NAME
regexp - Match a regular expression against a string
SYNOPSIS
regexp ?switches? exp string ?matchVar? ?subMatchVar sub
MatchVar ...?
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DESCRIPTION
Determines whether the regular expression exp matches part
or all of string and returns 1 if it does, 0 if it
doesn't, unless -inline is specified (see below). (Regu
lar expression matching is described in the re_syntax ref
erence page.)
If additional arguments are specified after string then
they are treated as the names of variables in which to
return information about which part(s) of string matched
exp. MatchVar will be set to the range of string that
matched all of exp. The first subMatchVar will contain
the characters in string that matched the leftmost paren
thesized subexpression within exp, the next subMatchVar
will contain the characters that matched the next paren
thesized subexpression to the right in exp, and so on.
If the initial arguments to regexp start with - then they
are treated as switches. The following switches are cur
rently supported:
-about Instead of attempting to match the regular
expression, returns a list containing
information about the regular expression.
The first element of the list is a subex
pression count. The second element is a
list of property names that describe vari
ous attributes of the regular expression.
This switch is primarily intended for
debugging purposes.
-expanded Enables use of the expanded regular expres
sion syntax where whitespace and comments
are ignored. This is the same as specify
ing the (?x) embedded option (see METASYN
TAX, below).
-indices Changes what is stored in the subMatchVars.
Instead of storing the matching characters
from string, each variable will contain a
list of two decimal strings giving the
indices in string of the first and last
ters.
-line Enables newline-sensitive matching. By
default, newline is a completely ordinary
character with no special meaning. With
this flag, `[^' bracket expressions and `.'
never match newline, `^' matches an empty
string after any newline in addition to its
normal function, and `$' matches an empty
string before any newline in addition to
its normal function. This flag is equiva
lent to specifying both -linestop and -lin
eanchor, or the (?n) embedded option (see
METASYNTAX, below).
-linestop Changes the behavior of `[^' bracket
expressions and `.' so that they stop at
newlines. This is the same as specifying
the (?p) embedded option (see METASYNTAX,
below).
-lineanchor Changes the behavior of `^' and `$' (the
``anchors'') so they match the beginning
and end of a line respectively. This is
the same as specifying the (?w) embedded
option (see METASYNTAX, below).
-nocase Causes upper-case characters in string to
be treated as lower case during the match
ing process. |
-all ||
Causes the regular expression to be matched |
as many times as possible in the string, |
returning the total number of matches |
found. If this is specified with match |
variables, they will continue information |
for the last match only. |
-inline ||
Causes the command to return, as a list, |
the data that would otherwise be placed in |
match variables. When using -inline, match |
variables may not be specified. If used |
with -all, the list will be concatenated at |
each iteration, such that a flat list is |
always returned. For each match iteration, |
the command will append the overall match |
data, plus one element for each subexpres |
sion in the regular expression. Examples |
are: |
regexp -inline -- {\w(\w)} " inlined " |
=> {in n} |
=> {in n li i ne e} |
-start |
index ||
Specifies a character index offset into the |
string to start matching the regular |
expression at. When using this switch, `^' |
will not match the beginning of the line, |
and \A will still match the start of the |
string at index. If -indices is specified, |
the indices will be indexed starting from |
the absolute beginning of the input string. |
index will be constrained to the bounds of |
the input string.
-- Marks the end of switches. The argument
following this one will be treated as exp
even if it starts with a -.
If there are more subMatchVar's than parenthesized subex
pressions within exp, or if a particular subexpression in
exp doesn't match the string (e.g. because it was in a
portion of the expression that wasn't matched), then the
corresponding subMatchVar will be set to ``-1 -1'' if
-indices has been specified or to an empty string other
wise.
SEE ALSO
re_syntax(n), regsub(n)
KEYWORDS
match, regular expression, string
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