regex(1F) FMLI Commands regex(1F)
regex - match patterns against a string
regex [-e] [ -v "string"] [ pattern template] ... pattern [template]
The regex command takes a string from the standard input, and a list of
pattern / template pairs, and runs regex() to compare the string
against each pattern until there is a match. When a match occurs,
regex writes the corresponding template to the standard output 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.
The argument pattern is a regular expression of the form described in
regex(). In most cases, pattern should be enclosed in single quotes to
turn off special meanings of characters. Note that only the final pat-
tern 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 does not 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.
The following options are supported:
-e Evaluates the corresponding template and writes the result to the
standard output.
-v "string"
Uses string instead of the standard input to match against pat-
terns.
Example 1: Cutting letters out of a string
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'`
Example 2: Validating input in a form
In a form, to validate input to field 5 as an integer:
valid=`regex -v "$F5" '^[0-9]+$'`
Example 3: Translating an environment variable in a form
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'`
Note the use of the pattern '.*' to mean "anything else".
Example 4: Using backquoted expressions
In the example below, all three lines constitute a single backquoted
expression. This expression, by itself, could be put in a menu defini-
tion 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"`'`
If none of the patterns match, regex returns FALSE, otherwise TRUE.
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 vari-
ables (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 forth).
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 attributes(5) for descriptions of the following attributes:
+-----------------------------+-----------------------------+
| ATTRIBUTE TYPE | ATTRIBUTE VALUE |
+-----------------------------+-----------------------------+
|Availability |SUNWcsu |
+-----------------------------+-----------------------------+
awk(1), cut(1), grep(1), paste(1), sed(1), regcmp(3C), attributes(5)
SunOS 5.9 12 Jul 1999 regex(1F)