145 lines
5.0 KiB
TeX
145 lines
5.0 KiB
TeX
\section{Standard Module \sectcode{posixpath}}
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\stmodindex{posixpath}
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This module implements some useful functions on POSIX pathnames.
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\strong{Do not import this module directly.} Instead, import the
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module \code{os} and use \code{os.path}.
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\stmodindex{os}
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\renewcommand{\indexsubitem}{(in module posixpath)}
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\begin{funcdesc}{basename}{p}
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Return the base name of pathname
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\var{p}.
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This is the second half of the pair returned by
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\code{posixpath.split(\var{p})}.
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\end{funcdesc}
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\begin{funcdesc}{commonprefix}{list}
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Return the longest string that is a prefix of all strings in
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\var{list}.
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If
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\var{list}
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is empty, return the empty string (\code{''}).
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\end{funcdesc}
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\begin{funcdesc}{exists}{p}
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Return true if
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\var{p}
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refers to an existing path.
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\end{funcdesc}
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\begin{funcdesc}{expanduser}{p}
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Return the argument with an initial component of \samp{\~} or
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\samp{\~\var{user}} replaced by that \var{user}'s home directory. An
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initial \samp{\~{}} is replaced by the environment variable \code{\${}HOME};
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an initial \samp{\~\var{user}} is looked up in the password directory through
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the built-in module \code{pwd}. If the expansion fails, or if the
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path does not begin with a tilde, the path is returned unchanged.
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\end{funcdesc}
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\begin{funcdesc}{expandvars}{p}
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Return the argument with environment variables expanded. Substrings
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of the form \samp{\$\var{name}} or \samp{\$\{\var{name}\}} are
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replaced by the value of environment variable \var{name}. Malformed
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variable names and references to non-existing variables are left
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unchanged.
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\end{funcdesc}
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\begin{funcdesc}{isabs}{p}
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Return true if \var{p} is an absolute pathname (begins with a slash).
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\end{funcdesc}
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\begin{funcdesc}{isfile}{p}
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Return true if \var{p} is an existing regular file. This follows
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symbolic links, so both \code{islink()} and \code{isfile()} can be true for the same
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path.
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\end{funcdesc}
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\begin{funcdesc}{isdir}{p}
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Return true if \var{p} is an existing directory. This follows
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symbolic links, so both \code{islink()} and \code{isdir()} can be true for the same
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path.
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\end{funcdesc}
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\begin{funcdesc}{islink}{p}
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Return true if
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\var{p}
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refers to a directory entry that is a symbolic link.
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Always false if symbolic links are not supported.
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\end{funcdesc}
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\begin{funcdesc}{ismount}{p}
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Return true if pathname \var{p} is a \dfn{mount point}: a point in a
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file system where a different file system has been mounted. The
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function checks whether \var{p}'s parent, \file{\var{p}/..}, is on a
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different device than \var{p}, or whether \file{\var{p}/..} and
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\var{p} point to the same i-node on the same device --- this should
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detect mount points for all \UNIX{} and POSIX variants.
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\end{funcdesc}
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\begin{funcdesc}{join}{p\, q}
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Join the paths
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\var{p}
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and
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\var{q} intelligently:
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If
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\var{q}
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is an absolute path, the return value is
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\var{q}.
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Otherwise, the concatenation of
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\var{p}
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and
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\var{q}
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is returned, with a slash (\code{'/'}) inserted unless
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\var{p}
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is empty or ends in a slash.
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\end{funcdesc}
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\begin{funcdesc}{normcase}{p}
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Normalize the case of a pathname. This returns the path unchanged;
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however, a similar function in \code{macpath} converts upper case to
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lower case.
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\end{funcdesc}
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\begin{funcdesc}{samefile}{p\, q}
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Return true if both pathname arguments refer to the same file or directory
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(as indicated by device number and i-node number).
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Raise an exception if a stat call on either pathname fails.
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\end{funcdesc}
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\begin{funcdesc}{split}{p}
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Split the pathname \var{p} in a pair \code{(\var{head}, \var{tail})},
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where \var{tail} is the last pathname component and \var{head} is
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everything leading up to that. The \var{tail} part will never contain
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a slash; if \var{p} ends in a slash, \var{tail} will be empty. If
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there is no slash in \var{p}, \var{head} will be empty. If \var{p} is
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empty, both \var{head} and \var{tail} are empty. Trailing slashes are
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stripped from \var{head} unless it is the root (one or more slashes
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only). In nearly all cases, \code{join(\var{head}, \var{tail})}
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equals \var{p} (the only exception being when there were multiple
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slashes separating \var{head} from \var{tail}).
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\end{funcdesc}
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\begin{funcdesc}{splitext}{p}
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Split the pathname \var{p} in a pair \code{(\var{root}, \var{ext})}
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such that \code{\var{root} + \var{ext} == \var{p}},
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and \var{ext} is empty or begins with a period and contains
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at most one period.
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\end{funcdesc}
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\begin{funcdesc}{walk}{p\, visit\, arg}
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Calls the function \var{visit} with arguments
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\code{(\var{arg}, \var{dirname}, \var{names})} for each directory in the
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directory tree rooted at \var{p} (including \var{p} itself, if it is a
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directory). The argument \var{dirname} specifies the visited directory,
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the argument \var{names} lists the files in the directory (gotten from
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\code{posix.listdir(\var{dirname})}, so including \samp{.} and
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\samp{..}). The \var{visit} function may modify \var{names} to
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influence the set of directories visited below \var{dirname}, e.g., to
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avoid visiting certain parts of the tree. (The object referred to by
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\var{names} must be modified in place, using \code{del} or slice
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assignment.)
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\end{funcdesc}
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