svcadm(1M)을 검색하려면 섹션에서 1M 을 선택하고, 맨 페이지 이름에 svcadm을 입력하고 검색을 누른다.
regexp(7)
Standards, Environments, Macros, Character Sets, and miscellany
regexp(7)
NAME
regexp, compile, step, advance - simple regular expression compile and
match routines
SYNOPSIS
#define INIT declarations
#define GETC(void) getc code
#define PEEKC(void) peekc code
#define UNGETC(c) ungetc code
#define RETURN(ptr) return code
#define ERROR(val) error code
extern char *loc1, *loc2, *locs;
#include <regexp.h>
char *compile(char *instring, char *expbuf, const char *endfug, int eof);
int step(const char *string, const char *expbuf);
int advance(const char *string, const char *expbuf);
DESCRIPTION
Regular Expressions (REs) provide a mechanism to select specific
strings from a set of character strings. The Simple Regular Expressions
described below differ from the Internationalized Regular Expressions
described on the regex(7) manual page in the following ways:
o only Basic Regular Expressions are supported
o the Internationalization features—character class, equiva‐
lence class, and multi-character collation—are not sup‐
ported.
The functions step(), advance(), and compile() are general purpose reg‐
ular expression matching routines to be used in programs that perform
regular expression matching. These functions are defined by the <reg‐
exp.h> header.
The functions step() and advance() do pattern matching given a charac‐
ter string and a compiled regular expression as input.
The function compile() takes as input a regular expression as defined
below and produces a compiled expression that can be used with step()
or advance().
Basic Regular Expressions
A regular expression specifies a set of character strings. A member of
this set of strings is said to be matched by the regular expression.
Some characters have special meaning when used in a regular expression;
other characters stand for themselves.
The following one-character REs match a single character:
1.1 An ordinary character (not one of those discussed in 1.2 below)
is a one-character RE that matches itself.
1.2 A backslash (\) followed by any special character is a one-char‐
acter RE that matches the special character itself. The special
characters are:
a. ., *, [, and \ (period, asterisk, left square bracket, and
backslash, respectively), which are always special, except
when they appear within square brackets ([]; see 1.4
below).
b. ^ (caret or circumflex), which is special at the beginning
of an entire RE (see 4.1 and 4.3 below), or when it imme‐
diately follows the left of a pair of square brackets ([])
(see 1.4 below).
c. $ (dollar sign), which is special at the end of an entire
RE (see 4.2 below).
d. The character used to bound (that is, delimit) an entire
RE, which is special for that RE (for example, see how
slash (/) is used in the g command, below.)
1.3 A period (.) is a one-character RE that matches any character
except new-line.
1.4 A non-empty string of characters enclosed in square brackets
([]) is a one-character RE that matches any one character in
that string. If, however, the first character of the string is a
circumflex (^), the one-character RE matches any character
except new-line and the remaining characters in the string. The
^ has this special meaning only if it occurs first in the
string. The minus (−) may be used to indicate a range of consec‐
utive characters; for example, [0−9] is equivalent to
[0123456789]. The − loses this special meaning if it occurs
first (after an initial ^, if any) or last in the string. The
right square bracket (]) does not terminate such a string when
it is the first character within it (after an initial ^, if
any); for example, []a−f] matches either a right square bracket
(]) or one of the ASCII letters a through f inclusive. The four
characters listed in 1.2.a above stand for themselves within
such a string of characters.
The following rules may be used to construct REs from one-character
REs:
2.1 A one-character RE is a RE that matches whatever the one-charac‐
ter RE matches.
2.2 A one-character RE followed by an asterisk (*) is a RE that
matches 0 or more occurrences of the one-character RE. If there
is any choice, the longest leftmost string that permits a match
is chosen.
2.3 A one-character RE followed by \{m\}, \{m,\}, or \{m,n\} is a RE
that matches a range of occurrences of the one-character RE. The
values of m and n must be non-negative integers less than 256;
\{m\} matches exactly m occurrences; \{m,\} matches at least m
occurrences; \{m,n\} matches any number of occurrences between
m and n inclusive. Whenever a choice exists, the RE matches as
many occurrences as possible.
2.4 The concatenation of REs is a RE that matches the concatenation
of the strings matched by each component of the RE.
