1BASENAME(1P) POSIX Programmer's Manual BASENAME(1P)
2
6 This manual page is part of the POSIX Programmer's Manual. The Linux
7 implementation of this interface may differ (consult the corresponding
8 Linux manual page for details of Linux behavior), or the interface may
9 not be implemented on Linux.
10
12 basename - return non-directory portion of a pathname
13
15 basename string [suffix]
16
18 The string operand shall be treated as a pathname, as defined in the
19 Base Definitions volume of IEEE Std 1003.1-2001, Section 3.266, Path‐
20 name. The string string shall be converted to the filename correspond‐
21 ing to the last pathname component in string and then the suffix string
22 suffix, if present, shall be removed. This shall be done by performing
23 actions equivalent to the following steps in order:
24 1. If string is a null string, it is unspecified whether the resulting
26 string is '.' or a null string. In either case, skip steps 2
27 through 6.
28 2. If string is "//", it is implementation-defined whether steps 3 to
30 6 are skipped or processed.
31 3. If string consists entirely of slash characters, string shall be
33 set to a single slash character. In this case, skip steps 4 to 6.
34 4. If there are any trailing slash characters in string, they shall be
36 removed.
37 5. If there are any slash characters remaining in string, the prefix
39 of string up to and including the last slash character in string
40 shall be removed.
41 6. If the suffix operand is present, is not identical to the charac‐
43 ters remaining in string, and is identical to a suffix of the char‐
44 acters remaining in string, the suffix suffix shall be removed from
45 string. Otherwise, string is not modified by this step. It shall
46 not be considered an error if suffix is not found in string.
47 The resulting string shall be written to standard output.
49
51 None.
52
54 The following operands shall be supported:
55 string A string.
57 suffix A string.
59
62 Not used.
63
65 None.
66
68 The following environment variables shall affect the execution of base‐
69 name:
70 LANG Provide a default value for the internationalization variables
72 that are unset or null. (See the Base Definitions volume of
73 IEEE Std 1003.1-2001, Section 8.2, Internationalization Vari‐
74 ables for the precedence of internationalization variables used
75 to determine the values of locale categories.)
76 LC_ALL If set to a non-empty string value, override the values of all
78 the other internationalization variables.
79 LC_CTYPE
81 Determine the locale for the interpretation of sequences of
82 bytes of text data as characters (for example, single-byte as
83 opposed to multi-byte characters in arguments).
84 LC_MESSAGES
86 Determine the locale that should be used to affect the format
87 and contents of diagnostic messages written to standard error.
88 NLSPATH
90 Determine the location of message catalogs for the processing of
91 LC_MESSAGES .
92
95 Default.
96
98 The basename utility shall write a line to the standard output in the
99 following format:
100 "%s\n", <resulting string>
103
105 The standard error shall be used only for diagnostic messages.
106
108 None.
109
111 None.
112
114 The following exit values shall be returned:
115 0 Successful completion.
117 >0 An error occurred.
119
122 Default.
123 The following sections are informative.
125
127 The definition of pathname specifies implementation-defined behavior
128 for pathnames starting with two slash characters. Therefore, applica‐
129 tions shall not arbitrarily add slashes to the beginning of a pathname
130 unless they can ensure that there are more or less than two or are pre‐
131 pared to deal with the implementation-defined consequences.
132
134 If the string string is a valid pathname:
135 $(basename "string")
138 produces a filename that could be used to open the file named by string
140 in the directory returned by:
141 $(dirname "string")
144 If the string string is not a valid pathname, the same algorithm is
146 used, but the result need not be a valid filename. The basename util‐
147 ity is not expected to make any judgements about the validity of string
148 as a pathname; it just follows the specified algorithm to produce a
149 result string.
150 The following shell script compiles /usr/src/cmd/cat.c and moves the
152 output to a file named cat in the current directory when invoked with
153 the argument /usr/src/cmd/cat or with the argument /usr/src/cmd/cat.c:
154 c99 $(dirname "$1")/$(basename "$1" .c).c
157 mv a.out $(basename "$1" .c)
158
160 The behaviors of basename and dirname have been coordinated so that
161 when string is a valid pathname:
162 $(basename "string")
165 would be a valid filename for the file in the directory:
167 $(dirname "string")
170 This would not work for the early proposal versions of these utilities
172 due to the way it specified handling of trailing slashes.
173 Since the definition of pathname specifies implementation-defined
175 behavior for pathnames starting with two slash characters, this volume
176 of IEEE Std 1003.1-2001 specifies similar implementation-defined behav‐
177 ior for the basename and dirname utilities.
178
180 None.
181
183 Parameters and Variables, dirname()
184
186 Portions of this text are reprinted and reproduced in electronic form
187 from IEEE Std 1003.1, 2003 Edition, Standard for Information Technology
188 -- Portable Operating System Interface (POSIX), The Open Group Base
189 Specifications Issue 6, Copyright (C) 2001-2003 by the Institute of
190 Electrical and Electronics Engineers, Inc and The Open Group. In the
191 event of any discrepancy between this version and the original IEEE and
192 The Open Group Standard, the original IEEE and The Open Group Standard
193 is the referee document. The original Standard can be obtained online
194 at http://www.opengroup.org/unix/online.html .
195IEEE/The Open Group 2003 BASENAME(1P)