Appendix D. Syntax

D.2 BNF for bash

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

<letter> ::= abcdefghijklmnopqrstuvwxyz

ABCDEFGHIJKLMNOPQRSTUVWXYZ

<digit> ::= 0123456789

<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"