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flash.1

Manvendra Bhangui edited this page Nov 22, 2023 · 2 revisions

NAME

flash - Secure Host Interface - A menu shell with hotkeys and process group management

SYNOPSIS

flash [-hVl] [-b basedirectory] [-d delimiter] [-e escape] [-c comment] [menu file]

DESCRIPTION

flash is a secure menuing shell (quite different from what its name suggests). flash loads menu file, interprets and displays it. The menu is made up of a combination of token structures seperated by line breaks.

OPTIONS

-h
Print a help message and usage information.

-V
Print version information and compile-time defaults.

-b basedirectory
Set the directory that flash should expect to find its configuration files.

-d filename
Set the debug file to filename.

-c command
An ordinary shell would run command, flash just logs the attempt to the syslog.

menu file
Load menu from menu file.

FILE FORMAT

Note: I will be using `:' as the token delimiter, `\ as the escape character, and `#' as the comment character throughout this document. Directive matching is case insensitive.

Flash files are made up of a series of token structures and directives. There is a limit of one token structure or directive per line.

Lines beginning with `#' will be ignored by flash. Characters preceded by `\ will be treated literally by flash.

Directives

Directives tell flash how to interperet text.

Menu [menu options] name
Starts a menu named name, all following lines will be interpereted as menu token structures until the EndMenu is read. If a menu main is present in the file it is stared first, otherwise the first menu encountered is used.

RCBlock [rc options]
Interperet the following lines as rc token structures until EndRCBlock is read. These blocks allow configuration of flash or execution of programs at run time.

RCFile [rc options] filename
Read filename and interperet its lines as rc token structures until the end of the file.

Module [module name] [module options]

Include filename [filenames...]
Include further menu files.

MainMenuName name
Specify the name of the initial menu. Defaults to "Main".

NoBox
Default to displaying menus without border boxes.

Menu [menu options] name

A number of menu options may be used to control the appearance of the menu on the screen. Options are seperated by whitespaces.

NoBox
The menu should be displayed without a border box.

Left
The menu should be displayed on the left of the screen.

Right
The menu should be displayed on the right of the screen.

Top
The menu should be displayed at the top of the screen.

Bottom
The menu should be displayed at the bottom of the screen.

Offset y x
Offset the menu y lines and x columns from the location specified using the above options.

Password x
Set an access password for this menu. x is the access password encrypted using SHA. Passwords can be generated using the shacrypt program included with the distribution.

The menu is defined by token structures, which are enclosed within a Menu directive, with one structure per line. A token structure is made up of at least two fields separated by delimiters. The last field must end with a delimiter. The format of the token structure is:

Token:Name:Options:Args:Prompt:

Where Token is the type of item to display. Name is the name of the item as displayed on the menu. The Options sets flags which control the display of the item and in some cases the response to selection of the menu item. Args is an item dependent argument field. Prompt is a text string which is used in some of the tokens. Every token line must at least contain the Token and Name fields, the others are either optional or present in only some of the tokens. For compatibility with menus from flash the fields have the following precidence which determines in what order they are interpreted Token, Name, Args, Prompt and Options.

Menu Tokens

Title
Title inserts a non-selectable title line in the menu.

Title:Name:
or
Title:Name:Options:

Nop
Nop inserts a non-selectable line in the menu. If the item text is blank then a horizontal line will be displayed.

Nop:Name:
or
Nop:Name:Options:
or
Nop::

SubMenu
SubMenu creates a link to another menu named in the Args field.

SubMenu:Name:Args:
or
SubMenu:Name:Options:Args:

Exec
Exec executes the command specified in the Args field. The process is put into a seperate process group. Note that the command is started using execvp which will search the PATH if the command is not specified absolutely, this may not be what you want for a secure setup.

Exec:Name:Args:
or
Exec:Name:Options:Args:

Args
Args executes the command in the Args field with user inputted command-line arguments. The optional Prompt field contains the prompt for the dialog box. Use with care! If you use this improperly, you could open up a big security whole on your system.

Args:Name:Args:
or
Args:Name:Args:Prompt:
or
Args:Name:Options:Args:Prompt:

Exit
Exit exits the current menu, returning to the previous menu. If Exit is executed in the main menu flash will quit.

Exit:Name:
or
Exit:Name:Options:

Quit
Exits flash.

Quit:Name:
or
Quit:Name:Options:

Menu Token Options

There are a number Options defined for all of the menu tokens. These control the display of the item on the menu. These are

L
Display the item flush left on the menu

C
Display the item centred in the menu

R
Display the item flushed right in the menu

Kx
Define a hotkey x for this menu item.

