regex(1F) MISC. REFERENCE MANUAL PAGES 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 tem-
plate 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 $m9 at parse time. This feature gives
regex much of the power of cut(1), paste(1), and grep(1),
and some of the capabilities of sed(1). If there is no tem-
plate, the default is "$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 con-
tains one of the numbers 1, 2, 3, 4, 5 to the letters a, b,
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regex(1F) MISC. REFERENCE MANUAL PAGES regex(1F)
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".
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.
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 under-
scores () or slashes (/), but [/a-zA-Z] will.
The regular expressions accepted by regcmp differ slightly
from other utilities (i.e., sed, grep, awk, ed, etc.).
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.
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regex(1F) MISC. REFERENCE MANUAL PAGES regex(1F)
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/System Administrator's Reference Manual.
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