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+'\"
+'\" Copyright (c) 1995-1996 Sun Microsystems, Inc.
+'\"
+'\" See the file "license.terms" for information on usage and redistribution
+'\" of this file, and for a DISCLAIMER OF ALL WARRANTIES.
+'\" 
+'\" SCCS: @(#) filename.n 1.7 96/04/11 17:03:14
+'\" 
+.so man.macros
+.TH filename n 7.5 Tcl "Tcl Built-In Commands"
+.BS
+'\" Note:  do not modify the .SH NAME line immediately below!
+.SH NAME
+filename \- File name conventions supported by Tcl commands
+.BE
+.SH INTRODUCTION
+.PP
+All Tcl commands and C procedures that take file names as arguments
+expect the file names to be in one of three forms, depending on the
+current platform.  On each platform, Tcl supports file names in the
+standard forms(s) for that platform.  In addition, on all platforms,
+Tcl supports a Unix-like syntax intended to provide a convenient way
+of constructing simple file names.  However, scripts that are intended
+to be portable should not assume a particular form for file names.
+Instead, portable scripts must use the \fBfile split\fR and \fBfile
+join\fR commands to manipulate file names (see the \fBfile\fR manual
+entry for more details).
+
+.SH PATH TYPES
+.PP
+File names are grouped into three general types based on the starting point
+for the path used to specify the file: absolute, relative, and
+volume-relative.  Absolute names are completely qualified, giving a path to
+the file relative to a particular volume and the root directory on that
+volume.  Relative names are unqualified, giving a path to the file relative 
+to the current working directory.  Volume-relative names are partially
+qualified, either giving the path relative to the root directory on the
+current volume, or relative to the current directory of the specified
+volume.  The \fBfile pathtype\fR command can be used to determine the
+type of a given path.
+
+.SH PATH SYNTAX
+.PP
+The rules for native names depend on the value reported in the Tcl
+array element \fBtcl_platform(platform)\fR:
+.TP 10
+\fBmac\fR
+On Apple Macintosh systems, Tcl supports two forms of path names.  The
+normal Mac style names use colons as path separators.  Paths may be
+relative or absolute, and file names may contain any character other
+than colon.  A leading colon causes the rest of the path to be
+interpreted relative to the current directory.  If a path contains a
+colon that is not at the beginning, then the path is interpreted as an
+absolute path.  Sequences of two or more colons anywhere in the path
+are used to construct relative paths where \fB::\fR refers to the
+parent of the current directory, \fB:::\fR refers to the parent of the
+parent, and so forth.
+.RS
+.PP
+In addition to Macintosh style names, Tcl also supports a subset of
+Unix-like names.  If a path contains no colons, then it is interpreted
+like a Unix path.  Slash is used as the path separator.  The file name
+\fB\&.\fR refers to the current directory, and \fB\&..\fR refers to the
+parent of the current directory.  However, some names like \fB/\fR or
+\fB/..\fR have no mapping, and are interpreted as Macintosh names.  In
+general, commands that generate file names will return Macintosh style
+names, but commands that accept file names will take both Macintosh
+and Unix-style names.
+.PP
+The following examples illustrate various forms of path names:
+.TP 15
+\fB:\fR
+Relative path to the current folder.
+.TP 15
+\fBMyFile\fR
+Relative path to a file named \fBMyFile\fR in the current folder.
+.TP 15
+\fBMyDisk:MyFile\fR
+Absolute path to a file named \fBMyFile\fR on the device named \fBMyDisk\fR.
+.TP 15
+\fB:MyDir:MyFile\fR
+Relative path to a file name \fBMyFile\fR in a folder named
+\fBMyDir\fR in the current folder.
+.TP 15
+\fB::MyFile\fR
+Relative path to a file named \fBMyFile\fR in the folder above the
+current folder.
+.TP 15
+\fB:::MyFile\fR
+Relative path to a file named \fBMyFile\fR in the folder two levels above the
+current folder. 
+.TP 15
+\fB/MyDisk/MyFile\fR
+Absolute path to a file named \fBMyFile\fR on the device named
+\fBMyDisk\fR.
+.TP 15
+\fB\&../MyFile\fR
+Relative path to a file named \fBMyFile\fR in the folder above the
+current folder.
+.RE
+.TP
+\fBunix\fR
+On Unix 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
+\fB\&.\fR and \fB\&..\fR 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.
+The following examples illustrate various forms of path names:
+.RS
+.TP 15
+\fB/\fR
+Absolute path to the root directory.
+.TP 15
+\fB/etc/passwd\fR
+Absolute path to the file named \fBpasswd\fR in the directory
+\fBetc\fR in the root directory.
+.TP 15
+\fB\&.\fR
+Relative path to the current directory.
+.TP 15
+\fBfoo\fR
+Relative path to the file \fBfoo\fR in the current directory.
+.TP 15
+\fBfoo/bar\fR
+Relative path to the file \fBbar\fR in the directory \fBfoo\fR in the
+current directory.
+.TP 15
+\fB\&../foo\fR
+Relative path to the file \fBfoo\fR in the directory above the current
+directory. 
+.RE
+.TP
+\fBwindows\fR
+On Microsoft Windows platforms, Tcl supports both drive-relative and UNC
+style names.  Both \fB/\fR and \fB\e\fR 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 \fB\e\eservername\esharename\epath\efile\fR.  In both forms,
+the file names \fB.\fR and \fB..\fR 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:
+.RS
+.TP 15
+\fB\&\e\eHost\eshare/file\fR
+Absolute UNC path to a file called \fBfile\fR in the root directory of
+the export point \fBshare\fR on the host \fBHost\fR.
+.TP 15
+\fBc:foo\fR
+Volume-relative path to a file \fBfoo\fR in the current directory on drive
+\fBc\fR.
+.TP 15
+\fBc:/foo\fR
+Absolute path to a file \fBfoo\fR in the root directory of drive
+\fBc\fR.
+.TP 15
+\fBfoo\ebar\fR
+Relative path to a file \fBbar\fR in the \fBfoo\fR directory in the current
+directory on the current volume.
+.TP 15
+\fB\&\efoo\fR
+Volume-relative path to a file \fBfoo\fR in the root directory of the current
+volume.
+.RE
+
+.SH TILDE SUBSTITUTION
+.PP
+In addition to the file name rules described above, Tcl also supports
+\fIcsh\fR-style tilde substitution.  If a file name starts with a
+tilde, then the file name will be interpreted as if the first element
+is replaced with the location of the home directory for the given
+user.  If the tilde is followed immediately by a separator, then the
+\fB$HOME\fR environment variable is substituted.  Otherwise the
+characters between the tilde and the next separator are taken as a
+user name, which is used to retrieve the user's home directory for
+substitution.
+.PP
+The Macintosh and Windows platforms do not support tilde substitution
+when a user name follows the tilde.  On these platforms, attempts to
+use a tilde followed by a user name will generate an error.  File
+names that have a tilde without a user name will be substituted using
+the \fB$HOME\fR environment variable, just like for Unix.
+
+.SH PORTABILITY ISSUES
+.PP
+Not all file systems are case sensitive, so scripts should avoid code
+that depends on the case of characters in a file name.  In addition,
+the character sets allowed on different devices may differ, so scripts
+should choose file names that do not contain special characters like:
+\fB<>:"/\e|\fR.  The safest approach is to use names consisting of
+alphanumeric characters only.  Also Windows 3.1 only supports file
+names with a root of no more than 8 characters and an extension of no
+more than 3 characters.
+
+.SH KEYWORDS
+current directory, absolute file name, relative file name,
+volume-relative file name, portability