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Annotated edit history of glob(7) version 1, including all changes. View license author blame.
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1 perry 1 GLOB
2 !!!GLOB
3 NAME
4 DESCRIPTION
5 WILDCARD MATCHING
6 PATHNAMES
7 EMPTY LISTS
8 NOTES
9 SEE ALSO
10 ----
11 !!NAME
12
13
14 glob - Globbing pathnames
15 !!DESCRIPTION
16
17
18 Long ago, in Unix V6, there was a program ''/etc/glob''
19 that would expand wildcard patterns. Soon afterwards this
20 became a shell built-in.
21
22
23 These days there is also a library routine glob(3)
24 that will perform this function for a user
25 program.
26
27
28 The rules are as follows (POSIX 1003.2, 3.13).
29 !!WILDCARD MATCHING
30
31
32 A string is a wildcard pattern if it contains one of the
33 characters `?', `*' or `[['. Globbing is the operation that
34 expands a wildcard pattern into the list of pathnames
35 matching the pattern. Matching is defined by:
36
37
38 A `?' (not between brackets) matches any single
39 character.
40
41
42 A `*' (not between brackets) matches any string, including
43 the empty string.
44
45
46 __Character classes__
47
48
49 An expression `[[...]' where the first character after the
50 leading `[[' is not an `!' matches a single character, namely
51 any of the characters enclosed by the brackets. The string
52 enclosed by the brackets cannot be empty; therefore `]' can
53 be allowed between the brackets, provided that it is the
54 first character. (Thus, `[[][[!]' matches the three characters
55 `[[', `]' and `!'.)
56
57
58 __Ranges__
59
60
61 There is one special convention: two characters separated by
62 `-' denote a range. (Thus, `[[A-Fa-f0-9]' is equivalent to
63 `[[ABCDEFabcdef0123456789]'.) One may include `-' in its
64 literal meaning by making it the first or last character
65 between the brackets. (Thus, `[[]-]' matches just the two
66 characters `]' and `-', and `[[--/]' matches the three
67 characters `-', `.', `/'.)
68
69
70 __Complementation__
71
72
73 An expression `[[!...]' matches a single character, namely
74 any character that is not matched by the expression obtained
75 by removing the first `!' from it. (Thus, `[[!]a-]' matches
76 any single character except `]', `a' and `-'.)
77
78
79 One can remove the special meaning of `?', `*' and `[[' by
80 preceding them by a backslash, or, in case this is part of a
81 shell command line, enclosing them in quotes. Between
82 brackets these characters stand for themselves. Thus,
83 `[[[[?*]' matches the four characters `[[', `?', `*' and
84 `'.
85 !!PATHNAMES
86
87
88 Globbing is applied on each of the components of a pathname
89 separately. A `/' in a pathname cannot be matched by a `?'
90 or `*' wildcard, or by a range like `[[.-0]'. A range cannot
91 contain an explicit `/' character; this would lead to a
92 syntax error.
93
94
95 If a filename starts with a `.', this character must be
96 matched explicitly. (Thus, `rm *' will not remove .profile,
97 and `tar c *' will not archive all your files; `tar c .' is
98 better.)
99 !!EMPTY LISTS
100
101
102 The nice and simple rule given above: `expand a wildcard
103 pattern into the list of matching pathnames' was the
104 original Unix definition. It allowed one to have patterns
105 that expand into an empty list, as in
106
107
108 xv -wait 0 *.gif *.jpg
109 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 behaviour by setting ''allow_null_glob_expansion=true''.
110
111
112 (Similar problems occur elsewhere. E.g., where old scripts
113 have
114
115
116 rm `find . -name
117 new scripts require
118
119
120 rm -f nosuchfile `find . -name
121 to avoid error messages from ''rm'' called with an empty argument list.)
122 !!NOTES
123
124
125 __Regular expressions__
126
127
128 Note that wildcard patterns are not regular expressions,
129 although they are a bit similar. First of all, they match
130 filenames, rather than text, and secondly, the conventions
131 are not the same: e.g., in a regular expression `*' means
132 zero or more copies of the preceding thing.
133
134
135 Now that regular expressions have bracket expressions where
136 the negation is indicated by a `^', POSIX has declared the
137 effect of a wildcard pattern `[[^...]' to be
138 undefined.
139
140
141 __Character classes and
142 Internationalization__
143
144
145 Of course ranges were originally meant to be ASCII ranges,
146 so that `[[ -%]' stands for `[[ !
147
148
149 (iii) Ranges X-Y comprise all characters that fall between X
150 and Y (inclusive) in the currect collating sequence as
151 defined by the LC_COLLATE category in the current
152 locale.
153
154
155 (iv) Named character classes, like
156
157
158 [[:alnum:] [[:alpha:] [[:blank:] [[:cntrl:]
159 [[:digit:] [[:graph:] [[:lower:] [[:print:]
160 [[:punct:] [[:space:] [[:upper:] [[:xdigit:]
161 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 alphabet. These character classes are defined by the LC_CTYPE category in the current locale.
162
163
164 (v) Collating symbols, like `[[.ch.]' or `[[.a-acute.]', where
165 the string between `[[.' and `.]' is a collating element
166 defined for the current locale. Note that this may be a
167 multi-character element.
168
169
170 (vi) Equivalence class expressions, like `[[=a=]', where the
171 string between `[[=' and `=]' is any collating element from
172 its equivalence class, as defined for the current locale.
173 For example, `[[[[=a=]]' might be equivalent to
174 `[[a
175 !!SEE ALSO
176
177
178 sh(1), glob(3), fnmatch(3),
179 locale(7), regex(7)
180 ----
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