Tcl/Tk Documentation > TclCmd > filename
- filename - File name conventions supported by Tcl commands
- PATH TYPES
- PATH SYNTAX
- TILDE SUBSTITUTION
- PORTABILITY ISSUES
- SEE ALSO
- On Unix and Apple MacOS X platforms, Tcl uses path names where
the components are separated by slashes. Path names may be relative
or absolute, and file names may contain any character other than
slash. The file names . and .. are special and refer
to the current directory and the parent of the current directory
respectively. Multiple adjacent slash characters are interpreted as
a single separator. Any number of trailing slash characters at the
end of a path are simply ignored, so the paths foo,
foo/ and foo// are all identical, and in particular
foo/ does not necessarily mean a directory is being
The following examples illustrate various forms of path names:
- Absolute path to the root directory.
- Absolute path to the file named passwd in the directory etc in the root directory.
- Relative path to the current directory.
- Relative path to the file foo in the current directory.
- Relative path to the file bar in the directory foo in the current directory.
- Relative path to the file foo in the directory above the current directory.
- On Microsoft Windows platforms, Tcl supports both
drive-relative and UNC style names. Both / and \ may
be used as directory separators in either type of name.
Drive-relative names consist of an optional drive specifier
followed by an absolute or relative path. UNC paths follow the
general form \\servername\sharename\path\file, but must at
the very least contain the server and share components, i.e.
\\servername\sharename. In both forms, the file names
. and .. are special and refer to the current
directory and the parent of the current directory respectively. The
following examples illustrate various forms of path names:
- Absolute UNC path to a file called file in the root directory of the export point share on the host Host. Note that repeated use of file dirname on this path will give //Host/share, and will never give just //Host.
- Volume-relative path to a file foo in the current directory on drive c.
- Absolute path to a file foo in the root directory of drive c.
- Relative path to a file bar in the foo directory in the current directory on the current volume.
- Volume-relative path to a file foo in the root directory of the current volume.
- Volume-relative path to a file foo in the root directory of the current volume. This is not a valid UNC path, so the assumption is that the extra backslashes are superfluous.
Old Windows platforms do not support tilde substitution when a user name follows the tilde. On these platforms, attempts to use a tilde followed by a user name will generate an error that the user does not exist when Tcl attempts to interpret that part of the path or otherwise access the file. The behaviour of these paths when not trying to interpret them is the same as on Unix. File names that have a tilde without a user name will be correctly substituted using the $HOME environment variable, just like for Unix.
On Windows platforms there are file and path length restrictions. Complete paths or filenames longer than about 260 characters will lead to errors in most file operations.
Another Windows peculiarity is that any number of trailing dots “.” in filenames are totally ignored, so, for example, attempts to create a file or directory with a name “foo.” will result in the creation of a file/directory with name “foo”. This fact is reflected in the results of file normalize. Furthermore, a file name consisting only of dots “.........” or dots with trailing characters “.....abc” is illegal.file, glob current directory, absolute file name, relative file name, volume-relative file name, portability