+++ /dev/null
-'\"
-'\" Copyright (c) 1993 The Regents of the University of California.
-'\" Copyright (c) 1994-1996 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: @(#) Tcl.n 1.128 96/08/26 12:59:50
-'
-.so man.macros
-.TH Tcl n "" Tcl "Tcl Built-In Commands"
-.BS
-.SH NAME
-Tcl \- Summary of Tcl language syntax.
-.BE
-
-.SH DESCRIPTION
-.PP
-The following rules define the syntax and semantics of the Tcl language:
-.IP [1]
-A Tcl script is a string containing one or more commands.
-Semi-colons and newlines are command separators unless quoted as
-described below.
-Close brackets are command terminators during command substitution
-(see below) unless quoted.
-.IP [2]
-A command is evaluated in two steps.
-First, the Tcl interpreter breaks the command into \fIwords\fR
-and performs substitutions as described below.
-These substitutions are performed in the same way for all
-commands.
-The first word is used to locate a command procedure to
-carry out the command, then all of the words of the command are
-passed to the command procedure.
-The command procedure is free to interpret each of its words
-in any way it likes, such as an integer, variable name, list,
-or Tcl script.
-Different commands interpret their words differently.
-.IP [3]
-Words of a command are separated by white space (except for
-newlines, which are command separators).
-.IP [4]
-If the first character of a word is double-quote (``"'') then
-the word is terminated by the next double-quote character.
-If semi-colons, close brackets, or white space characters
-(including newlines) appear between the quotes then they are treated
-as ordinary characters and included in the word.
-Command substitution, variable substitution, and backslash substitution
-are performed on the characters between the quotes as described below.
-The double-quotes are not retained as part of the word.
-.IP [5]
-If the first character of a word is an open brace (``{'') then
-the word is terminated by the matching close brace (``}'').
-Braces nest within the word: for each additional open
-brace there must be an additional close brace (however,
-if an open brace or close brace within the word is
-quoted with a backslash then it is not counted in locating the
-matching close brace).
-No substitutions are performed on the characters between the
-braces except for backslash-newline substitutions described
-below, nor do semi-colons, newlines, close brackets,
-or white space receive any special interpretation.
-The word will consist of exactly the characters between the
-outer braces, not including the braces themselves.
-.IP [6]
-If a word contains an open bracket (``['') then Tcl performs
-\fIcommand substitution\fR.
-To do this it invokes the Tcl interpreter recursively to process
-the characters following the open bracket as a Tcl script.
-The script may contain any number of commands and must be terminated
-by a close bracket (``]'').
-The result of the script (i.e. the result of its last command) is
-substituted into the word in place of the brackets and all of the
-characters between them.
-There may be any number of command substitutions in a single word.
-Command substitution is not performed on words enclosed in braces.
-.IP [7]
-If a word contains a dollar-sign (``$'') then Tcl performs \fIvariable
-substitution\fR: the dollar-sign and the following characters are
-replaced in the word by the value of a variable.
-Variable substitution may take any of the following forms:
-.RS
-.TP 15
-\fB$\fIname\fR
-\fIName\fR is the name of a scalar variable; the name is terminated
-by any character that isn't a letter, digit, or underscore.
-.TP 15
-\fB$\fIname\fB(\fIindex\fB)\fR
-\fIName\fR gives the name of an array variable and \fIindex\fR gives
-the name of an element within that array.
-\fIName\fR must contain only letters, digits, and underscores.
-Command substitutions, variable substitutions, and backslash
-substitutions are performed on the characters of \fIindex\fR.
-.TP 15
-\fB${\fIname\fB}\fR
-\fIName\fR is the name of a scalar variable. It may contain any
-characters whatsoever except for close braces.
-.LP
-There may be any number of variable substitutions in a single word.
-Variable substitution is not performed on words enclosed in braces.
-.RE
-.IP [8]
-If a backslash (``\e'') appears within a word then
-\fIbackslash substitution\fR occurs.
-In all cases but those described below the backslash is dropped and
-the following character is treated as an ordinary
-character and included in the word.
-This allows characters such as double quotes, close brackets,
-and dollar signs to be included in words without triggering
-special processing.
-The following table lists the backslash sequences that are
-handled specially, along with the value that replaces each sequence.
-.RS
-.TP 6
-\e\fBa\fR
-Audible alert (bell) (0x7).
-.TP 6
-\e\fBb\fR
-Backspace (0x8).
-.TP 6
-\e\fBf\fR
-Form feed (0xc).
-.TP 6
-\e\fBn\fR
-Newline (0xa).
-.TP 6
-\e\fBr\fR
-Carriage-return (0xd).
-.TP 6
-\e\fBt\fR
-Tab (0x9).
-.TP 6
-\e\fBv\fR
-Vertical tab (0xb).
-.TP 6
-\e\fB<newline>\fIwhiteSpace\fR
-A single space character replaces the backslash, newline, and all
-spaces and tabs after the newline.
-This backslash sequence is unique in that it is replaced in a separate
-pre-pass before the command is actually parsed.
-This means that it will be replaced even when it occurs between
-braces, and the resulting space will be treated as a word separator
-if it isn't in braces or quotes.
-.TP 6
-\e\e
-Backslash (``\e'').
-.TP 6
-\e\fIooo\fR
-The digits \fIooo\fR (one, two, or three of them) give the octal value of
-the character.
-.TP 6
-\e\fBx\fIhh\fR
-The hexadecimal digits \fIhh\fR give the hexadecimal value of
-the character. Any number of digits may be present.
-.LP
-Backslash substitution is not performed on words enclosed in braces,
-except for backslash-newline as described above.
-.RE
-.IP [9]
-If a hash character (``#'') appears at a point where Tcl is
-expecting the first character of the first word of a command,
-then the hash character and the characters that follow it, up
-through the next newline, are treated as a comment and ignored.
-The comment character only has significance when it appears
-at the beginning of a command.
-.IP [10]
-Each character is processed exactly once by the Tcl interpreter
-as part of creating the words of a command.
-For example, if variable substitution occurs then no further
-substitutions are performed on the value of the variable; the
-value is inserted into the word verbatim.
-If command substitution occurs then the nested command is
-processed entirely by the recursive call to the Tcl interpreter;
-no substitutions are performed before making the recursive
-call and no additional substitutions are performed on the result
-of the nested script.
-.IP [11]
-Substitutions do not affect the word boundaries of a command.
-For example, during variable substitution the entire value of
-the variable becomes part of a single word, even if the variable's
-value contains spaces.
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