1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
|
basename(P) basename(P)
NAME
basename - return non-directory portion of a pathname
SYNOPSIS
basename string [suffix]
DESCRIPTION
The string operand shall be treated as a pathname, as
defined in the Base Definitions volume of
IEEE Std 1003.1-2001, Section 3.266, Pathname. The
string string shall be converted to the filename corre-
sponding to the last pathname component in string and
then the suffix string suffix, if present, shall be
removed. This shall be done by performing actions equiv-
alent to the following steps in order:
If string is a null string, it is unspecified whether
the resulting string is '.' or a null string. In either
case, skip steps 2 through 6.
If string is "//" , it is implementation-defined whether
steps 3 to 6 are skipped or processed.
If string consists entirely of slash characters, string
shall be set to a single slash character. In this case,
skip steps 4 to 6.
If there are any trailing slash characters in string,
they shall be removed.
If there are any slash characters remaining in string,
the prefix of string up to and including the last slash
character in string shall be removed.
If the suffix operand is present, is not identical to
the characters remaining in string, and is identical to
a suffix of the characters remaining in string, the suf-
fix suffix shall be removed from string. Otherwise,
string is not modified by this step. It shall not be
considered an error if suffix is not found in string.
The resulting string shall be written to standard out-
put.
OPTIONS
None.
OPERANDS
The following operands shall be supported:
string A string.
suffix A string.
STDIN
Not used.
INPUT FILES
None.
ENVIRONMENT VARIABLES
The following environment variables shall affect the
execution of basename:
LANG Provide a default value for the internationaliza-
tion variables that are unset or null. (See the
Base Definitions volume of IEEE Std 1003.1-2001,
Section 8.2, Internationalization Variables for
the precedence of internationalization variables
used to determine the values of locale cate-
gories.)
LC_ALL If set to a non-empty string value, override the
values of all the other internationalization
variables.
LC_CTYPE
Determine the locale for the interpretation of
sequences of bytes of text data as characters
(for example, single-byte as opposed to multi-
byte characters in arguments).
LC_MESSAGES
Determine the locale that should be used to
affect the format and contents of diagnostic mes-
sages written to standard error.
NLSPATH
Determine the location of message catalogs for
the processing of LC_MESSAGES .
ASYNCHRONOUS EVENTS
Default.
STDOUT
The basename utility shall write a line to the standard
output in the following format:
"%s\n", <resulting string>
STDERR
The standard error shall be used only for diagnostic
messages.
OUTPUT FILES
None.
EXTENDED DESCRIPTION
None.
EXIT STATUS
The following exit values shall be returned:
0 Successful completion.
>0 An error occurred.
CONSEQUENCES OF ERRORS
Default.
The following sections are informative.
APPLICATION USAGE
The definition of pathname specifies implementation-
defined behavior for pathnames starting with two slash
characters. Therefore, applications shall not arbitrar-
ily add slashes to the beginning of a pathname unless
they can ensure that there are more or less than two or
are prepared to deal with the implementation-defined
consequences.
EXAMPLES
If the string string is a valid pathname:
$(basename "string")
produces a filename that could be used to open the file
named by string in the directory returned by:
$(dirname "string")
If the string string is not a valid pathname, the same
algorithm is used, but the result need not be a valid
filename. The basename utility is not expected to make
any judgements about the validity of string as a path-
name; it just follows the specified algorithm to produce
a result string.
The following shell script compiles /usr/src/cmd/cat.c
and moves the output to a file named cat in the current
directory when invoked with the argument
/usr/src/cmd/cat or with the argument
/usr/src/cmd/cat.c:
c99 $(dirname "$1")/$(basename "$1" .c).c
mv a.out $(basename "$1" .c)
RATIONALE
The behaviors of basename and dirname have been coordi-
nated so that when string is a valid pathname:
$(basename "string")
would be a valid filename for the file in the directory:
$(dirname "string")
This would not work for the early proposal versions of
these utilities due to the way it specified handling of
trailing slashes.
Since the definition of pathname specifies implementa-
tion-defined behavior for pathnames starting with two
slash characters, this volume of IEEE Std 1003.1-2001
specifies similar implementation-defined behavior for
the basename and dirname utilities.
FUTURE DIRECTIONS
None.
SEE ALSO
Parameters and Variables , dirname()
COPYRIGHT
Portions of this text are reprinted and reproduced in
electronic form from IEEE Std 1003.1, 2003 Edition,
Standard for Information Technology -- Portable Operat-
ing System Interface (POSIX), The Open Group Base Speci-
fications Issue 6, Copyright (C) 2001-2003 by the Insti-
tute of Electrical and Electronics Engineers, Inc and
The Open Group. In the event of any discrepancy between
this version and the original IEEE and The Open Group
Standard, the original IEEE and The Open Group Standard
is the referee document. The original Standard can be
obtained online at
http://www.opengroup.org/unix/online.html .
POSIX 2003 basename(P)
|
