Home Man
Search
Today's Posts
Register

Linux & Unix Commands - Search Man Pages

OpenDarwin 7.2.1 - man page for tclvars (opendarwin section n)

tclvars(n)			      Tcl Built-In Commands			       tclvars(n)

_________________________________________________________________________________________________

NAME
       tclvars - Variables used by Tcl
_________________________________________________________________

DESCRIPTION
       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.

       env    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  corre-
	      sponding	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  env will remove the corresponding environment variable.
	      Changes to the env array will affect the environment passed to children by commands
	      like  exec.   If	the  entire  env array is unset then Tcl will stop monitoring env
	      accesses and will not update environment variables.
	      Under Windows, the environment variables PATH and COMSPEC in any capitalization are |
	      converted  automatically	to  upper case.  For instance, the PATH variable could be |
	      exported by the operating system as ``path'',  ``Path'',	``PaTh'',  etc.,  causing |
	      otherwise  simple  Tcl code to have to support many special cases.  All other envi- |
	      ronment variables inherited by Tcl are left unmodified.  Setting an env array vari- |
	      able to blank is the same as unsetting it as this is the behavior of the underlying |
	      Windows OS.  It should be noted that relying on an existing and  empty  environment |
	      variable won't work on windows and is discouraged for cross-platform usage.
	      On the Macintosh, the environment variable is constructed by Tcl as no global envi-
	      ronment variable exists.	The  environment  variables  that  are	created  for  Tcl
	      include:

	      LOGIN  This holds the Chooser name of the Macintosh.

	      USER   This also holds the Chooser name of the Macintosh.

	      SYS_FOLDER
		     The path to the system directory.

	      APPLE_M_FOLDER
		     The path to the Apple Menu directory.

	      CP_FOLDER
		     The path to the control panels directory.

	      DESK_FOLDER
		     The path to the desk top directory.

	      EXT_FOLDER
		     The path to the system extensions directory.

	      PREF_FOLDER
		     The path to the preferences directory.

	      PRINT_MON_FOLDER
		     The path to the print monitor directory.

	      SHARED_TRASH_FOLDER
		     The path to the network trash directory.

	      TRASH_FOLDER
		     The path to the trash directory.

	      START_UP_FOLDER
		     The path to the start up directory.

	      HOME   The path to the application's default directory.

	      You can also create your own environment variables for the Macintosh.  A file named
	      Tcl Environment Variables may be placed in the preferences folder in the Mac system
	      folder.  Each line of this file should be of the form VAR_NAME=var_data.

	      The  last  alternative is to place environment variables in a 'STR#' resource named
	      Tcl Environment Variables of the application.  This is  considered  a  little  more
	      ``Mac like'' than a Unix style Environment Variable file.  Each entry in the 'STR#'
	      resource has the same format as above.  The source code file  tclMacEnv.c  contains
	      the  implementation  of the env mechanisms.  This file contains many #define's that
	      allow customization of the env mechanisms to fit your applications needs.

       errorCode
	      After an error has occurred, this variable will be set to hold additional  informa-
	      tion  about  the	error in a form that is easy to process with programs.	errorCode
	      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 errorCode are used by  the  Tcl	core;  individual
	      applications may define additional formats.

	      ARITH code msg
		     This  format  is  used  when  an arithmetic error occurs (e.g. an attempt to
		     divide by zero in the expr command).  Code identifies the precise error  and
		     msg provides a human-readable description of the error.  Code will be either
		     DIVZERO (for an attempt to divide by zero), DOMAIN (if an argument  is  out-
		     side  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).

	      CHILDKILLED pid sigName msg
		     This  format  is used when a child process has been killed because of a sig-
		     nal.  The second element of errorCode 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 SIGPIPE.  The fourth element will be a short
		     human-readable message describing the signal, such as ``write on  pipe  with
		     no readers'' for SIGPIPE.

	      CHILDSTATUS pid code
		     This  format  is  used  when a child process has exited with a non-zero exit
		     status.  The second element of errorCode will be  the  process's  identifier
		     (in  decimal)  and  the  third element will be the exit code returned by the
		     process (also in decimal).

	      CHILDSUSP pid sigName msg
		     This format is used when a child process has been	suspended  because  of	a
		     signal.   The  second element of errorCode 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 SIGTTIN.  The fourth element will be a  short
		     human-readable  message  describing  the  signal,	such  as ``background tty
		     read'' for SIGTTIN.