In addition the following options are defined for the Exec and Args tokens

P
The output from the process should be paged using a default pager

N
flash should not pause for the user to press a key when the process exits unless it returns an error.

&
The process should be started in the background.

RCFile [rc options] filename

RCBlock [rc options]

A number of rc options may be used to select what scope the block has.

Login
The RCBlock or RCFile should only be processed if the shell is a login shell.

System
This option is available in RCFile only. It specifies that the file to be read will have system rc privilage. Commands can be restricted so that they can only appear in system rc files. All RCBlocks are system. System RCFiles are sought relative to the baseaddress while non-system RCFiles are sought in users' home directories.

EXAMPLE MENU

Here is an example menu (comment character is `#', delimiter is `:'):

#!./flash -b.
#
# test.menu	-	sample menu implementation for flash
#			to try it out type:
#			`./flash test.menu' or `./test.menu'
# Main menu
Menu NoBox NoColour Top Right Offset 1 -2 Main
	SubMenu:Electronic Mail:C:Mail:
	SubMenu:Network Facilities:C:Facilities:
	SubMenu:Local Chat:C:Talk:
	SubMenu:Who Else Is Online?:C:Else:
	SubMenu:Other System Information:C:SysInfo:
	SubMenu:Customise Your Account:C:Customise:
	SubMenu:Send Comments to Netsoc:C:Comments:
	SubMenu:Read Help Files:C:Help:
	SubMenu:Administration Menu:C:Admin:
	Title::
	Quit:Logout:C:
EndMenu

Menu Mail
	Title:Read, Send or Review your e-mail:
	Nop::
	Nop::
	Exec:Elm:N:elm:
	Nop:Powerful - built in encrypted mail support:
	Exec:Pine:N:pine:
	Nop:Very easy-to-use, excellent help facilities:
	Exit:Exit this menu:
EndMenu

Menu Facilities
	Title:Programs to do with Network Access:
	Nop::
	SubMenu:Network News:News:
	SubMenu:World Wide Web:Web:
	Nop::
	Exit:Exit This Menu:
EndMenu

Menu News
	Title:Read, Reply to and Barf at Network News:
	Nop::
	Exec:Tin:N:rtin:
	Nop:Tin is an easy to use, menu based news reader.:
	Nop:Type `h` for help within the program.:
	Exit:Exit this menu:
EndMenu

Menu Web
	Title:"Surf" the World Wide Web:
	Nop::
	Exec:Lynx:N:lynx -noprint -restrictions=editor,file_url,exec,shell:
	Exit:Exit this menu:
EndMenu

Menu Top Left Offset 2 -1 Password "tY30PCrOhbICLLXA6z3pTVs" Admin
	Title:Account Administration:
	Nop::
	Exec:Change Finger Information:/usr/bin/chfn:
	Exec:Start up tcsh:/bin/tcsh:
	Args:Run any command::Enter command to run:
	Nop::
	Exit:Exit This Menu:
EndMenu

Menu Bottom Left Offset 0 -1 HotKeys
	Title:Global HotKeys:
	Nop::
	Exec:p Pine:NKp:pine:
	Args:f Finger:PKf:finger:Who do you want to finger:
	Args:w W:PKw:w:Who do want to look for:
	Args:l Last:Kl:last -20:Enter optional username:
	Exec:e Elm:NKe:elm:
	Args:t Telnet:Kt:telnet:Enter host and optional port:
	Exec:b rBash:NKb:bash -version:
	Nop::
	Exit:Back to last menu:
EndMenu

RCBlock System
	restrict all except pause

	# Turn on exec logging
	set logging

	# Set Mail notification with timeout 5 sec
	set mailnotify 5

	# System Backgrounds
	set background system.bg.1:system.bg.2:system.bg.2a

	# Turn on TOP_BAR clock
	set barclock

	# Pager to use when an exec/args menu item has a P flag
	set execpager "less -E -P'Press Space to continue'"

	# Lock screen - saver frame timeout (ms) and backdoor password
	set lockscreensaver 80
	set lockbackdoor "tY30PCrOhbICLLXA6z3pTVs"
EndRCBlock

RCFile System Login system.flash
RCFile .

GRIPES

The way the menu token fields are handled is horrible. This man page is even worse. Anyone want to volunteer a nicer one.

BUGS

No! No! Never! Yes. A bit. She has got a fart.

The current release has some built in limits on line length etc.

AUTHOR

Stephen Fegan (steve@netsoc.ucd.ie)

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