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+'\"
+'\" Copyright (c) 1991-1993 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: @(#) library.n 1.23 96/11/20 14:07:04
+.so man.macros
+.TH library n "8.0" Tcl "Tcl Built-In Commands"
+.BS
+.SH NAME
+library \- standard library of Tcl procedures
+.SH SYNOPSIS
+.nf
+\fBauto_execok \fIcmd\fR
+\fBauto_load \fIcmd\fR
+\fBauto_mkindex \fIdir pattern pattern ...\fR
+\fBauto_reset\fR
+\fBparray \fIarrayName\fR
+.VS
+\fBtcl_endOfWord \fIstr start\fR
+\fBtcl_startOfNextWord \fIstr start\fR
+\fBtcl_startOfPreviousWord \fIstr start\fR
+\fBtcl_wordBreakAfter \fIstr start\fR
+\fBtcl_wordBreakBefore \fIstr start\fR
+.VE
+.BE
+
+.SH INTRODUCTION
+.PP
+Tcl includes a library of Tcl procedures for commonly-needed functions.
+The procedures defined in the Tcl library are generic ones suitable
+for use by many different applications.
+The location of the Tcl library is returned by the \fBinfo library\fR
+command.
+In addition to the Tcl library, each application will normally have
+its own library of support procedures as well;  the location of this
+library is normally given by the value of the \fB$\fIapp\fB_library\fR
+global variable, where \fIapp\fR is the name of the application.
+For example, the location of the Tk library is kept in the variable
+\fB$tk_library\fR.
+.PP
+To access the procedures in the Tcl library, an application should
+source the file \fBinit.tcl\fR in the library, for example with
+the Tcl command
+.CS
+\fBsource [file join [info library] init.tcl]\fR
+.CE
+If the library procedure \fBTcl_Init\fR is invoked from an application's
+\fBTcl_AppInit\fR procedure, this happens automatically.
+The code in \fBinit.tcl\fR will define the \fBunknown\fR procedure
+and arrange for the other procedures to be loaded on-demand using
+the auto-load mechanism defined below.
+
+.SH "COMMAND PROCEDURES"
+.PP
+The following procedures are provided in the Tcl library:
+.TP
+\fBauto_execok \fIcmd\fR
+Determines whether there is an executable file by the name \fIcmd\fR.
+This command examines the directories in the current search path
+(given by the PATH environment variable) to see if there is an
+executable file named \fIcmd\fR in any of those directories.
+If so, it returns 1;  if not it returns 0.  \fBAuto_exec\fR
+remembers information about previous searches in an array
+named \fBauto_execs\fR;  this avoids the path search in
+future calls for the same \fIcmd\fR.  The command \fBauto_reset\fR
+may be used to force \fBauto_execok\fR to forget its cached
+information.
+.TP
+\fBauto_load \fIcmd\fR
+This command attempts to load the definition for a Tcl command named
+\fIcmd\fR.
+To do this, it searches an \fIauto-load path\fR, which is a list of
+one or more directories.
+The auto-load path is given by the global variable \fB$auto_path\fR
+if it exists.
+If there is no \fB$auto_path\fR variable, then the TCLLIBPATH environment
+variable is used, if it exists.
+Otherwise the auto-load path consists of just the Tcl library directory.
+Within each directory in the auto-load path there must be a file
+\fBtclIndex\fR that describes one
+or more commands defined in that directory
+and a script to evaluate to load each of the commands.
+The \fBtclIndex\fR file should be generated with the
+\fBauto_mkindex\fR command.
+If \fIcmd\fR is found in an index file, then the appropriate
+script is evaluated to create the command.
+The \fBauto_load\fR command returns 1 if \fIcmd\fR was successfully
+created.
+The command returns 0 if there was no index entry for \fIcmd\fR
+or if the script didn't actually define \fIcmd\fR (e.g. because
+index information is out of date).
+If an error occurs while processing the script, then that error
+is returned.
+\fBAuto_load\fR only reads the index information once and saves it
+in the array \fBauto_index\fR;  future calls to \fBauto_load\fR
+check for \fIcmd\fR in the array rather than re-reading the index
+files.
+The cached index information may be deleted with the command
+\fBauto_reset\fR.
+This will force the next \fBauto_load\fR command to reload the
+index database from disk.
+.TP
+\fBauto_mkindex \fIdir pattern pattern ...\fR
+Generates an index suitable for use by \fBauto_load\fR.
+The command searches \fIdir\fR for all files whose names match
+any of the \fIpattern\fR arguments
+(matching is done with the \fBglob\fR command),
+generates an index of all the Tcl command
+procedures defined in all the matching files, and stores the
+index information in a file named \fBtclIndex\fR in \fIdir\fR.
+If no pattern is given a pattern of \fB*.tcl\fR will be assumed.  
+For example, the command
+.RS
+.CS
+\fBauto_mkindex foo *.tcl\fR
+.CE
+.LP
+will read all the \fB.tcl\fR files in subdirectory \fBfoo\fR
+and generate a new index file \fBfoo/tclIndex\fR.
