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Top Forums Shell Programming and Scripting Regex issue with \s in character class. Post 303042631 by blackrageous on Wednesday 1st of January 2020 10:12:33 PM
Old 01-02-2020
Regex issue with \s in character class.

Anybody have an explanation for why \s doesn't match ' ' in a character class? Here are 3 examples with the final example showing that \s in a character class (demonstrated by using egrep -o) fails:

\s works outside of class..

Code:
# echo " FOO " | egrep -o '\s[A-Z]+\s'
 FOO

Here is a sanity check using ' '...

Code:
# echo " FOO " | egrep -o '[  ][A-Z]+[  ]'
 FOO

Here I try with \s in a character class
Code:
# echo " FOO " | egrep -o '[\s][A-Z]+[\s]'
#

 

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Symbol(3pm)						 Perl Programmers Reference Guide					       Symbol(3pm)

NAME
Symbol - manipulate Perl symbols and their names SYNOPSIS
use Symbol; $sym = gensym; open($sym, "filename"); $_ = <$sym>; # etc. ungensym $sym; # no effect # replace *FOO{IO} handle but not $FOO, %FOO, etc. *FOO = geniosym; print qualify("x"), " "; # "Test::x" print qualify("x", "FOO"), " " # "FOO::x" print qualify("BAR::x"), " "; # "BAR::x" print qualify("BAR::x", "FOO"), " "; # "BAR::x" print qualify("STDOUT", "FOO"), " "; # "main::STDOUT" (global) print qualify(*x), " "; # returns *x print qualify(*x, "FOO"), " "; # returns *x use strict refs; print { qualify_to_ref $fh } "foo! "; $ref = qualify_to_ref $name, $pkg; use Symbol qw(delete_package); delete_package('Foo::Bar'); print "deleted " unless exists $Foo::{'Bar::'}; DESCRIPTION
"Symbol::gensym" creates an anonymous glob and returns a reference to it. Such a glob reference can be used as a file or directory handle. For backward compatibility with older implementations that didn't support anonymous globs, "Symbol::ungensym" is also provided. But it doesn't do anything. "Symbol::geniosym" creates an anonymous IO handle. This can be assigned into an existing glob without affecting the non-IO portions of the glob. "Symbol::qualify" turns unqualified symbol names into qualified variable names (e.g. "myvar" -> "MyPackage::myvar"). If it is given a sec- ond parameter, "qualify" uses it as the default package; otherwise, it uses the package of its caller. Regardless, global variable names (e.g. "STDOUT", "ENV", "SIG") are always qualified with "main::". Qualification applies only to symbol names (strings). References are left unchanged under the assumption that they are glob references, which are qualified by their nature. "Symbol::qualify_to_ref" is just like "Symbol::qualify" except that it returns a glob ref rather than a symbol name, so you can use the result even if "use strict 'refs'" is in effect. "Symbol::delete_package" wipes out a whole package namespace. Note this routine is not exported by default--you may want to import it explicitly. perl v5.8.0 2002-06-01 Symbol(3pm)
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