вернуть имя рабочего каталога (return working directory name)
Пролог (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.
Имя (Name)
pwd — return working directory name
Синопсис (Synopsis)
pwd [-L|-P]
Описание (Description)
The pwd utility shall write to standard output an absolute
pathname of the current working directory, which does not contain
the filenames dot or dot-dot.
Параметры (Options)
The pwd utility shall conform to the Base Definitions volume of
POSIX.1‐2017, Section 12.2, Utility Syntax Guidelines.
The following options shall be supported by the implementation:
-L If the PWD environment variable contains an absolute
pathname of the current directory and the pathname does
not contain any components that are dot or dot-dot, pwd
shall write this pathname to standard output, except
that if the PWD environment variable is longer than
{PATH_MAX} bytes including the terminating null, it is
unspecified whether pwd writes this pathname to
standard output or behaves as if the -P option had been
specified. Otherwise, the -L option shall behave as the
-P option.
-P The pathname written to standard output shall not
contain any components that refer to files of type
symbolic link. If there are multiple pathnames that the
pwd utility could write to standard output, one
beginning with a single <slash> character and one or
more beginning with two <slash> characters, then it
shall write the pathname beginning with a single
<slash> character. The pathname shall not contain any
unnecessary <slash> characters after the leading one or
two <slash> characters.
If both -L and -P are specified, the last one shall apply. If
neither -L nor -P is specified, the pwd utility shall behave as
if -L had been specified.
Операнды (Operands)
None.
Стандартный ввод (Stdin)
Not used.
Входные файлы (Input files)
None.
Переменные окружения (Environment variables)
The following environment variables shall affect the execution of
pwd:
LANG Provide a default value for the internationalization
variables that are unset or null. (See the Base
Definitions volume of POSIX.1‐2017, Section 8.2,
Internationalization Variables 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_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.
PWD An absolute pathname of the current working directory.
If an application sets or unsets the value of PWD, the
behavior of pwd is unspecified.
Асинхронные события (Asynchronous events)
Default.
Стандартный вывод (Stdout)
The pwd utility output is an absolute pathname of the current
working directory:
"%s\n", <directory pathname>
Стандартный вывод сообщений (Stderr)
The standard error shall be used only for diagnostic messages.
Выходные файлы (Output files)
None.
Расширенное описание (Extended description)
None.
Статус выхода (Exit)
The following exit values shall be returned:
0 Successful completion.
>0 An error occurred.
Последствия ошибок (Consequences of errors)
If an error is detected, output shall not be written to standard
output, a diagnostic message shall be written to standard error,
and the exit status is not zero.
The following sections are informative.
Использование в приложениях (Application usage)
If the pathname obtained from pwd is longer than {PATH_MAX}
bytes, it could produce an error if passed to cd. Therefore, in
order to return to that directory it may be necessary to break
the pathname into sections shorter than {PATH_MAX} and call cd on
each section in turn (the first section being an absolute
pathname and subsequent sections being relative pathnames).
Примеры (Examples)
None.
Обоснование (Rationale)
Some implementations have historically provided pwd as a shell
special built-in command.
In most utilities, if an error occurs, partial output may be
written to standard output. This does not happen in historical
implementations of pwd. Because pwd is frequently used in
historical shell scripts without checking the exit status, it is
important that the historical behavior is required here;
therefore, the CONSEQUENCES OF ERRORS section specifically
disallows any partial output being written to standard output.
An earlier version of this standard stated that the PWD
environment variable was affected when the -P option was in
effect. This was incorrect; conforming implementations do not do
this.
Будущие направления (Future directions)
None.
Смотри также (See also)
cd(1p)
The Base Definitions volume of POSIX.1‐2017, Chapter 8,
Environment Variables, Section 12.2, Utility Syntax Guidelines
The System Interfaces volume of POSIX.1‐2017, getcwd(3p)
