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GLOB(7)			   Linux Programmer's Manual		       GLOB(7)

NAME
       glob - globbing pathnames

DESCRIPTION
       Long  ago,  in UNIX V6, there was a program /etc/glob that would	expand
       wildcard	patterns.  Soon	afterward this became a	shell built-in.

       These days there	is also	a library routine glob(3)  that	 will  perform
       this function for a user	program.

       The rules are as	follows	(POSIX.2, 3.13).

   Wildcard matching
       A  string  is  a	 wildcard pattern if it	contains one of	the characters
       '?', '*'	or '['.	 Globbing is the operation  that  expands  a  wildcard
       pattern	into  the list of pathnames matching the pattern.  Matching is
       defined by:

       A '?' (not between brackets) matches any	single character.

       A '*' (not between brackets) matches any	string,	 including  the	 empty
       string.

       Character classes

       An  expression  "[...]" where the first character after the leading '['
       is not an '!' matches a single character, namely	any of the  characters
       enclosed	 by  the brackets.  The	string enclosed	by the brackets	cannot
       be empty; therefore ']' can be allowed between the  brackets,  provided
       that it is the first character.	(Thus, "[][!]" matches the three char-
       acters '[', ']' and '!'.)

       Ranges

       There is	one special convention:	two characters separated by '-'	denote
       a    range.    (Thus,   "[A-Fa-f0-9]"   is   equivalent	 to   "[ABCDE-
       Fabcdef0123456789]".)  One may include '-' in its  literal  meaning  by
       making  it  the	first  or last character between the brackets.	(Thus,
       "[]-]" matches just the two characters ']' and '-', and "[--0]" matches
       the three characters '-', '.', '0', since '/' cannot be matched.)

       Complementation

       An expression "[!...]" matches a	single character, namely any character
       that is not matched by the expression obtained by  removing  the	 first
       '!'  from it.  (Thus, "[!]a-]" matches any single character except ']',
       'a' and '-'.)

       One can remove the special meaning of '?', '*'  and  '['	 by  preceding
       them  by	a backslash, or, in case this is part of a shell command line,
       enclosing them in quotes.  Between brackets these characters stand  for
       themselves.   Thus,  "[[?*\]" matches the four characters '[', '?', '*'
       and '\'.

   Pathnames
       Globbing	is applied on each of the components of	a pathname separately.
       A '/' in	a pathname cannot be matched by	a '?' or '*' wildcard, or by a
       range like "[.-0]".  A range cannot contain an explicit '/'  character;
       this would lead to a syntax error.

       If a filename starts with a '.',	this character must be matched explic-
       itly.  (Thus, rm	* will not remove .profile, and	tar c *	will  not  ar-
       chive all your files; tar c . is	better.)

   Empty lists
       The  nice  and simple rule given	above: "expand a wildcard pattern into
       the list	of matching pathnames" was the original	UNIX  definition.   It
       allowed one to have patterns that expand	into an	empty list, as in

	   xv -wait 0 *.gif *.jpg

       where  perhaps  no  *.gif files are present (and	this is	not an error).
       However,	POSIX requires that a wildcard pattern is left unchanged  when
       it  is  syntactically  incorrect,  or the list of matching pathnames is
       empty.  With bash one can force the classical behavior using this  com-
       mand:

	   shopt -s nullglob

       (Similar	problems occur elsewhere.  For example,	where old scripts have

	   rm `find . -name "*~"`

       new scripts require

	   rm -f nosuchfile `find . -name "*~"`

       to avoid	error messages from rm called with an empty argument list.)

NOTES
   Regular expressions
       Note  that wildcard patterns are	not regular expressions, although they
       are a bit similar.  First of all, they  match  filenames,  rather  than
       text, and secondly, the conventions are not the same: for example, in a
       regular expression '*' means zero  or  more  copies  of	the  preceding
       thing.

       Now  that  regular expressions have bracket expressions where the nega-
       tion is indicated by a '^', POSIX has declared the effect of a wildcard
       pattern "[^...]"	to be undefined.

   Character classes and internationalization
       Of  course  ranges  were	 originally  meant to be ASCII ranges, so that
       "[ -%]" stands for "[ !"#$%]" and "[a-z]"  stands  for  "any  lowercase
       letter".	  Some	UNIX  implementations generalized this so that a range
       X-Y stands for the set of characters with code between the codes	for  X
       and  for	Y.  However, this requires the user to know the	character cod-
       ing in use on the local system, and moreover, is	not convenient if  the
       collating  sequence for the local alphabet differs from the ordering of
       the character codes.  Therefore,	POSIX extended	the  bracket  notation
       greatly,	 both  for  wildcard patterns and for regular expressions.  In
       the above we saw	three types of items that can occur in a  bracket  ex-
       pression: namely	(i) the	negation, (ii) explicit	single characters, and
       (iii) ranges.  POSIX specifies ranges in	an internationally more	useful
       way and adds three more types:

       (iii) Ranges X-Y	comprise all characters	that fall between X and	Y (in-
       clusive)	in the current collating sequence as defined by	the LC_COLLATE
       category	in the current locale.

       (iv) Named character classes, like

       [:alnum:]  [:alpha:]  [:blank:]	[:cntrl:]
       [:digit:]  [:graph:]  [:lower:]	[:print:]
       [:punct:]  [:space:]  [:upper:]	[:xdigit:]

       so  that	 one can say "[[:lower:]]" instead of "[a-z]", and have	things
       work in Denmark,	too, where there are three letters past	'z' in the al-
       phabet.	 These	character classes are defined by the LC_CTYPE category
       in the current locale.

       (v) Collating symbols, like "[.ch.]" or "[.a-acute.]", where the	string
       between	"[."  and  ".]"	is a collating element defined for the current
       locale.	Note that this may be a	multicharacter element.

       (vi) Equivalence	class expressions, like	"[=a=]", where the string  be-
       tween  "[="  and	 "=]"  is  any	collating element from its equivalence
       class, as defined for the current locale.  For example, "[[=a=]]" might
       be  equivalent  to "[a_a_a_a_a]", that is, to "[a[.a-acute.][.a-grave.][.a-
       umlaut.][.a-circumflex.]]".

SEE ALSO
       sh(1), fnmatch(3), glob(3), locale(7), regex(7)

COLOPHON
       This page is part of release 3.74 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
       http://www.kernel.org/doc/man-pages/.

Linux				  2012-07-28			       GLOB(7)

NAME | DESCRIPTION | NOTES | SEE ALSO | COLOPHON

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