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diff --git a/doc/filename.n b/doc/filename.n new file mode 100644 index 0000000..e1f38ae --- /dev/null +++ b/doc/filename.n @@ -0,0 +1,197 @@ +'\" +'\" 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 |