12-01-2015
Quote:
Originally Posted by
RudiC
Please be aware that 2^5 = 32, not 25 (= 5^2).
If your input has all bits of interest set, and the all zero variant is to be excluded, you'll have 2^n - 2 patterns to work on.
I guess my question at this point is whether or not the above code is giving my all of the combinations I am looking for. For the examples I tested, the output looks correct, meaning that I can't come up with any combinations that are missing. It also appears that I counted the output incorrectly. There are 30 subsets printed by Don Cragun's code, which matches your expected number.
My most complicated patter has 11 on bits, which corresponds to 2046 subsets according to your algorithm. Each of these will be checked against a check list of ~2000 patterns. This will likely not be lightning fast using the script above, but do you see any potential issues with memory?
LMHmedchem
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LEARN ABOUT DEBIAN
shellexp
SHELLEXP(3) Library Functions Manual SHELLEXP(3)
NAME
shellexp - match string against a cruft filter pattern
SYNOPSIS
extern int shellexp(const char *string, const char *pattern);
DESCRIPTION
The shellexp() function is similar to fnmatch(3), but works with cruft patterns instead of standard glob(7) patterns. The function returns
a true value if string matches the cruft pattern pattern, and a false value (0) otherwise. Returns -1 in case of pattern syntax error.
Cruft patterns are similar to glob(7) patterns, but are not fully compatible. The following special characters are supported:
? (a question mark)
matches exacly one character of string other than a slash.
* matches zero or more characters of string other than a slash.
/** or /**/
matches zero or more path components in string. Please note that you can only use ** when directly following a slash, and further-
more, only when either directly preceding a slash or at the very end of pattern. A ** followed by anything other than a slash makes
pattern invalid. A ** following anything else than a slash reduces it to having the same effect as *.
[character-class]
Matches any character between the brackets exactly once. Named character classes are NOT supported. If the first character of the
class is ! or ^, then the meaning is inverted (matches any character NOT listed between the brackets). If you want to specify a
literal closing bracket in the class, then specify it as the first (or second, if you want to negate) character after the opening
bracket. Also, simple ASCII-order ranges are supported using a dash character (see examples section).
Any other character matches itself.
EXAMPLES
/a/b*/*c
matches /a/b/xyz.c, as well as /a/bcd/.c, but not /a/b/c/d.c.
/a/**/*.c
matches all of the following: /a/a.c, /a/b/a.c, /a/b/c/a.c and /a/b/c/d/a.c.
/a/[0-9][^0-9]*
matches /a/1abc, but not /a/12bc.
BUGS
Uses constant-length 1000 byte buffers to hold filenames. Also uses recursive function calls, which are not very efficient. Does not vali-
date the pattern before matching, so any pattern errors (unbalanced brackets or misplaced **) are only reported when and if the matching
algorithm reaches them.
SEE ALSO
fnmatch(3), glob(3), cruft(8) and dash-search(1).
AUTHOR
This manual page was written by Marcin Owsiany <porridge@debian.org>, for the Debian GNU/Linux system (but may be used by others).
October 17, 2007 SHELLEXP(3)