regex(1F) UNIX System V(Form and Menu Language Interpreter Utilities) regex(1F)


NAME
      regex - match patterns against a string

SYNOPSIS
      regex [-e] [-v "string"] [pattern template] ... pattern [template]

DESCRIPTION
      The regex command takes a string from stdin, and a list of
      pattern/template pairs, and runs regex(3X) to compare the string against
      each pattern until there is a match.  When a match occurs, regex writes
      the corresponding template to stdout and returns TRUE.  The last (or
      only) pattern does not need a template.  If that is the pattern that
      matches the string, the function simply returns TRUE.  If no match is
      found, regex returns FALSE.

      -e        means regex will evaluate the corresponding template and write
                the result to stdout.

      -v "string"
                If -v is specified, string will be used instead of stdin to
                match against patterns.

      The argument pattern is a regular expression of the form described in
      regex(3X).  In most cases pattern should be enclosed in single quotes to
      turn off special meanings of characters.  Note that only the final
      pattern in the list may lack a template.

      The argument template may contain the strings $m0 through $m9, which will
      be expanded to the part of pattern enclosed in ( ... )$0 through ( ...
      )$9 constructs (see examples below).  Note that if you use this feature,
      you must be sure to enclose template in single quotes so that FMLI
      doesn't expand $m0 through $m9 at parse time.  This feature gives regex
      much of the power of cut(1), paste(1), and grep(1), and some of the
      capabilities of sed(1).  If there is no template, the default is
      "$m0$m1$m2$m3$m4$m5$m6$m7$m8$m9".

EXAMPLES
      To cut the 4th through 8th letters out of a string (this example will
      output strin and return TRUE):

            `regex -v "my string is nice" '^.{3}(.{5})$0' '$m0'`

      In a form, to validate input to field 5 as an integer:

            valid=`regex -v "$F5" '^[0-9]+$'`

      In a form, to translate an environment variable which contains one of the
      numbers 1, 2, 3, 4, 5 to the letters a, b, c, d, e:

            value=`regex -v "$VAR1" 1 a 2 b 3 c 4 d 5 e '.*' 'Error'`




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regex(1F) UNIX System V(Form and Menu Language Interpreter Utilities) regex(1F)


      Note the use of the pattern '.*' to mean ``anything else.''

      In the example below, all three lines constitute a single backquoted
      expression.  This expression, by itself, could be put in a menu
      definition file.  Since backquoted expressions are expanded as they are
      parsed, and output from a backquoted expression (the cat command, in this
      example) becomes part of the definition file being parsed, this
      expression would read /etc/passwd and make a dynamic menu of all the
      login ids on the system.

            `cat /etc/passwd | regex '^([^:]*)$0.*$' '
            name=$m0
            action=`message "$m0 is a user"`'`

DIAGNOSTICS
      If none of the patterns matches, regex returns FALSE, otherwise TRUE.

NOTES
      Patterns and templates must often be enclosed in single quotes to turn
      off the special meanings of characters.  Especially if you use the $m0
      through $m9 variables in the template, since FMLI will expand the
      variables (usually to "") before regex even sees them.

      Single characters in character classes (inside []) must be listed before
      character ranges, otherwise they will not be recognized.  For example,
      [a-zA-Z/] will not find underscores () or slashes (/), but [/a-zA-Z]
      will.

      The regular expressions accepted by regcmp differ slightly from other
      utilities (that is, sed, grep, awk, ed, and so on).

      regex with the -e option forces subsequent commands to be ignored.  In
      other words if a backquoted statement appears as follows:

            `regex -e ...; command1; command2`

      command1 and command2 would never be executed.  However, dividing the
      expression into two:

            `regex -e ...``command1; command2`

      would yield the desired result.

SEE ALSO
      regcmp(3), regex(3X) in the UNIX System V Programmer's Reference Manual
      awk(1), cut(1), grep(1), paste(1), sed(1) in the UNIX System V User's
      Reference Manual







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