'\" '\" 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: @(#) tclvars.n 1.15 96/04/12 08:28:20 '\" '\" The definitions below are for supplemental macros used in Tcl/Tk '\" manual entries. '\" '\" .AP type name in/out ?indent? '\" Start paragraph describing an argument to a library procedure. '\" type is type of argument (int, etc.), in/out is either "in", "out", '\" or "in/out" to describe whether procedure reads or modifies arg, '\" and indent is equivalent to second arg of .IP (shouldn't ever be '\" needed; use .AS below instead) '\" '\" .AS ?type? ?name? '\" Give maximum sizes of arguments for setting tab stops. Type and '\" name are examples of largest possible arguments that will be passed '\" to .AP later. If args are omitted, default tab stops are used. '\" '\" .BS '\" Start box enclosure. From here until next .BE, everything will be '\" enclosed in one large box. '\" '\" .BE '\" End of box enclosure. '\" '\" .CS '\" Begin code excerpt. '\" '\" .CE '\" End code excerpt. '\" '\" .VS ?br? '\" Begin vertical sidebar, for use in marking newly-changed parts '\" of man pages. If an argument is present, then a line break is '\" forced before starting the sidebar. '\" '\" .VE '\" End of vertical sidebar. '\" '\" .DS '\" Begin an indented unfilled display. '\" '\" .DE '\" End of indented unfilled display. '\" '\" .SO '\" Start of list of standard options for a Tk widget. The '\" options follow on successive lines, in four columns separated '\" by tabs. '\" '\" .SE '\" End of list of standard options for a Tk widget. '\" '\" .OP cmdName dbName dbClass '\" Start of description of a specific option. cmdName gives the '\" option's name as specified in the class command, dbName gives '\" the option's name in the option database, and dbClass gives '\" the option's class in the option database. '\" '\" .UL arg1 arg2 '\" Print arg1 underlined, then print arg2 normally. '\" '\" SCCS: @(#) man.macros 1.8 96/02/15 20:02:24 '\" '\" # Set up traps and other miscellaneous stuff for Tcl/Tk man pages. .if t .wh -1.3i ^B .nr ^l \n(.l .ad b '\" # Start an argument description .de AP .ie !"\\$4"" .TP \\$4 .el \{\ . ie !"\\$2"" .TP \\n()Cu . el .TP 15 .\} .ie !"\\$3"" \{\ .ta \\n()Au \\n()Bu \&\\$1 \\fI\\$2\\fP (\\$3) .\".b .\} .el \{\ .br .ie !"\\$2"" \{\ \&\\$1 \\fI\\$2\\fP .\} .el \{\ \&\\fI\\$1\\fP .\} .\} .. '\" # define tabbing values for .AP .de AS .nr )A 10n .if !"\\$1"" .nr )A \\w'\\$1'u+3n .nr )B \\n()Au+15n .\" .if !"\\$2"" .nr )B \\w'\\$2'u+\\n()Au+3n .nr )C \\n()Bu+\\w'(in/out)'u+2n .. .AS Tcl_Interp Tcl_CreateInterp in/out '\" # BS - start boxed text '\" # ^y = starting y location '\" # ^b = 1 .de BS .br .mk ^y .nr ^b 1u .if n .nf .if n .ti 0 .if n \l'\\n(.lu\(ul' .if n .fi .. '\" # BE - end boxed text (draw box now) .de BE .nf .ti 0 .mk ^t .ie n \l'\\n(^lu\(ul' .el \{\ .\" Draw four-sided box normally, but don't draw top of .\" box if the box started on an earlier page. .ie !\\n(^b-1 \{\ \h'-1.5n'\L'|\\n(^yu-1v'\l'\\n(^lu+3n\(ul'\L'\\n(^tu+1v-\\n(^yu'\l'|0u-1.5n\(ul' .\} .el \}\ \h'-1.5n'\L'|\\n(^yu-1v'\h'\\n(^lu+3n'\L'\\n(^tu+1v-\\n(^yu'\l'|0u-1.5n\(ul' .\} .\} .fi .br .nr ^b 0 .. '\" # VS - start vertical sidebar '\" # ^Y = starting y location '\" # ^v = 1 (for troff; for nroff this doesn't matter) .de VS .if !"\\$1"" .br .mk ^Y .ie n 'mc \s12\(br\s0 .el .nr ^v 1u .. '\" # VE - end of vertical sidebar .de VE .ie n 'mc .el \{\ .ev 2 .nf .ti 0 .mk ^t \h'|\\n(^lu+3n'\L'|\\n(^Yu-1v\(bv'\v'\\n(^tu+1v-\\n(^Yu'\h'-|\\n(^lu+3n' .sp -1 .fi .ev .\} .nr ^v 0 .. '\" # Special macro to handle page bottom: finish off current '\" # box/sidebar if in box/sidebar mode, then invoked standard '\" # page bottom macro. .de ^B .ev 2 'ti 0 'nf .mk ^t .if \\n(^b \{\ .\" Draw three-sided box if this is the box's first page, .\" draw two sides but no top otherwise. .ie !\\n(^b-1 \h'-1.5n'\L'|\\n(^yu-1v'\l'\\n(^lu+3n\(ul'\L'\\n(^tu+1v-\\n(^yu'\h'|0u'\c .el \h'-1.5n'\L'|\\n(^yu-1v'\h'\\n(^lu+3n'\L'\\n(^tu+1v-\\n(^yu'\h'|0u'\c .\} .if \\n(^v \{\ .nr ^x \\n(^tu+1v-\\n(^Yu \kx\h'-\\nxu'\h'|\\n(^lu+3n'\ky\L'-\\n(^xu'\v'\\n(^xu'\h'|0u'\c .\} .bp 'fi .ev .if \\n(^b \{\ .mk ^y .nr ^b 2 .\} .if \\n(^v \{\ .mk ^Y .