2.5 A RE enclosed between the character sequences \( and \) is a RE
that matches whatever the unadorned RE matches.
2.6 The expression \n matches the same string of characters as was
matched by an expression enclosed between \( and \) earlier in
the same RE. Here n is a digit; the sub-expression specified is
that beginning with the n-th occurrence of \( counting from the
left. For example, the expression ^\(.*\)\1$ matches a line con‐
sisting of two repeated appearances of the same string.
An RE may be constrained to match words.
3.1 \< constrains a RE to match the beginning of a string or to fol‐
low a character that is not a digit, underscore, or letter. The
first character matching the RE must be a digit, underscore, or
letter.
3.2 \> constrains a RE to match the end of a string or to precede a
character that is not a digit, underscore, or letter.
An entire RE may be constrained to match only an initial segment or
final segment of a line (or both).
4.1 A circumflex (^) at the beginning of an entire RE constrains
that RE to match an initial segment of a line.
4.2 A dollar sign ($) at the end of an entire RE constrains that RE
to match a final segment of a line.
4.3 The construction ^entire RE$ constrains the entire RE to match
the entire line.
The null RE (for example, //) is equivalent to the last RE encountered.
Addressing with REs
Addresses are constructed as follows:
1. The character "." addresses the current line.
2. The character "$" addresses the last line of the buffer.
3. A decimal number n addresses the n-th line of the buffer.
4. 'x addresses the line marked with the mark name character x,
which must be an ASCII lowercase letter (a-z). Lines are
marked with the k command described below.
5. A RE enclosed by slashes (/) addresses the first line found
by searching forward from the line following the current
line toward the end of the buffer and stopping at the first
line containing a string matching the RE. If necessary, the
search wraps around to the beginning of the buffer and con‐
tinues up to and including the current line, so that the
entire buffer is searched.
6. A RE enclosed in question marks (?) addresses the first line
found by searching backward from the line preceding the cur‐
rent line toward the beginning of the buffer and stopping at
the first line containing a string matching the RE. If nec‐
essary, the search wraps around to the end of the buffer and
continues up to and including the current line.
7. An address followed by a plus sign (+) or a minus sign (−)
followed by a decimal number specifies that address plus
(respectively minus) the indicated number of lines. A short‐
hand for .+5 is .5.
8. If an address begins with + or −, the addition or subtrac‐
tion is taken with respect to the current line; for example,
−5 is understood to mean .−5.
9. If an address ends with + or −, then 1 is added to or sub‐
tracted from the address, respectively. As a consequence of
this rule and of Rule 8, immediately above, the address −
refers to the line preceding the current line. (To maintain
compatibility with earlier versions of the editor, the char‐
acter ^ in addresses is entirely equivalent to −.) Moreover,
trailing + and − characters have a cumulative effect, so −−
refers to the current line less 2.
10. For convenience, a comma (,) stands for the address pair
1,$, while a semicolon (;) stands for the pair .,$.
Characters With Special Meaning
Characters that have special meaning except when they appear within
square brackets ([]) or are preceded by \ are: ., *, [, \. Other spe‐
cial characters, such as $ have special meaning in more restricted con‐
texts.
The character ^ at the beginning of an expression permits a successful
match only immediately after a newline, and the character $ at the end
of an expression requires a trailing newline.
Two characters have special meaning only when used within square brack‐
ets. The character − denotes a range, [c−c], unless it is just after
the open bracket or before the closing bracket, [−c] or [c−] in which
case it has no special meaning. When used within brackets, the charac‐
ter ^ has the meaning complement of if it immediately follows the open
bracket (example: [^c]); elsewhere between brackets (example: [c^]) it
stands for the ordinary character ^.
The special meaning of the \ operator can be escaped only by preceding
it with another \, for example \\.
Macros
Programs must have the following five macros declared before the
#include <regexp.h> statement. These macros are used by the compile()
routine. The macros GETC, PEEKC, and UNGETC operate on the regular
expression given as input to compile().
GETC This macro returns the value of the next character
(byte) in the regular expression pattern. Successive
calls to GETC should return successive characters of
the regular expression.
PEEKC This macro returns the next character (byte) in the
regular expression. Immediately successive calls to
PEEKC should return the same character, which should
also be the next character returned by GETC.
