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BASENAME(1P)               POSIX Programmer's Manual              BASENAME(1P)
PROLOG
       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
       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 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  charac-
           ters remaining in string, and is identical to a suffix of the char-
           acters 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
       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 base-
       name:
       LANG      Provide  a  default  value for the internationalization vari-
                 ables that are unset or null. (See the Base Definitions  vol-
                 ume  of POSIX.1-2008, Section 8.2, Internationalization Vari-
                 ables 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
       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, applica-
       tions 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
       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
       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  vol-
       ume  of  POSIX.1-2008 specifies similar implementation-defined behavior
       for the basename and dirname utilities.
FUTURE DIRECTIONS
       None.
SEE ALSO
       Section 2.5, Parameters and Variables, dirname
       The Base Definitions volume of POSIX.1-2008, Section  3.267,  Pathname,
       Chapter 8, Environment Variables
COPYRIGHT
       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 Electri-
       cal  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.ker-
       nel.org/doc/man-pages/reporting_bugs.html .
IEEE/The Open Group                  2013                         BASENAME(1P)