\} .. '\" # DS - begin display .de DS .RS .nf .sp .. '\" # DE - end display .de DE .fi .RE .sp .. '\" # SO - start of list of standard options .de SO .SH "STANDARD OPTIONS" .LP .nf .ta 4c 8c 12c .ft B .. '\" # SE - end of list of standard options .de SE .fi .ft R .LP See the \\fBoptions\\fR manual entry for details on the standard options. .. '\" # OP - start of full description for a single option .de OP .LP .nf .ta 4c Command-Line Name: \\fB\\$1\\fR Database Name: \\fB\\$2\\fR Database Class: \\fB\\$3\\fR .fi .IP .. '\" # CS - begin code excerpt .de CS .RS .nf .ta .25i .5i .75i 1i .. '\" # CE - end code excerpt .de CE .fi .RE .. .de UL \\$1\l'|0\(ul'\\$2 .. .TH tclvars n 7.5 Tcl "Tcl Built-In Commands" .BS '\" Note: do not modify the .SH NAME line immediately below! .SH NAME tclvars \- Variables used by Tcl .BE .SH DESCRIPTION .PP The following global variables are created and managed automatically by the Tcl library. Except where noted below, these variables should normally be treated as read-only by application-specific code and by users. .TP \fBenv\fR This variable is maintained by Tcl as an array whose elements are the environment variables for the process. Reading an element will return the value of the corresponding environment variable. Setting an element of the array will modify the corresponding environment variable or create a new one if it doesn't already exist. Unsetting an element of \fBenv\fR will remove the corresponding environment variable. Changes to the \fBenv\fR array will affect the environment passed to children by commands like \fBexec\fR. If the entire \fBenv\fR array is unset then Tcl will stop monitoring \fBenv\fR accesses and will not update environment variables. .TP \fBerrorCode\fR After an error has occurred, this variable will be set to hold additional information about the error in a form that is easy to process with programs. \fBerrorCode\fR consists of a Tcl list with one or more elements. The first element of the list identifies a general class of errors, and determines the format of the rest of the list. The following formats for \fBerrorCode\fR are used by the Tcl core; individual applications may define additional formats. .RS .TP \fBARITH\fI code msg\fR .VS This format is used when an arithmetic error occurs (e.g. an attempt to divide by zero in the \fBexpr\fR command). \fICode\fR identifies the precise error and \fImsg\fR provides a human-readable description of the error. \fICode\fR will be either DIVZERO (for an attempt to divide by zero), DOMAIN (if an argument is outside the domain of a function, such as acos(\-3)), IOVERFLOW (for integer overflow), OVERFLOW (for a floating-point overflow), or UNKNOWN (if the cause of the error cannot be determined). .VE .TP \fBCHILDKILLED\fI pid sigName msg\fR This format is used when a child process has been killed because of a signal. The second element of \fBerrorCode\fR will be the process's identifier (in decimal). The third element will be the symbolic name of the signal that caused the process to terminate; it will be one of the names from the include file signal.h, such as \fBSIGPIPE\fR. The fourth element will be a short human-readable message describing the signal, such as ``write on pipe with no readers'' for \fBSIGPIPE\fR. .TP \fBCHILDSTATUS\fI pid code\fR This format is used when a child process has exited with a non-zero exit status. The second element of \fBerrorCode\fR will be the process's identifier (in decimal) and the third element will be the exit code returned by the process (also in decimal). .TP \fBCHILDSUSP\fI pid sigName msg\fR This format is used when a child process has been suspended because of a signal. The second element of \fBerrorCode\fR will be the process's identifier, in decimal. The third element will be the symbolic name of the signal that caused the process to suspend; this will be one of the names from the include file signal.h, such as \fBSIGTTIN\fR. The fourth element will be a short human-readable message describing the signal, such as ``background tty read'' for \fBSIGTTIN\fR. .TP \fBNONE\fR This format is used for errors where no additional information is available for an error besides the message returned with the error. In these cases \fBerrorCode\fR will consist of a list containing a single element whose contents are \fBNONE\fR. .TP \fBPOSIX \fIerrName msg\fR .VS If the first element of \fBerrorCode\fR is \fBPOSIX\fR, then the error occurred during a POSIX kernel call. .VE The second element of the list will contain the symbolic name of the error that occurred, such as \fBENOENT\fR; this will be one of the values defined in the include file errno.h. The third element of the list will be a human-readable message corresponding to \fIerrName\fR, such as ``no such file or directory'' for the \fBENOENT\fR case. .PP To set \fBerrorCode\fR, applications should use library procedures such as \fBTcl_SetErrorCode\fR and .VS \fBTcl_PosixError\fR, .VE or they may invoke the \fBerror\fR command. If one of these methods hasn't been used, then the Tcl interpreter will reset the variable to \fBNONE\fR after the next error. .RE .TP \fBerrorInfo\fR After an error has occurred, this string will contain one or more lines identifying the Tcl commands and procedures that were being executed when the most recent error occurred. Its contents take the form of a stack trace showing the various nested Tcl commands that had been invoked at the time of the error. .TP \fBtcl_library\fR .VS This variable holds the network name of a directory containing the system library of Tcl scripts, such as those used for auto-loading. The value of this variable is returned by the \fBinfo library\fR command. See the \fBlibrary\fR manual entry for details of the facilities rovided by the Tcl script library. Normally each application or package will have its own application-specific script library in addition to the Tcl script library; each application should set a global variable with a name like \fB$\fIapp\fB_library\fR (where \fIapp\fR is the application's name) to hold the network file name for that application's library directory. The initial value of \fBtcl_library\fR is set when an interpreter is created by searching several different directories until one is found that contains an appropriate Tcl startup script. If the \fBTCL_LIBRARY\fR environment variable exists, then the directory it names is checked first. If \fBTCL_LIBRARY\fR isn't set or doesn't refer to an appropriate directory, then Tcl checks several other directories based on a compiled-in default location, the location of the binary containing the application, and the current working directory. .VE .TP \fBtcl_patchLevel\fR When an interpreter is created Tcl initializes this variable to hold a string giving the current patch level for Tcl, such as \fB7.3p2\fR for Tcl 7.3 with the first two official patches, or \fB7.4b4\fR for the fourth beta release of Tcl 7.4. The value of this variable is returned by the \fBinfo patchlevel\fR command. .VS br .TP \fBtcl_platform\fR This is an associative array whose elements contain information about the platform on which the application is running, such as the name of the operating system, its current release number, and the machine's instruction set. The elements listed below will always be defined, but they may have empty strings as values if Tcl couldn't retrieve any relevant information. In addition, extensions and applications may add additional values to the array. The predefined elements are: .RS .TP \fBmachine\fR The instruction set executed by this machine, such as \fBPPC\fR, \fB68k\fR, or \fBsun4m\fR. On UNIX machines, this is the value returned by \fBuname -m\fR. .TP \fBos\fR The name of the operating system running on this machine, such as \fBWin95\fR, \fBMacOS\fR, or \fBSunOS\fR. On UNIX machines, this is the value returned by \fBuname -s\fR. .TP \fBosVersion\fR The version number for the operating system running on this machine. On UNIX machines, this is the value returned by \fBuname -r\fR. .TP \fBplatform\fR Either \fBwindows\fR, \fBmacintosh\fR, or \fBunix\fR. This identifies the general operating environment of the machine. .RE .VE .TP \fBtcl_precision\fR If this variable is set, it must contain a decimal number giving the number of significant digits to include when converting floating-point values to strings. If this variable is not set then 6 digits are included. 17 digits is ``perfect'' for IEEE floating-point in that it allows double-precision values to be converted to strings and back to binary with no loss of precision. .VS br .TP \fBtcl_rcFileName\fR This variable is used during initialization to indicate the name of a user-specific startup file. If it is set by application-specific initialization, then the Tcl startup code will check for the existence of this file and \fBsource\fR it if it exists. For example, for \fBwish\fR the variable is set to \fB~/.wishrc\fR. .VE .TP \fBtcl_version\fR When an interpreter is created Tcl initializes this variable to hold the version number for this version of Tcl in the form \fIx.y\fR. Changes to \fIx\fR represent major changes with probable incompatibilities and changes to \fIy\fR represent small enhancements and bug fixes that retain backward compatibility. The value of this variable is returned by the \fBinfo tclversion\fR command. .SH KEYWORDS arithmetic, error, environment, POSIX, precision, subprocess, variables