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)

PROLOG         top

       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.

NAME         top

       basename — return non-directory portion of a pathname

SYNOPSIS         top

       basename string [suffix]

DESCRIPTION         top

       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.

OPTIONS         top

       None.

OPERANDS         top

       The following operands shall be supported:

       string    A string.

       suffix    A string.

STDIN         top

       Not used.

INPUT FILES         top

       None.

ENVIRONMENT VARIABLES         top

       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.

ASYNCHRONOUS EVENTS         top

       Default.

STDOUT         top

       The basename utility shall write a line to the standard output in the
       following format:

           "%s\n", <resulting string>

STDERR         top

       The standard error shall be used only for diagnostic messages.

OUTPUT FILES         top

       None.

EXTENDED DESCRIPTION         top

       None.

EXIT STATUS         top

       The following exit values shall be returned:

        0    Successful completion.

       >0    An error occurred.

CONSEQUENCES OF ERRORS         top

       Default.

       The following sections are informative.

APPLICATION USAGE         top

       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.

EXAMPLES         top

       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)"

RATIONALE         top

       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.

FUTURE DIRECTIONS         top

       None.

SEE ALSO         top

       Section 2.5, Parameters and Variables, dirname(1p)

       The Base Definitions volume of POSIX.1‐2008, Section 3.267, Pathname,
       Chapter 8, Environment Variables

COPYRIGHT         top

       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)