9.10. Splitting a Filename into Its Component Parts9.10.1. ProblemYou want to extract a filename, its enclosing directory, or the extension(s) from a string that contains a full pathname. 9.10.2. SolutionUse routines from the standard File::Basename module. use File::Basename; $base = basename($path); $dir = dirname($path); ($base, $dir, $ext) = fileparse($path); 9.10.3. DiscussionThe standard File::Basename module contains routines to split up a filename. dirname and basename supply the directory and filename portions, respectively: $path = "/usr/lib/libc.a"; $file = basename($path); $dir = dirname($path); print "dir is $dir, file is $file\n"; # dir is /usr/lib, file is libc.a The fileparse function can extract the extension. Pass fileparse the path to decipher and a regular expression that matches the extension. You must supply a pattern because an extension isn't necessarily dot-separated. Consider ".tar.gz": is the extension ".tar", ".gz", or ".tar.gz"? By specifying the pattern, you control which you get. $path = "/usr/lib/libc.a"; ($name,$dir,$ext) = fileparse($path,'\..*'); print "dir is $dir, name is $name, extension is $ext\n"; # dir is /usr/lib/, name is libc, extension is .a By default, these routines parse pathnames using your operating system's normal conventions for directory separators by consulting the $^O ($OSNAME) variable, which holds a string identifying the platform you're running on. That value was determined when Perl was built and installed. You can change the default by calling the fileparse_set_fstype routine. This alters the behavior of subsequent calls to the File::Basename functions: fileparse_set_fstype("MacOS"); $path = "Hard%20Drive:System%20Folder:README.txt"; ($name,$dir,$ext) = fileparse($path,'\..*'); print "dir is $dir, name is $name, extension is $ext\n"; # dir is Hard%20Drive:System%20Folder, name is README, extension is .txt To pull out just the extension, you might use this: sub extension { my $path = shift; my $ext = (fileparse($path,'\..*'))[2]; $ext =~ s/^\.//; return $ext; } When called on a file like source.c.bak, this returns an extension of "c.bak", not just "bak". If you want ".bak" returned, use '\.[^.]*' as the second argument to fileparse (this will, of course, leave the filename as source.c). When passed a pathname with a trailing directory separator, such as "lib/", fileparse considers the directory name to be "lib/", whereas dirname considers it to be ".". 9.10.4. See AlsoThe documentation for the standard File::Basename module (also in Chapter 32 of Programming Perl); the entry for $^O ($OSNAME) in perlvar(1), and in the "Special Variables in Alphabetical Order" section of Chapter 28 of Programming Perl Copyright © 2003 O'Reilly & Associates. All rights reserved. |
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