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regcmp(3)
NAME
  regcmp, regex - Compile and execute regular expression

SYNOPSIS
  #include <libgen.h>

  char *regcmp(
	  const char *string1,
	  ... /*,
	  (char *)0 */ );

  char *regex(
	  const char *re,
	  const char *subject,
	  ... );

LIBRARY
  Standard C Library (libc)

STANDARDS
  Interfaces documented on this reference page conform to industry standards
  as follows:

  regcmp(), regex():  XPG4-UNIX

  Refer to the standards(5) reference page for more information about
  industry standards and associated tags.

PARAMETERS
  string1
      Points to the string that is to be matched or converted.

  re  Points to a compiled regular expression string.

  subject
      Points to the string that is to be matched against re.

DESCRIPTION
  The regcmp() function compiles a regular expression consisting of the
  concatenated arguments and returns a pointer to the compiled form. The end
  of arguments is indicated by a null pointer. The malloc() function is used
  to create space for the compiled form. It is the responsibility of the
  process to free unneeded space so allocated. A null pointer returned from
  regcmp() indicates an invalid argument.

  The regex() function executes a compiled pattern against the subject
  string. Additional arguments of type char must be passed to receive matched
  subexpressions back. A global character pointer, __loc1, points to the
  first matched character in the subject string.

  The regcmp() and regex() functions support the simple regular expressions
  which are defined in the grep(1) reference page, but the syntax and
  semantics are slightly different. The following are the valid symbols and
  their associated meanings:

  [] * . ^
      The left and right bracket, asterisk, period, and circumflex symbols
      retain their meanings as defined in the grep(1) reference page.

  $   A dollar sign matches the end of the string; \n matches a new line.

  -   Used within brackets, the hyphen signifies an ASCII character range.
      For example [a-z] is equivalent to [abcd...xyz]. The - (hyphen) can
      represent itself only if used as the first or last character.  For
      example, the character class expression []-] matches the characters ]
      (right bracket) and - (hyphen).

  +   A regular expression followed by a + (plus sign) means one or more
      times. For example, [0-9]+ is equivalent to [0-9][0-9]*.

  {m} {m,} {m,u}
      Integer values enclosed in {} braces indicate the number of times the
      preceding regular expression can be applied. The value m is the minimum
      number and u is a number, less than 256, which is the maximum. The
      syntax {m} indicates the exact number of times the regular expression
      can be applied. The syntax {m,} is analogous to {m,infinity}. The +
      (plus sign) and * (asterisk) operations are equivalent to {1,} and
      {0,}, respectively.

  (...)$n
      The value of the enclosed regular expression is returned.	 The value is
      stored in the (n+1)th argument following the subject argument.  A
      maximum of ten enclosed regular expressions are allowed. The regex()
      function makes its assignments unconditionally.

  (...)
      Parentheses are used for grouping. An operator, such as *, +, or {},
      can work on a single character or a regular expression enclosed in
      parentheses. For example, (a*(cb+)*)$0.

  Since all of the symbols defined above are special characters, they must be
  escaped to be used as themselves.

NOTES
  The regcmp() and regex() interfaces are scheduled to be withdrawn from a
  future version of the X/Open CAE Specification.

  These interfaces are obsolete; they are guaranteed to function properly
  only in the C/POSIX locale and so should be avoided. Use the POSIX
  regcomp() interface instead of regcmp() and regex().

RETURN VALUES
  Upon successful completion, the regcmp() function returns a pointer to the
  compiled regular expression. Otherwise, a null pointer is returned and
  errno may be set to indicate the error.

  Upon successful completion, the regex() function returns a pointer to the
  next unmatched character in the subject string. Otherwise, a null pointer
  is returned.

SEE ALSO
  Commands: grep(1)

  Functions: malloc(3), regcomp(3)

  Standards: standards(5)

Index for Section 3

Alphabetical listing for R

Top of page