DIRNAME(1P)						     POSIX Programmer's Manual						       DIRNAME(1P)

PROLOG

       This  manual page is part of the POSIX Programmer's Manual.  The Linux implementation of this interface may differ (consult the correspond-
       ing Linux manual page for details of Linux behavior), or the interface may not be implemented on Linux.

NAME

       dirname - return the directory portion of a pathname

SYNOPSIS

       dirname string

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,  Path-
       name.  The  string string shall be converted to the name of the directory containing the filename corresponding to the last pathname compo-
       nent in string, performing actions equivalent to the following steps in order:

	1. If string is //, skip steps 2 to 5.

	2. If string consists entirely of slash characters, string shall be set to a single slash character. In this case, skip steps 3 to 8.

	3. If there are any trailing slash characters in string, they shall be removed.

	4. If there are no slash characters remaining in string, string shall be set to a single period character. In this case, skip steps  5	to
	   8.

	5. If there are any trailing non-slash characters in string, they shall be removed.

	6. If the remaining string is //, it is implementation-defined whether steps 7 and 8 are skipped or processed.

	7. If there are any trailing slash characters in string, they shall be removed.

	8. If the remaining string is empty, string shall be set to a single slash character.

       The resulting string shall be written to standard output.

OPTIONS

       None.

OPERANDS

       The following operand shall be supported:

       string A string.

STDIN

       Not used.

INPUT FILES

       None.

ENVIRONMENT VARIABLES

       The following environment variables shall affect the execution of dirname:

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

	      "%s
", <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 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

							     Command		Results
							     dirname /		/
							     dirname // 	/ or //
							     dirname /a/b/	/a
							     dirname //a//b//	//a
							     dirname		Unspecified
							     dirname a		. ($? = 0)
							     dirname "" 	. ($? = 0)
							     dirname /a 	/
							     dirname /a/b	/a
							     dirname a/b	a

RATIONALE

       The dirname utility originated in System III. It has evolved through the System V releases to a version that matches the requirements spec-
       ified in this description in System V Release 3.  4.3 BSD and earlier versions did not include dirname.

       The behaviors of basename and dirname in this volume of IEEE Std 1003.1-2001 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 versions of these utilities in early proposals due to the way processing of trailing slashes was specified.
       Consideration was given to leaving processing unspecified if there were trailing slashes, but this cannot be  done;  the  Base  Definitions
       volume of IEEE Std 1003.1-2001, Section 3.266, Pathname allows trailing slashes. The basename and dirname utilities have to specify consis-
       tent handling for all valid pathnames.

FUTURE DIRECTIONS

       None.

SEE ALSO

       basename(), Parameters and Variables

COPYRIGHT

       Portions of this text are reprinted and reproduced in electronic form from IEEE Std 1003.1, 2003 Edition, Standard for Information Technol-
       ogy -- Portable Operating System Interface (POSIX), The Open Group Base Specifications Issue 6, Copyright (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.opengroup.org/unix/online.html .

IEEE
/The Open Group						       2003							       DIRNAME(1P)