info(3tcl)


NAME

   info - Return information about the state of the Tcl interpreter

SYNOPSIS

   info option ?arg arg ...?
______________________________________________________________________________

DESCRIPTION

   This  command  provides  information about various internals of the Tcl
   interpreter.  The legal options (which may be abbreviated) are:

   info args procname
          Returns  a  list  containing  the  names  of  the  arguments  to
          procedure  procname,  in  order.  Procname must be the name of a
          Tcl command procedure.

   info body procname
          Returns the body of procedure procname.  Procname  must  be  the
          name of a Tcl command procedure.

   info cmdcount
          Returns  a  count of the total number of commands that have been
          invoked in this interpreter.

   info commands ?pattern?
          If pattern is not specified, returns a list of names of all  the 
          Tcl  commands visible (i.e. executable without using a qualified 
          name) to the current  namespace,  including  both  the  built-in 
          commands  written  in C and the command procedures defined using 
          the proc command.  If pattern is  specified,  only  those  names 
          matching pattern are returned.  Matching is determined using the 
          same rules as for string match.  pattern can be a qualified name 
          like   Foo::print*.   That  is,  it  may  specify  a  particular 
          namespace using a  sequence  of  namespace  names  separated  by 
          double  colons  (::),  and  may  have  pattern  matching special 
          characters at the end to specify  a  set  of  commands  in  that 
          namespace.   If  pattern is a qualified name, the resulting list 
          of command names has each one qualified with  the  name  of  the 
          specified  namespace, and only the commands defined in the named 
          namespace are returned.

   info complete command
          Returns 1 if command is a complete Tcl command in the  sense  of
          having  no  unclosed  quotes,  braces, brackets or array element
          names.  If the command does not appear to be complete then 0  is
          returned.  This command is typically used in line-oriented input
          environments to allow  users  to  type  in  commands  that  span
          multiple  lines;  if the command is not complete, the script can
          delay evaluating it until additional lines have  been  typed  to
          complete the command.

   info default procname arg varname
          Procname  must  be  the  name of a Tcl command procedure and arg
          must be the name of an argument to that procedure.  If arg  does
          not  have a default value then the command returns 0.  Otherwise
          it returns 1 and places the default value of arg  into  variable
          varname.

   info exists varName
          Returns  1  if  the variable named varName exists in the current
          context (either as a global or  local  variable)  and  has  been
          defined by being given a value, returns 0 otherwise.

   info frame ?number?
          This  command  provides  access to all frames on the stack, even
          those hidden from info level. If number is not  specified,  this
          command  returns a number giving the frame level of the command.
          This is 1 if the command is invoked at top-level. If  number  is
          specified,  then  the  result  is  a  dictionary  containing the
          location information for the command at the  numbered  level  on
          the stack.

          If  number  is positive (> 0) then it selects a particular stack
          level (1 refers to the top-most active command, i.e., info frame
          itself,  2  to  the  command  it  was  called  from, and so on);
          otherwise it gives a level relative to the  current  command  (0
          refers  to  the  current command, i.e., info frame itself, -1 to
          its caller, and so on).

          This is similar to  how  info  level  works,  except  that  this
          subcommand  reports  all  frames,  like  sourced scripts, evals,
          uplevels, etc.

          Note that for nested commands, like "foo [bar  [x]]",  only  "x"
          will  be  seen by an info frame invoked within "x".  This is the
          same as for info level and error stack traces.

          The result dictionary may contain the keys  listed  below,  with
          the specified meanings for their values:

          type   This  entry is always present and describes the nature of
                 the location for the command. The recognized  values  are
                 source, proc, eval, and precompiled.

                 source
                        means that the command is found in a script loaded
                        by the source command.

                 proc
                        means that the command  is  found  in  dynamically
                        created procedure body.

                 eval
                        means  that  the  command  is  executed by eval or
                        uplevel.

                 precompiled
                        means that the command is found in  a  precompiled
                        script  (loadable  by the package tbcload), and no
                        further information will be available.

          line   This entry provides the number of the line the command is
                 at inside of the script it is a part of. This information
                 is not present for type precompiled. For type source this
                 information  is  counted relative to the beginning of the
                 file, whereas for the last two types the line is  counted
                 relative to the start of the script.

