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 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 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 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 tem-
plate, the default is $m0$m1$m2$m3$m4$m5$m6$m7$m8$m9.
OPTIONS
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 patterns.
EXAMPLES
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 con-
tains 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 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 match, regex returns FALSE, other-
wise TRUE.
NOTES
Patterns and templates must often be enclosed in single
quotes to turn off the special meanings of characters. Espe-
cially if you use the $m0 through $m9 variables in the tem-
plate, 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 under-
scores (_) 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.
ATTRIBUTES
See attributes(5) for descriptions of the following attri-
butes:
____________________________________________________________
| ATTRIBUTE TYPE | ATTRIBUTE VALUE |
|_____________________________|_____________________________|
| Availability | SUNWcsu |
|_____________________________|_____________________________|
SEE ALSO
awk(1), cut(1), grep(1), paste(1), sed(1), regcmp(3C),
attributes(5)
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