	      NONE   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
		     errorCode will consist of a list containing a single element whose  contents
		     are NONE.

	      POSIX errName msg
		     If the first element of errorCode is POSIX, then the error occurred during a
		     POSIX kernel call.  The second element of the list will contain the symbolic
		     name  of  the  error  that occurred, such as ENOENT; 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 errName, such as ``no such
		     file or directory'' for the ENOENT case.

	      To set errorCode, applications should use library procedures such as  Tcl_SetError-
	      Code  and  Tcl_PosixError,  or  they may invoke the error command.  If one of these
	      methods hasn't been used, then the Tcl interpreter will reset the variable to  NONE
	      after the next error.

       errorInfo
	      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.

       tcl_library
	      This variable holds the 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 info library command.  See the library manual entry for details  of
	      the  facilities  provided  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
	      $app_library (where app is the application's name) to hold the  network  file  name
	      for  that application's library directory.  The initial value of tcl_library 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 TCL_LIBRARY envi-
	      ronment variable exists,	then  the  directory  it  names  is  checked  first.   If
	      TCL_LIBRARY 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.

       tcl_patchLevel
	      When  an interpreter is created Tcl initializes this variable to hold a string giv-
	      ing the current patch level for Tcl, such as 7.3p2 for Tcl 7.3 with the  first  two
	      official	patches,  or  7.4b4 for the fourth beta release of Tcl 7.4.  The value of
	      this variable is returned by the info patchlevel command.

       tcl_pkgPath										  |
	      This variable holds a list of directories indicating where  packages  are  normally |
	      installed.   It  is  not	used on Windows.  It typically contains either one or two |
	      entries; if it contains two entries, the first is normally a  directory  for  plat- |
	      form-dependent  packages (e.g., shared library binaries) and the second is normally |
	      a directory for platform-independent packages (e.g.,  script  files).  Typically	a |
	      package  is  installed as a subdirectory of one of the entries in $tcl_pkgPath. The |
	      directories in $tcl_pkgPath are included by default in the auto_path  variable,  so |
	      they  and  their	immediate  subdirectories are automatically searched for packages |
	      during package require commands.	Note: tcl_pkgPath it not intended to be  modified |
	      by  the  application.   Its  value  is  added  to  auto_path at startup; changes to |
	      tcl_pkgPath are not reflected in auto_path.  If you want Tcl to  search  additional |
	      directories  for	packages  you  should  add  the  names	of  those  directories to |
	      auto_path, not tcl_pkgPath.

       tcl_platform
	      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  applica-
	      tions may add additional values to the array.  The predefined elements are:

	      byteOrder 									  |
		     The native byte order of this machine: either littleEndian or bigEndian.

	      debug  If  this  variable  exists, then the interpreter was compiled with debugging
		     symbols enabled.  This variable will only	exist  on  Windows  so	extension
		     writers  can  specify  which  package  to	load  depending on the C run-time
		     library that is loaded.

	      machine
		     The instruction set executed by this machine, such as intel,  PPC,  68k,  or
		     sun4m.  On UNIX machines, this is the value returned by uname -m.

	      os     The  name	of  the operating system running on this machine, such as Windows
		     95, Windows NT, MacOS, or SunOS.	On  UNIX  machines,  this  is  the  value
		     returned by uname -s.  On Windows 95 and Windows 98, the value returned will
		     be Windows 95 to provide better backwards compatibility to  Windows  95;  to
		     distinguish between the two, check the osVersion.

	      osVersion
		     The  version  number  for	the operating system running on this machine.  On
		     UNIX machines, this is the value returned by uname -r.  On Windows  95,  the
		     version will be 4.0; on Windows 98, the version will be 4.10.

	      platform
		     Either  windows,  macintosh, or unix.  This identifies the general operating
		     environment of the machine.

	      threaded
		     If this variable exists, then the	interpreter  was  compiled  with  threads
		     enabled.

	      user   This identifies the current user based on the login information available on
		     the platform.  This comes from the USER or LOGNAME environment  variable  on
		     Unix, and the value from GetUserName on Windows and Macintosh.

	      wordSize
		     This  gives  the  size  of the native-machine word in bytes (strictly, it is |
		     same as the result of evaluating sizeof(long) in C.)

