bareword_char      = @{ !("|" | ";" | "\"" | "'" | WHITESPACE | COMMENT) ~ ANY }
single_string_char = @{ "\\'" | (!"'" ~ ANY) }
double_string_char = @{ "\\\"" | (!"\"" ~ ANY) }

redir_prefix  = @{ ASCII_DIGIT* ~ (">>" | ">" | "<") ~ WHITESPACE* }
bareword      = @{ bareword_char+ }
single_string = @{ single_string_char+ }
double_string = @{ double_string_char+ }

word     = ${
    redir_prefix? ~
    (bareword |
    "'" ~ single_string ~ "'" |
    "\"" ~ double_string ~ "\"")
}

exe      = ${ word ~ (w ~ word)* }
pipeline = ${ exe ~ (w ~ "|" ~ w ~ exe)* }
commands = ${ pipeline ~ (w ~ ";" ~ w ~ pipeline)* }

line = ${ SOI ~ w ~ commands ~ w ~ EOI }

w          = _{ (WHITESPACE | COMMENT)* }
WHITESPACE = _{ (" " | "\t" | "\n") }
COMMENT    = _{ "#" ~ ANY* }