SH-REGEX(1)SH-REGEX(1)NAME
re, match - shell script regular expression handling
SYNOPSIS
load regex
match regex [ arg... ]
${re op arg... }
DESCRIPTION
Regex is a loadable module for sh(1) that provides access to regular-
expression pattern matching and substitution. For details of regular
expression syntax in Inferno, see regexp(6). Regex defines one builtin
command, match, and one builtin substitution operator, re. Match gives
a false exit status if its argument regex fails to match any arg. Re
provides several operations, detailed below:
${re g regexp [ arg...]}
Yields a list of each arg that matches regexp.
${re v regexp [ arg...]}
Yields a list of each arg that does not match regexp.
${re m regexp arg}
Yields the portion of arg that matches regexp, or an empty
list if there was no match.
${re M regexp arg}
Yields a list consisting of the portion of arg that matches
regexp, followed by list elements giving the portion of arg
that matched each parenthesized subexpression in turn.
${re mg regexp arg}
Similar to re m except that it applies the match consecu‐
tively through arg, yielding a list of all the portions of
arg that match regexp. If a match is made to the null
string, no subsequent substitutions will take place.
${re s regexp subs [ arg... ]}
For each arg, re s substitutes the first occurrence of regexp
(if any) by subs. If subs contains a sequence of the form \d
where d is a single decimal digit, the dth parenthesised sub‐
expression in regexp will be substituted in its place. \0 is
substituted by the entire match. If any other character fol‐
lows a backslash (\), that character will be substituted.
Arguments which contain no match to regexp will be left
unchanged.
${re sg regexp subs [ arg... ]}
Similar to re s except that all matches of regexp within each
arg will be substituted for, rather than just the first
match. Only one occurrence of the null string is substituted.
EXAMPLES
List all files in the current directory that end in .dis or .sbl:
ls -l ${re g '\.(sbl|dis)$' *}
Break string up into its constituent characters, putting the result in
shell variable x:
x = ${re mg '.|\n' string}
Quote a string s so that it can be used as a literal regular expression
without worrying about metacharacters:
s = ${re sg '[*|[\\+.^$()?]' '\\\0' $s}
Define a substitution function pat2regexp to convert shell-style pat‐
terns into equivalent regular expressions (e.g. ``?.sbl*'' would
become ``^.\.sbl.*$''):
load std
subfn pat2regexp {
result = '^' ^ ${re sg '\*' '.*'
${re sg ' ${re sg '[()+\\.^$|]' '\\\0' $*}
}
} ^ '$'
}
SOURCE
/appl/cmd/sh/regex.b
SEE ALSOregexp(6), regex(2), sh(1), string(2), sh-std(1)SH-REGEX(1)