+.PP
+\fBAuto_mkindex\fR parses the Tcl scripts in a relatively
+unsophisticated way:  if any line contains the word \fBproc\fR
+as its first characters then it is assumed to be a procedure
+definition and the next word of the line is taken as the
+procedure's name.
+Procedure definitions that don't appear in this way (e.g. they
+have spaces before the \fBproc\fR) will not be indexed.
+.RE
+.TP
+\fBauto_reset\fR
+Destroys all the information cached by \fBauto_execok\fR and
+\fBauto_load\fR.
+This information will be re-read from disk the next time it is
+needed.
+\fBAuto_reset\fR also deletes any procedures listed in the auto-load
+index, so that fresh copies of them will be loaded the next time
+that they're used.
+.TP
+\fBparray \fIarrayName\fR
+Prints on standard output the names and values of all the elements
+in the array \fIarrayName\fR.
+\fBArrayName\fR must be an array accessible to the caller of \fBparray\fR.
+It may be either local or global.
+.TP
+\fBtcl_endOfWord \fIstr start\fR
+.VS
+Returns the index of the first end-of-word location that occurs after
+a starting index \fIstart\fR in the string \fIstr\fR.  An end-of-word
+location is defined to be the first non-word character following the
+first word character after the starting point.  Returns -1 if there
+are no more end-of-word locations after the starting point.  See the
+description of \fBtcl_wordchars\fR and \fBtcl_nonwordchars\fR below
+for more details on how Tcl determines which characters are word
+characters.
+.TP
+\fBtcl_startOfNextWord \fIstr start\fR
+Returns the index of the first start-of-word location that occurs
+after a starting index \fIstart\fR in the string \fIstr\fR.  A
+start-of-word location is defined to be the first word character
+following a non-word character.  Returns \-1 if there are no more
+start-of-word locations after the starting point.
+.TP
+\fBtcl_startOfPreviousWord \fIstr start\fR
+Returns the index of the first start-of-word location that occurs
+before a starting index \fIstart\fR in the string \fIstr\fR.  Returns
+\-1 if there are no more start-of-word locations before the starting
+point.
+.TP
+\fBtcl_wordBreakAfter \fIstr start\fR
+Returns the index of the first word boundary after the starting index
+\fIstart\fR in the string \fIstr\fR.  Returns \-1 if there are no more
+boundaries after the starting point in the given string.  The index
+returned refers to the second character of the pair that comprises a
+boundary.
+.TP
+\fBtcl_wordBreakBefore \fIstr start\fR
+Returns the index of the first word boundary before the starting index
+\fIstart\fR in the string \fIstr\fR.  Returns \-1 if there are no more
+boundaries before the starting point in the given string.  The index
+returned refers to the second character of the pair that comprises a
+boundary.
+.VE
+
+.SH "VARIABLES"
+.PP
+The following global variables are defined or used by the procedures in
+the Tcl library:
+.TP
+\fBauto_execs\fR
+Used by \fBauto_execok\fR to record information about whether
+particular commands exist as executable files.
+.TP
+\fBauto_index\fR
+Used by \fBauto_load\fR to save the index information read from
+disk.
+.TP
+\fBauto_noexec\fR
+If set to any value, then \fBunknown\fR will not attempt to auto-exec
+any commands.
+.TP
+\fBauto_noload\fR
+If set to any value, then \fBunknown\fR will not attempt to auto-load
+any commands.
+.TP
+\fBauto_path\fR
+If set, then it must contain a valid Tcl list giving directories to
+search during auto-load operations.
+.TP
+\fBenv(TCL_LIBRARY)\fR
+If set, then it specifies the location of the directory containing
+library scripts (the value of this variable will be returned by
+the command \fBinfo library\fR).  If this variable isn't set then
+a default value is used.
+.TP
+\fBenv(TCLLIBPATH)\fR
+If set, then it must contain a valid Tcl list giving directories to
+search during auto-load operations.
+This variable is only used if \fBauto_path\fR is not defined.
+.TP
+\fBtcl_nonwordchars\fR
+.VS
+This variable contains a regular expression that is used by routines
+like \fBtcl_endOfWord\fR to identify whether a character is part of a
+word or not.  If the pattern matches a character, the character is
+considered to be a non-word character.  On Windows platforms, spaces,
+tabs, and newlines are considered non-word characters.  Under Unix,
+everything but numbers, letters and underscores are considered
+non-word characters.
+.TP
+\fBtcl_wordchars\fR
+This variable contains a regular expression that is used by routines
+like \fBtcl_endOfWord\fR to identify whether a character is part of a
+word or not.  If the pattern matches a character, the character is
+considered to be a word character.  On Windows platforms, words are
+comprised of any character that is not a space, tab, or newline.  Under
+Unix, words are comprised of numbers, letters or underscores.
+.VE
+.TP
+\fBunknown_active\fR
+This variable is set by \fBunknown\fR to indicate that it is active.
+It is used to detect errors where \fBunknown\fR recurses on itself
+infinitely.
+The variable is unset before \fBunknown\fR returns.
+
+.SH KEYWORDS
+auto-exec, auto-load, library, unknown, word, whitespace