awk and POSIX character class Post: 302459419

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Top Forums Shell Programming and Scripting awk and POSIX character class Post 302459419 by alister on Monday 4th of October 2010 03:38:20 PM

10-04-2010

Registered User

Quote:

Originally Posted by anthalamus

thanks guys,
here's the revised version:

Code:

echo "./comparecdna.summary" | awk '/^[.][/]compare[[:alnum:]]+[.]summary$/' # returns: ./comparecdna.summary
echo "./compare_cdna.summary" | awk '/^[.][/]compare_[[:alnum:]]+[.]summary$/' # returns: ./compare_cdna.summary
echo "./compare_cdna_peptide.summary" | awk '/^[.][/]compare_[_[:alnum:]]+[.]summary$/' # returns: ./compare_cdna_peptide.summary
[:word:] is non-standard POSIX apparently

alister, the "/" seems not need be escaped here, maybe because it's by itself within the []?

It is required according to the posix standard. I strongly suggest that you do not depend on your implementation's behavior. Perhaps your awk allows that, but when run on a different implementation it may choke thusly:

Code:

$ echo "./comparecdna.summary" | awk '/^[.][/]compare[[:alnum:]]+[.]summary$/'
awk: nonterminated character class ^[.][
 source line number 1
 context is
         >>> /^[.][/ <<<

AWK thinks it's an unterminated class because the regular expression delimiter is encountered.

For more info, read the "Regular Expressions" section @ awk

Regards,
Alister

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iswgraph

ISWGRAPH(3)						     Linux Programmer's Manual						       ISWGRAPH(3)

NAME

       iswgraph - test for graphic wide character

SYNOPSIS

       #include <wctype.h>

       int iswgraph(wint_t wc);

DESCRIPTION

       The  iswgraph() function is the wide-character equivalent of the isgraph(3) function.  It tests whether wc is a wide character belonging to
       the wide-character class "graph".

       The wide-character class "graph" is a subclass of the wide-character class "print".

       Being a subclass of the wide-character class "print", the wide-character class "graph" is disjoint from the wide-character class "cntrl".

       The wide-character class "graph" is disjoint from the wide-character class "space" and therefore also disjoint from its subclass "blank".

       The wide-character class "graph" contains all the wide characters from the wide-character class "print" except  the  space  character.	It
       therefore contains the wide-character classes "alnum" and "punct".

RETURN VALUE

       The  iswgraph()	function  returns  nonzero if wc is a wide character belonging to the wide-character class "graph".  Otherwise, it returns
       zero.

ATTRIBUTES

       For an explanation of the terms used in this section, see attributes(7).

       +-----------+---------------+----------------+
       |Interface  | Attribute	   | Value	    |
       +-----------+---------------+----------------+
       |iswgraph() | Thread safety | MT-Safe locale |
       +-----------+---------------+----------------+
CONFORMING TO

       POSIX.1-2001, POSIX.1-2008, C99.

NOTES

       The behavior of iswgraph() depends on the LC_CTYPE category of the current locale.

SEE ALSO

       isgraph(3), iswctype(3)

COLOPHON

       This page is part of release 4.15 of the Linux man-pages project.  A description of the project, information about reporting bugs, and  the
       latest version of this page, can be found at https://www.kernel.org/doc/man-pages/.

GNU
								    2015-08-08							       ISWGRAPH(3)