03-04-2008
Extract a substring using regular expression
Hello:
I'm trying to extracta a matching substring from a string using regular expression. I need to extract the date part of any giving string.
All input string will have date in YYYYMMDD format in them, but it can be anywhere in the string.
Eg.
The_Mummy20080125_New
Lost_20071227_In_time
Last20010915Samurai
All I want is to assign the 8 digit date part to a variable.
I tried
$Date_val = echo "The_Mummy20080125_New" | sed "s/._\([[:digit:]]\{8\}\)$/\1/p"
But it does not work. Someone please help me.
Thanks,
Raja
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textutil::trim(n) Text and string utilities, macro processing textutil::trim(n)
__________________________________________________________________________________________________________________________________________________
NAME
textutil::trim - Procedures to trim strings
SYNOPSIS
package require Tcl 8.2
package require textutil::trim ?0.7?
::textutil::trim::trim string ?regexp?
::textutil::trim::trimleft string ?regexp?
::textutil::trim::trimright string ?regexp?
::textutil::trim::trimPrefix string prefix
::textutil::trim::trimEmptyHeading string
_________________________________________________________________
DESCRIPTION
The package textutil::trim provides commands that trim strings using arbitrary regular expressions.
The complete set of procedures is described below.
::textutil::trim::trim string ?regexp?
Remove in string any leading and trailing substring according to the regular expression regexp and return the result as a new
string. This is done for all lines in the string, that is any substring between 2 newline chars, or between the beginning of the
string and a newline, or between a newline and the end of the string, or, if the string contain no newline, between the beginning
and the end of the string. The regular expression regexp defaults to "[ \t]+".
::textutil::trim::trimleft string ?regexp?
Remove in string any leading substring according to the regular expression regexp and return the result as a new string. This apply
on any line in the string, that is any substring between 2 newline chars, or between the beginning of the string and a newline, or
between a newline and the end of the string, or, if the string contain no newline, between the beginning and the end of the string.
The regular expression regexp defaults to "[ \t]+".
::textutil::trim::trimright string ?regexp?
Remove in string any trailing substring according to the regular expression regexp and return the result as a new string. This apply
on any line in the string, that is any substring between 2 newline chars, or between the beginning of the string and a newline, or
between a newline and the end of the string, or, if the string contain no newline, between the beginning and the end of the string.
The regular expression regexp defaults to "[ \t]+".
::textutil::trim::trimPrefix string prefix
Removes the prefix from the beginning of string and returns the result. The string is left unchanged if it doesn't have prefix at
its beginning.
::textutil::trim::trimEmptyHeading string
Looks for empty lines (including lines consisting of only whitespace) at the beginning of the string and removes it. The modified
string is returned as the result of the command.
BUGS, IDEAS, FEEDBACK
This document, and the package it describes, will undoubtedly contain bugs and other problems. Please report such in the category textutil
of the Tcllib SF Trackers [http://sourceforge.net/tracker/?group_id=12883]. Please also report any ideas for enhancements you may have for
either package and/or documentation.
SEE ALSO
regexp(n), split(n), string(n)
KEYWORDS
prefix, regular expression, string, trimming
CATEGORY
Text processing
textutil 0.7 textutil::trim(n)