1BASENAME(P) POSIX Programmer's Manual BASENAME(P)
2
6 basename - return non-directory portion of a pathname
7
9 basename string [suffix]
10
12 The string operand shall be treated as a pathname, as defined in the
13 Base Definitions volume of IEEE Std 1003.1-2001, Section 3.266, Path‐
14 name. The string string shall be converted to the filename correspond‐
15 ing to the last pathname component in string and then the suffix string
16 suffix, if present, shall be removed. This shall be done by performing
17 actions equivalent to the following steps in order:
18 1. If string is a null string, it is unspecified whether the resulting
20 string is '.' or a null string. In either case, skip steps 2
21 through 6.
22 2. If string is "//" , it is implementation-defined whether steps 3 to
24 6 are skipped or processed.
25 3. If string consists entirely of slash characters, string shall be
27 set to a single slash character. In this case, skip steps 4 to 6.
28 4. If there are any trailing slash characters in string, they shall be
30 removed.
31 5. If there are any slash characters remaining in string, the prefix
33 of string up to and including the last slash character in string
34 shall be removed.
35 6. If the suffix operand is present, is not identical to the charac‐
37 ters remaining in string, and is identical to a suffix of the char‐
38 acters remaining in string, the suffix suffix shall be removed from
39 string. Otherwise, string is not modified by this step. It shall
40 not be considered an error if suffix is not found in string.
41 The resulting string shall be written to standard output.
43
45 None.
46
48 The following operands shall be supported:
49 string A string.
51 suffix A string.
53
56 Not used.
57
59 None.
60
62 The following environment variables shall affect the execution of base‐
63 name:
64 LANG Provide a default value for the internationalization variables
66 that are unset or null. (See the Base Definitions volume of
67 IEEE Std 1003.1-2001, Section 8.2, Internationalization Vari‐
68 ables for the precedence of internationalization variables used
69 to determine the values of locale categories.)
70 LC_ALL If set to a non-empty string value, override the values of all
72 the other internationalization variables.
73 LC_CTYPE
75 Determine the locale for the interpretation of sequences of
76 bytes of text data as characters (for example, single-byte as
77 opposed to multi-byte characters in arguments).
78 LC_MESSAGES
80 Determine the locale that should be used to affect the format
81 and contents of diagnostic messages written to standard error.
82 NLSPATH
84 Determine the location of message catalogs for the processing of
85 LC_MESSAGES .
86
89 Default.
90
92 The basename utility shall write a line to the standard output in the
93 following format:
94 "%s\n", <resulting string>
97
99 The standard error shall be used only for diagnostic messages.
100
102 None.
103
105 None.
106
108 The following exit values shall be returned:
109 0 Successful completion.
111 >0 An error occurred.
113
116 Default.
117 The following sections are informative.
119
121 The definition of pathname specifies implementation-defined behavior
122 for pathnames starting with two slash characters. Therefore, applica‐
123 tions shall not arbitrarily add slashes to the beginning of a pathname
124 unless they can ensure that there are more or less than two or are pre‐
125 pared to deal with the implementation-defined consequences.
126
128 If the string string is a valid pathname:
129 $(basename "string")
132 produces a filename that could be used to open the file named by string
134 in the directory returned by:
135 $(dirname "string")
138 If the string string is not a valid pathname, the same algorithm is
140 used, but the result need not be a valid filename. The basename util‐
141 ity is not expected to make any judgements about the validity of string
142 as a pathname; it just follows the specified algorithm to produce a
143 result string.
144 The following shell script compiles /usr/src/cmd/cat.c and moves the
146 output to a file named cat in the current directory when invoked with
147 the argument /usr/src/cmd/cat or with the argument /usr/src/cmd/cat.c:
148 c99 $(dirname "$1")/$(basename "$1" .c).c
151 mv a.out $(basename "$1" .c)
152
154 The behaviors of basename and dirname have been coordinated so that
155 when string is a valid pathname:
156 $(basename "string")
159 would be a valid filename for the file in the directory:
161 $(dirname "string")
164 This would not work for the early proposal versions of these utilities
166 due to the way it specified handling of trailing slashes.
167 Since the definition of pathname specifies implementation-defined
169 behavior for pathnames starting with two slash characters, this volume
170 of IEEE Std 1003.1-2001 specifies similar implementation-defined behav‐
171 ior for the basename and dirname utilities.
172
174 None.
175
177 Parameters and Variables , dirname()
178
180 Portions of this text are reprinted and reproduced in electronic form
181 from IEEE Std 1003.1, 2003 Edition, Standard for Information Technology
182 -- Portable Operating System Interface (POSIX), The Open Group Base
183 Specifications Issue 6, Copyright (C) 2001-2003 by the Institute of
184 Electrical and Electronics Engineers, Inc and The Open Group. In the
185 event of any discrepancy between this version and the original IEEE and
186 The Open Group Standard, the original IEEE and The Open Group Standard
187 is the referee document. The original Standard can be obtained online
188 at http://www.opengroup.org/unix/online.html .
189IEEE/The Open Group 2003 BASENAME(P)