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PROLOG | NAME | SYNOPSIS | DESCRIPTION | OPTIONS | OPERANDS | STDIN | INPUT FILES | ENVIRONMENT VARIABLES | ASYNCHRONOUS EVENTS | STDOUT | STDERR | OUTPUT FILES | EXTENDED DESCRIPTION | EXIT STATUS | CONSEQUENCES OF ERRORS | APPLICATION USAGE | EXAMPLES | RATIONALE | FUTURE DIRECTIONS | SEE ALSO | COPYRIGHT |
BASENAME(1P) POSIX Programmer's Manual BASENAME(1P)
This manual page is part of the POSIX Programmer's Manual. The Linux
implementation of this interface may differ (consult the
corresponding Linux manual page for details of Linux behavior), or
the interface may not be implemented on Linux.
basename — return non-directory portion of a pathname
basename string [suffix]
The string operand shall be treated as a pathname, as defined in the
Base Definitions volume of POSIX.1‐2008, Section 3.267, Pathname.
The string string shall be converted to the filename corresponding 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 equivalent to the following steps in order:
1. 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.
2. If string is "//", it is implementation-defined whether steps 3
to 6 are skipped or processed.
3. If string consists entirely of <slash> characters, string shall
be set to a single <slash> character. In this case, skip steps 4
to 6.
4. If there are any trailing <slash> characters in string, they
shall be removed.
5. 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.
6. 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 suffix 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 output.
None.
The following operands shall be supported:
string A string.
suffix A string.
Not used.
None.
The following environment variables shall affect the execution of
basename:
LANG Provide a default value for the internationalization
variables that are unset or null. (See the Base Definitions
volume of POSIX.1‐2008, Section 8.2, Internationalization
Variables for the precedence of internationalization
variables used to determine the values of locale
categories.)
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 messages written to
standard error.
NLSPATH Determine the location of message catalogs for the
processing of LC_MESSAGES.
Default.
The basename utility shall write a line to the standard output in the
following format:
"%s\n", <resulting string>
The standard error shall be used only for diagnostic messages.
None.
None.
The following exit values shall be returned:
0 Successful completion.
>0 An error occurred.
Default.
The following sections are informative.
The definition of pathname specifies implementation-defined behavior
for pathnames starting with two <slash> characters. Therefore,
applications shall not arbitrarily add <slash> characters 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.
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:
$(dirname -- "string")
If the string string is not a valid pathname, the same algorithm is
used, but the result need not be a valid filename. The basename
utility is not expected to make any judgements about the validity of
string as a pathname; it just follows the specified algorithm to
produce a result string.
The following shell script compiles /usr/src/cmd/cat.c and moves the
output to a file named cat in the current directory when invoked with
the argument /usr/src/cmd/cat or with the argument
/usr/src/cmd/cat.c:
c99 -- "$(dirname -- "$1")/$(basename -- "$1" .c).c" &&
mv a.out "$(basename -- "$1" .c)"
The behaviors of basename and dirname have been coordinated 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 <slash>
characters.
Since the definition of pathname specifies implementation-defined
behavior for pathnames starting with two <slash> characters, this
volume of POSIX.1‐2008 specifies similar implementation-defined
behavior for the basename and dirname utilities.
None.
Section 2.5, Parameters and Variables, dirname(1p)
The Base Definitions volume of POSIX.1‐2008, Section 3.267, Pathname,
Chapter 8, Environment Variables
Portions of this text are reprinted and reproduced in electronic form
from IEEE Std 1003.1, 2013 Edition, Standard for Information
Technology -- Portable Operating System Interface (POSIX), The Open
Group Base Specifications Issue 7, Copyright (C) 2013 by the
Institute of Electrical and Electronics Engineers, Inc and The Open
Group. (This is POSIX.1-2008 with the 2013 Technical Corrigendum 1
applied.) 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.unix.org/online.html .
Any typographical or formatting errors that appear in this page are
most likely to have been introduced during the conversion of the
source files to man page format. To report such errors, see
https://www.kernel.org/doc/man-pages/reporting_bugs.html .
IEEE/The Open Group 2013 BASENAME(1P)
Pages that refer to this page: dirname(1p), basename(3p)