EMail comments to: <dick@csci.csusb.edu>

The objectives of this notation aredefined in the MATHS manifesto.

Also see the introductions, the overview, the description of the notations(like '::=', '#(_)', 'O(_)', '|', '&', etc), more samples, and a draft formal definition.

See my home page for information on other formal notations and methods.

Contents

• Index
• Signature

/u/faculty/dick/cs320/math.comp.ascii

|- white_space::= SP | HT | ...

doublequote::=

"\"", quote:="'", backquote::="`", backslash::="\\".

SYNTAX

The Bourne shell a pure interpreter for a highly interactive, complex and powerful programming language with syntax based loosely on ALGOL 68. The basic input (from a user or from a file) into the interpreter (sh) is a sequence of pipelined commands.

pipeline::=

command (input_redirection|) #("|" command) ("|" command output_redirction|).

input_redirection::=

"<" file | "<<"string.

output_redirection::=

( ">" | ">>" ) file.

command::=

command_name #(separator argument), Normally, separator::=whitespace #whitespace.

argument::=

#(word | string | escaped_symbol ),

word::=

#(value_shell_variable| value_of_argument | #(char~separator)),

A script is a sequence of commands and control structures separated by command separators

script::=

(command | built_in_structure) #(command_separator (command | built_in_structure)),

command_separator::=

EOLN #whitespace | semicolon #whitspace.

built_in_structure::=

assignment | selection | loop | other_command,

selection::=

if_then_fi | case_esac,

loop::=

for_do_done | while_do_done | ... .

other_command::=

exit_statement | echo_statement |... .

A shell variable is identified by an identifier:

shell_variable::=

identifier,

value_of_variable::=

"$" variable| "${" identifier operator word "}", The "${...}" form is left undefined.

Arguments are numbered inside a shell script:

script_argument::=

digit,

value_of_argument::=

"$"digit.

There are several special variables/values:

value::=

value_of_argument | value_of_variable | "$" ( "$" | "?" | "#" | "!" |

..).

string::=

double_quoted_string |single_quoted_string|reverse_quoted_string,

escaped_symbol::=

backslash char,

double_quoted_string::=

double_quote #( value_of_variable | value_of_argument | #(char~double_quote) | escaped_symbol) double_quote,

reverse_quoted_string::=

backquote pipeline backquote,

single_quoted_string::=

quote #(char~quote | escaped_symbol) quote.

• argument
• built_in_structure
• command
• command_separator
• double_quoted_string
• doublequote
• escaped_symbol
• input_redirection
• loop
• other_command
• output_redirection
• pipeline
• reverse_quoted_string
• script
• script_argument
• selection
• shell_variable
• single_quoted_string
• string
• value
• value_of_argument
• value_of_variable
• word