Learning the bash Shell 2nd Edition [Electronic resources] نسخه متنی

D.2 BNF for bash

The following is the syntax of bash 2.0 in Backus-Naur Form (BNF):

<letter> ::= a|b|c|d|e|f|g|h|i|j|k|l|m|n|o|p|q|r|s|t|u|v|w|x|y|z|

 A|B|C|D|E|F|G|H|I|J|K|L|M|N|O|P|Q|R|S|T|U|V|W|X|Y|Z

<digit> ::= 0|1|2|3|4|5|6|7|8|9

<number> ::= <digit>

 | <number> <digit>

<word> ::= <letter>

 | <word> <letter>

 | <word> '_'

<word_list> ::= <word>

 | <word_list> <word>

<assignment_word> ::= <word> '=' <word>

<redirection> ::= '>' <word>

 | '<' <word>

 | <number> '>' <word>

 | <number> '<' <word>

 | '>>' <word>

 | <number> '>>' <word>

 | '<<' <word>

 | <number> '<<' <word>

 | '<&' <number>

 | <number> '<&' <number>

 | '>&' <number>

 | <number> '>&' <number>

 | '<&' <word>

 | <number> '<&' <word>

 | '>&' <word>

 | <number> '>&' <word>

 | '<<-' <word>

 | <number> '<<-' <word>

 | '>&' '-'

 | <number> '>&' '-'

 | '<&' '-'

 | <number> '<&' '-'

 | '&>' <word>

 | <number> '<>' <word>

 | '<>' <word>

 | '>|' <word>

 | <number> '>|' <word>

<simple_command_element> ::= <word>

 | <assignment_word>

 | <redirection>

<redirection_list> ::= <redirection>

 | <redirection_list> <redirection>

<simple_command> ::= <simple_command_element>

 | <simple_command> <simple_command_element>

<command> ::= <simple_command>

 | <shell_command>

 | <shell_command> <redirection_list>

<shell_command> ::= <for_command>

 | <case_command>

 | while <compound_list> do <compound_list> done

 | until <compound_list> do <compound_list> done

 | <select_command>

 | <if_command>

 | <subshell>

 | <group_command>

 | <function_def>

<for_command> ::= for <word> <newline_list> do <compound_list> done

 | for <word> <newline_list> '{' <compound_list> '}'

 | for <word> ';' <newline_list> do <compound_list> done

 | for <word> ';' <newline_list> '{' <compound_list> '}'

 | for <word> <newline_list> in <word_list> <list_terminator>

 <newline_list> do <compound_list> done

 | for <word> <newline_list> in <word_list> <list_terminator>

 <newline_list> '{' <compound_list> '}'

<select_command> ::= select <word> <newline_list> do <list> done

 | select <word> <newline_list> '{' <list> '}'

 | select <word> ';' <newline_list> do <list> done

 | select <word> ';' <newline_list> '{' list '}'

 | select <word> <newline_list> in <word_list>

 <list_terminator> <newline_list> do <list> done

 | select <word> <newline_list> in <word_list>

 <list_terminator> <newline_list> '{' <list> '}'

<case_command> ::= case <word> <newline_list> in <newline_list> esac

 | case <word> <newline_list> in <case_clause_sequence>

 <newline_list> esac

 | case <word> <newline_list> in <case_clause> esac

<function_def> ::= <word> '(' ')' <newline_list> <group_command>

 | function <word> '(' ')' <newline_list> <group_command>

 | function <word> <newline_list> <group_command>

<subshell> ::= '(' <compound_list> ')'

<if_command> ::= if <compound_list> then <compound_list> fi

 | if <compound_list> then <compound_list> else <compound_list> fi

 | if <compound_list> then <compound_list> <elif_clause> fi

<group_command> ::= '{' <list> '}'

<elif_clause> ::= elif <compound_list> then <compound_list>

 | elif <compound_list> then <compound_list> else <compound_list>

 | elif <compound_list> then <compound_list> <elif_clause>

<case_clause> ::= <pattern_list>

 | <case_clause_sequence> <pattern_list>

<pattern_list> ::= <newline_list> <pattern> ')' <compound_list>

 | <newline_list> <pattern> ')' <newline_list>

 | <newline_list> '(' <pattern> ')' <compound_list>

 | <newline_list> '(' <pattern> ')' <newline_list>

<case_clause_sequence> ::= <pattern_list> ';;'

 | <case_clause_sequence> <pattern_list> ';;'

<pattern> ::= <word>

 | <pattern> '|' <word>

<list> ::= <newline_list> <list0>

<compound_list> ::= <list>

 | <newline_list> <list1>

<list0> ::= <list1> '\n' <newline_list>

 | <list1> '&' <newline_list>

 | <list1> ';' <newline_list>

<list1> ::= <list1> '&&' <newline_list> <list1>

 | <list1> '||' <newline_list> <list1>

 | <list1> '&' <newline_list> <list1>

 | <list1> ';' <newline_list> <list1>

 | <list1> '\n' <newline_list> <list1>

 | <pipeline_command>

<list_terminator> ::= '\n'

 | ';'

<newline_list> ::=

 | <newline_list> '\n'

<simple_list> ::= <simple_list1>

 | <simple_list1> '&'

 | <simple_list1> ';'

<simple_list1> ::= <simple_list1> '&&' <newline_list> <simple_list1>

 | <simple_list1> '||' <newline_list> <simple_list1>

 | <simple_list1> '&' <simple_list1>

 | <simple_list1> ';' <simple_list1>

 | <pipeline_command>

<pipeline_command> ::= <pipeline>

 | '!' <pipeline>

 | <timespec> <pipeline>

 | <timespec> '!' <pipeline>

 | '!' <timespec> <pipeline>

<pipeline> ::=

 <pipeline> '|' <newline_list> <pipeline>

 | <command>

<time_opt> ::= '-p'

<timespec> ::= time

 | time <time_opt>

.XE "BNF (Backus-Naur Form)"

.XE "bash" "syntax, BNF form of"