       tcl_precision
	      This variable controls the number of digits to generate when  converting	floating- |
	      point  values  to  strings.   It defaults to 12.	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 information.	However, using 17 digits prevents |
	      any rounding, which produces longer, less intuitive results.  For example, expr 1.4 |
	      returns  1.3999999999999999  with tcl_precision set to 17, vs. 1.4 if tcl_precision |
	      is 12.										  |
	      All interpreters in a process share a single tcl_precision value:  changing  it  in |
	      one  interpreter	will affect all other interpreters as well.  However, safe inter- |
	      preters are not allowed to modify the variable.					  |

       tcl_rcFileName
	      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 source it if it  exists.
	      For  example,  for  wish the variable is set to ~/.wishrc for Unix and ~/wishrc.tcl
	      for Windows.

       tcl_rcRsrcName
	      This variable is only used on Macintosh systems.	The variable is used during  ini-
	      tialization  to  indicate  the name of a user-specific TEXT resource located in the
	      application or extension resource forks.	If it is set by application-specific ini-
	      tialization,  then  the  Tcl  startup  code  will  check	for the existence of this
	      resource and source it if it exists.  For example, the Macintosh	wish  application
	      has the variable is set to tclshrc.

       tcl_traceCompile
	      The  value  of  this variable can be set to control how much tracing information is
	      displayed during bytecode compilation.  By default, tcl_traceCompile is zero and no
	      information  is displayed.  Setting tcl_traceCompile to 1 generates a one line sum-
	      mary in stdout whenever a procedure or top level command is compiled.   Setting  it
	      to  2  generates	a detailed listing in stdout of the bytecode instructions emitted
	      during every compilation.  This variable is useful in tracking down suspected prob-
	      lems  with the Tcl compiler.  It is also occasionally useful when converting exist-
	      ing code to use Tcl8.0.

	      This variable and functionality only exist if TCL_COMPILE_DEBUG was defined  during
	      Tcl's compilation.

       tcl_traceExec
	      The  value  of  this variable can be set to control how much tracing information is
	      displayed during bytecode execution.  By default,  tcl_traceExec	is  zero  and  no
	      information is displayed.  Setting tcl_traceExec to 1 generates a one line trace in
	      stdout on each call to a Tcl procedure.  Setting it to 2 generates a line of output
	      whenever	any  Tcl command is invoked that contains the name of the command and its
	      arguments.  Setting it to 3 produces a detailed trace showing the result of execut-
	      ing  each  bytecode  instruction.  Note that when tcl_traceExec is 2 or 3, commands
	      such as set and incr that have been entirely replaced by	a  sequence  of  bytecode
	      instructions  are not shown.  Setting this variable is useful in tracking down sus-
	      pected problems with the bytecode compiler and interpreter.  It is  also	occasion-
	      ally useful when converting code to use Tcl8.0.

	      This  variable and functionality only exist if TCL_COMPILE_DEBUG was defined during
	      Tcl's compilation.

       tcl_wordchars
	      The value of this variable is a regular expression that can be set to control  what
	      are  considered ``word'' characters, for instances like selecting a word by double-
	      clicking in text in Tk.  It is platform dependent.  On Windows, it defaults to  \S,
	      meaning anything but a Unicode space character.  Otherwise it defaults to \w, which
	      is any Unicode word character (number, letter, or underscore).

       tcl_nonwordchars
	      The value of this variable is a regular expression that can be set to control  what
	      are considered ``non-word'' characters, for instances like selecting a word by dou-
	      ble-clicking in text in Tk.  It is platform dependent.  On Windows, it defaults  to
	      \s,  meaning  any  Unicode  space character.  Otherwise it defaults to \W, which is
	      anything but a Unicode word character (number, letter, or underscore).

       tcl_version
	      When an interpreter is created Tcl initializes this variable to  hold  the  version
	      number  for  this  version  of  Tcl  in the form x.y.  Changes to x represent major
	      changes with probable incompatibilities and changes to y represent  small  enhance-
	      ments and bug fixes that retain backward compatibility.  The value of this variable
	      is returned by the info tclversion command.

SEE ALSO
       eval(n)

KEYWORDS
       arithmetic, bytecode, compiler, error, environment, POSIX,  precision,  subprocess,  vari-
       ables

Tcl					       8.0				       tclvars(n)


All times are GMT -4. The time now is 02:22 PM.

Unix & Linux Forums Content Copyrightę1993-2018. All Rights Reserved.
UNIX.COM Login
Username:
Password:  
Show Password