UNGETC This macro causes the argument c to be returned by the
next call to GETC and PEEKC. No more than one character
of pushback is ever needed and this character is guar‐
anteed to be the last character read by GETC. The
return value of the macro UNGETC(c) is always ignored.
RETURN(ptr) This macro is used on normal exit of the compile() rou‐
tine. The value of the argument ptr is a pointer to the
character after the last character of the compiled reg‐
ular expression. This is useful to programs which have
memory allocation to manage.
ERROR(val) This macro is the abnormal return from the compile()
routine. The argument val is an error number (see
ERRORS below for meanings). This call should never
return.
compile()
The syntax of the compile() routine is as follows:
compile(instring, expbuf, endbuf, eof)
The first parameter, instring, is never used explicitly by the com‐
pile() routine but is useful for programs that pass down different
pointers to input characters. It is sometimes used in the INIT declara‐
tion (see below). Programs which call functions to input characters or
have characters in an external array can pass down a value of (char *)0
for this parameter.
The next parameter, expbuf, is a character pointer. It points to the
place where the compiled regular expression will be placed.
The parameter endbuf is one more than the highest address where the
compiled regular expression may be placed. If the compiled expression
cannot fit in (endbuf−expbuf) bytes, a call to ERROR(50) is made.
The parameter eof is the character which marks the end of the regular
expression. This character is usually a /.
Each program that includes the <regexp.h> header file must have a
#define statement for INIT. It is used for dependent declarations and
initializations. Most often it is used to set a register variable to
point to the beginning of the regular expression so that this register
variable can be used in the declarations for GETC, PEEKC, and UNGETC.
Otherwise it can be used to declare external variables that might be
used by GETC, PEEKC and UNGETC. (See EXAMPLES below.)
step(), advance()
The first parameter to the step() and advance() functions is a pointer
to a string of characters to be checked for a match. This string should
be null terminated.
The second parameter, expbuf, is the compiled regular expression which
was obtained by a call to the function compile().
The function step() returns non-zero if some substring of string
matches the regular expression in expbuf and 0 if there is no match. If
there is a match, two external character pointers are set as a side
effect to the call to step(). The variable loc1 points to the first
character that matched the regular expression; the variable loc2 points
to the character after the last character that matches the regular
expression. Thus if the regular expression matches the entire input
string, loc1 will point to the first character of string and loc2 will
point to the null at the end of string.
The function advance() returns non-zero if the initial substring of
string matches the regular expression in expbuf. If there is a match,
an external character pointer, loc2, is set as a side effect. The vari‐
able loc2 points to the next character in string after the last charac‐
ter that matched.
When advance() encounters a * or \{ \} sequence in the regular expres‐
sion, it will advance its pointer to the string to be matched as far as
possible and will recursively call itself trying to match the rest of
the string to the rest of the regular expression. As long as there is
no match, advance() will back up along the string until it finds a
match or reaches the point in the string that initially matched the *
or \{ \}. It is sometimes desirable to stop this backing up before the
initial point in the string is reached. If the external character
pointer locs is equal to the point in the string at sometime during the
backing up process, advance() will break out of the loop that backs up
and will return zero.
The external variables circf, sed, and nbra are reserved.
EXAMPLES
Example 1 Using Regular Expression Macros and Calls
The following is an example of how the regular expression macros and
calls might be defined by an application program:
#define INIT register char *sp = instring;
#define GETC() (*sp++)
#define PEEKC() (*sp)
#define UNGETC(c) (−−sp)
#define RETURN(c) return;
#define ERROR(c) regerr()
#include <regexp.h>
. . .
(void) compile(*argv, expbuf, &expbuf[ESIZE],'\0');
. . .
if (step(linebuf, expbuf))
succeed;
DIAGNOSTICS
The function compile() uses the macro RETURN on success and the macro
ERROR on failure (see above). The functions step() and advance() return
non-zero on a successful match and zero if there is no match. Errors
are:
11 range endpoint too large.
16 bad number.
25 \ digit out of range.
36 illegal or missing delimiter.
41 no remembered search string.
42 \( \) imbalance.
43 too many \(.
44 more than 2 numbers given in \{ \}.
45 } expected after \.
46 first number exceeds second in \{ \}.
49 [ ] imbalance.
50 regular expression overflow.
SEE ALSO
regex(7)
Oracle Solaris 11.4 11 May 2021 regexp(7)