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 (con-
       sult 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 IEEE Std 1003.1-2001,
       Section 3.266, Pathname. The string string shall be converted to the filename corresponding to the last  pathname  compo-
       nent  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  char-
           acter 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 suf-
           fix 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
       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 internationalization 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  international-
              ization 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 stan-
              dard 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 arbitrarily 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 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
       slashes.

       Since  the definition of pathname specifies implementation-defined behavior for pathnames starting with two slash charac-
       ters, 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 Operating System Interface (POSIX), The Open Group Base Specifications Issue 6,  Copy-
       right (C) 2001-2003 by the Institute 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.open-
       group.org/unix/online.html .



IEEE/The Open Group                                           2003                                                  BASENAME(1P)