.del_opt_ws indent . key kw

let kw_arg (kw:regexp) (indent:string) (dflt_sep:string) = [ command kw indent . value_sep dflt_sep . value_to_eol . eol ]

let kw_boot_arg (kw:regexp) = kw_arg kw "\t" " "

let kw_menu_arg (kw:regexp) = kw_arg kw "" " "

let password_arg = [ command "password" "" . (spc . [ switch "md5" ])? . (spc . [ switch "encrypted" ])? . spc . store (/[^ \t\n]+/ - /--[^ \t\n]+/) . (spc . [ label "file" . store /[^ \t\n]+/ ])? . eol ]

let kw_pres (kw:string) = [ opt_ws . key kw . del_to_eol . eol ]

let device = [ command "device" "" . Sep.space . store /\([A-Za-z0-9_.-]+\)/ . spc . [ label "file" . value_to_eol ] . Util.eol ]

This is a shell-only directive in upstream grub; the grub versions in at least Fedora/RHEL use this to find devices for UEFI boot

let color =

let serial = [ command "serial" "" . [ spc . switch_arg /unit|port|speed|word|parity|stop|device/ ]* . eol ]

let terminal = [ command "terminal" "" . ([ spc . switch /dumb|no-echo|no-edit|silent/ ] |[ spc . switch_arg /timeout|lines/ ])* . [ spc . key /console|serial|hercules/ ]* . eol ]

let setkey = [ command "setkey" "" . ( spc . [ label "to" . store Rx.no_spaces ] . spc . [ label "from" . store Rx.no_spaces ] )? . eol ]

let menu_setting = kw_menu_arg "default" | kw_menu_arg "fallback" | kw_pres "hiddenmenu" | kw_menu_arg "timeout" | kw_menu_arg "splashimage" | kw_menu_arg "gfxmenu" | kw_menu_arg "foreground" | kw_menu_arg "background" | kw_menu_arg "verbose" | serial | terminal | password_arg | color | device | setkey

let title = del /title[ \t=]+/ "title " . value_to_eol . eol

let multiboot_arg = [ label "@path" . store (Rx.word . "/" . Rx.no_spaces) ]

Permits a second form for Solaris multiboot kernels that take a path (with a slash) as their first arg, e.g.  /boot/multiboot kernel/unix another=arg

let kernel_args = let arg = /[A-Za-z0-9_.$-]+/ - /type|no-mem-option/ in store /(\([a-z0-9,]+\))?\/[^ \t\n]*/ . (spc . multiboot_arg)? . (spc . [ key arg . (eq. store /([^ \t\n])*/)?])* . eol

Parse the file name and args on a kernel or module line.

let module_line = [ command /module\$?/ "\t" . spc . kernel_args ]

Solaris extension adds module$ and kernel$ for variable interpolation

let map_line = [ command "map" "\t" . spc . [ label "from" . store /[()A-za-z0-9]+/ ] . spc . [ label "to" . store /[()A-za-z0-9]+/ ] . eol ]

let kernel = [ command /kernel\$?/ "\t" . (spc . ([switch "type" . eq . store /[a-z]+/] |[switch "no-mem-option"]))* . spc . kernel_args ]

let chainloader = [ command "chainloader" "\t" . [ spc . switch "force" ]? . spc . store Rx.no_spaces . eol ]

let savedefault = [ command "savedefault" "\t" . (spc . store Rx.integer)? . eol ]

let configfile = [ command "configfile" "\t" . spc . store Rx.no_spaces . eol ]

let boot_setting = let boot_arg_re = "root" | "initrd" | "rootnoverify" | "uuid" | "findroot" | "bootfs" (* Solaris extensions *) in kw_boot_arg boot_arg_re | kernel | chainloader | kw_pres "quiet" (* Seems to be a Ubuntu extension *) | savedefault | configfile | module_line | map_line | kw_pres "lock" | kw_pres "makeactive" | password_arg

boot entries

let boot = let line = ((boot_setting|comment)* . boot_setting)? in [ label "title" . title . line ]

let debian_header = "## ## Start Default Options ##\n"

Header for a debian-specific section

let debian_footer = "## ## End Default Options ##\n"

Footer for a debian-specific section

let debian_comment_re = /([^ \t\n].*[^ \t\n]|[^ \t\n])/ - "## End Default Options ##"

let debian_comment = [ Util.indent . label "#comment" . del /##[ \t]*/ "## " . store debian_comment_re . eol ]

A comment entry inside a debian-specific section

let debian_setting_re = "kopt" | "groot" | "alternative" | "lockalternative" | "defoptions" | "lockold" | "xenhopt" | "xenkopt" | "altoptions" | "howmany" | "memtest86" | "updatedefaultentry" | "savedefault" | "indomU"

let debian_entry = [ Util.del_str "#" . Util.indent . key debian_setting_re . del /[ \t]*=/ "=" . value_to_eol? . eol ]

let debian = [ label "debian" . del debian_header debian_header . (debian_comment|empty|debian_entry)* . del debian_footer debian_footer ]

A debian-specific section, made of debian_entry lines

let lns = (comment | empty | menu_setting | debian)* . (boot . (comment | empty | boot)*)?