# cpython-withatomic / Doc / libppath.tex

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  1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 \section{Standard Module \sectcode{posixpath}} \stmodindex{posixpath} This module implements some useful functions on POSIX pathnames. \renewcommand{\indexsubitem}{(in module posixpath)} \begin{funcdesc}{basename}{p} Return the base name of pathname \var{p}. This is the second half of the pair returned by \code{posixpath.split(\var{p})}. \end{funcdesc} \begin{funcdesc}{commonprefix}{list} Return the longest string that is a prefix of all strings in \var{list}. If \var{list} is empty, return the empty string (\code{''}). \end{funcdesc} \begin{funcdesc}{exists}{p} Return true if \var{p} refers to an existing path. \end{funcdesc} \begin{funcdesc}{expanduser}{p} Return the argument with an initial component of \samp{\~} or \samp{\~\var{user}} replaced by that \var{user}'s home directory. An initial \samp{\~{}} is replaced by the environment variable \code{\${}HOME}; an initial \samp{\~\var{user}} is looked up in the password directory through the built-in module \code{pwd}. If the expansion fails, or if the path does not begin with a tilde, the path is returned unchanged. \end{funcdesc} \begin{funcdesc}{expandvars}{p} Return the argument with environment variables expanded. Substrings of the form \samp{\$\var{name}} or \samp{\\$\{\var{name}\}} are replaced by the value of environment variable \var{name}. Malformed variable names and references to non-existing variables are left unchanged. \end{funcdesc} \begin{funcdesc}{isabs}{p} Return true if \var{p} is an absolute pathname (begins with a slash). \end{funcdesc} \begin{funcdesc}{isfile}{p} Return true if \var{p} is an existing regular file. This follows symbolic links, so both islink() and isfile() can be true for the same path. \end{funcdesc} \begin{funcdesc}{isdir}{p} Return true if \var{p} is an existing directory. This follows symbolic links, so both islink() and isdir() can be true for the same path. \end{funcdesc} \begin{funcdesc}{islink}{p} Return true if \var{p} refers to a directory entry that is a symbolic link. Always false if symbolic links are not supported. \end{funcdesc} \begin{funcdesc}{ismount}{p} Return true if \var{p} is a mount point. (This currently checks whether \code{\var{p}/..} is on a different device from \var{p} or whether \code{\var{p}/..} and \var{p} point to the same i-node on the same device --- is this test correct for all \UNIX{} and POSIX variants?) \end{funcdesc} \begin{funcdesc}{join}{p\, q} Join the paths \var{p} and \var{q} intelligently: If \var{q} is an absolute path, the return value is \var{q}. Otherwise, the concatenation of \var{p} and \var{q} is returned, with a slash (\code{'/'}) inserted unless \var{p} is empty or ends in a slash. \end{funcdesc} \begin{funcdesc}{normcase}{p} Normalize the case of a pathname. This returns the path unchanged; however, a similar function in \code{macpath} converts upper case to lower case. \end{funcdesc} \begin{funcdesc}{samefile}{p\, q} Return true if both pathname arguments refer to the same file or directory (as indicated by device number and i-node number). Raise an exception if a stat call on either pathname fails. \end{funcdesc} \begin{funcdesc}{split}{p} Split the pathname \var{p} in a pair \code{(\var{head}, \var{tail})}, where \var{tail} is the last pathname component and \var{head} is everything leading up to that. If \var{p} ends in a slash (except if it is the root), the trailing slash is removed and the operation applied to the result; otherwise, \code{join(\var{head}, \var{tail})} equals \var{p}. The \var{tail} part never contains a slash. Some boundary cases: if \var{p} is the root, \var{head} equals \var{p} and \var{tail} is empty; if \var{p} is empty, both \var{head} and \var{tail} are empty; if \var{p} contains no slash, \var{head} is empty and \var{tail} equals \var{p}. \end{funcdesc} \begin{funcdesc}{splitext}{p} Split the pathname \var{p} in a pair \code{(\var{root}, \var{ext})} such that \code{\var{root} + \var{ext} == \var{p}}, the last component of \var{root} contains no periods, and \var{ext} is empty or begins with a period. \end{funcdesc} \begin{funcdesc}{walk}{p\, visit\, arg} Calls the function \var{visit} with arguments \code{(\var{arg}, \var{dirname}, \var{names})} for each directory in the directory tree rooted at \var{p} (including \var{p} itself, if it is a directory). The argument \var{dirname} specifies the visited directory, the argument \var{names} lists the files in the directory (gotten from \code{posix.listdir(\var{dirname})}). The \var{visit} function may modify \var{names} to influence the set of directories visited below \var{dirname}, e.g., to avoid visiting certain parts of the tree. (The object referred to by \var{names} must be modified in place, using \code{del} or slice assignment.) \end{funcdesc}