Originální popis anglicky:
dirname - return the directory portion of a pathname
Návod, kniha: POSIX Programmer's Manual
dirname string
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 name of the
directory containing the filename corresponding to the last pathname component
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.
None.
The following operand shall be supported:
- string
- A string.
Not used.
None.
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 .
Default.
The
dirname 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 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.
| 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 |
The
dirname utility originated in System III. It has evolved through the
System V releases to a version that matches the requirements specified 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:
would be a valid filename for the file in the directory:
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
consistent handling for all valid pathnames.
None.
basename() ,
Parameters and Variables
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, 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
.