          file   This  entry  is present only for type source. It provides
                 the normalized path of the file the command is in.

          cmd    This entry provides  the  string  representation  of  the
                 command.  This is usually the unsubstituted form, however
                 for commands which are a pure list executed by eval it is
                 the  substituted  form  as  they  have  no  other  string
                 representation. Care is taken that the pure-List property
                 of the latter is not spoiled.

          proc   This entry is present only if the command is found in the
                 body of a regular Tcl procedure.  It  then  provides  the
                 name of that procedure.

          lambda This entry is present only if the command is found in the
                 body of an anonymous Tcl procedure,  i.e.  a  lambda.  It
                 then  provides  the  entire  definition  of the lambda in
                 question.

          level  This entry is present only if the  queried  frame  has  a
                 corresponding  frame  returned by info level. It provides
                 the index of this frame, relative to the current level (0
                 and negative numbers).

          A  thing  of  note  is that for procedures statically defined in
          files the locations of commands in their bodies will be reported
          with  type  source  and  absolute  line numbers, and not as type
          proc. The same is  true  for  procedures  nested  in  statically
          defined  procedures,  and  literal  eval  scripts  in  files  or
          statically defined procedures.

          In contrast, a procedure definition or eval within a dynamically
          evaluated environment count linenumbers relative to the start of
          their script, even if they would be able to  count  relative  to
          the  start  of  the  outer  dynamic  script. That type of number
          usually makes more sense.

          A different way of describing this behaviour is that file  based
          locations  are  tracked as deeply as possible, and where this is
          not possible  the  lines  are  counted  based  on  the  smallest
          possible eval or procedure body, as that scope is usually easier
          to find than any dynamic outer scope.

          The syntactic form {*} is handled like eval. I.e. if it is given
          a  literal list argument the system tracks the linenumber within
          the list words  as  well,  and  otherwise  all  linenumbers  are
          counted relative to the start of each word (smallest scope)

   info functions ?pattern?
          If  pattern  is  not  specified,  returns a list of all the math
          functions currently defined.   If  pattern  is  specified,  only
          those   functions  whose  name  matches  pattern  are  returned.
          Matching is determined using the same rules as for string match.

   info globals ?pattern?
          If pattern is not specified, returns a list of all the names  of
          currently-defined   global   variables.   Global  variables  are
          variables in the global namespace.   If  pattern  is  specified,
          only  those  names  matching  pattern are returned.  Matching is
          determined using the same rules as for string match.

   info hostname
          Returns the name of the computer on  which  this  invocation  is
          being executed.  Note that this name is not guaranteed to be the
          fully qualified domain name of the host.   Where  machines  have
          several  different  names  (as  is  common  on systems with both
          TCP/IP (DNS) and NetBIOS-based networking installed,) it is  the
          name that is suitable for TCP/IP networking that is returned.

   info level ?number?
          If number is not specified, this command returns a number giving
          the stack level of the invoking procedure, or 0 if  the  command
          is  invoked  at  top-level.   If  number  is specified, then the
          result is a list consisting of the name and  arguments  for  the
          procedure  call  at  level  number  on  the stack.  If number is
          positive then it selects a particular stack level (1  refers  to
          the top-most active procedure, 2 to the procedure it called, and
          so on); otherwise it gives a level relative to the current level
          (0  refers  to  the  current procedure, -1 to its caller, and so
          on).  See the uplevel command for more information on what stack
          levels mean.

   info library
          Returns  the name of the library directory in which standard Tcl
          scripts  are  stored.   This  is  actually  the  value  of   the
          tcl_library  variable and may be changed by setting tcl_library.
          See the tclvars manual entry for more information.

   info loaded ?interp?
          Returns a list describing all of the  packages  that  have  been
          loaded  into interp with the load command.  Each list element is
          a sub-list with two elements consisting of the name of the  file
          from  which  the package was loaded and the name of the package.
          For statically-loaded packages the file name will  be  an  empty
          string.   If  interp is omitted then information is returned for
          all packages loaded in any interpreter in the process.  To get a
          list of just the packages in the current interpreter, specify an
          empty string for the interp argument.

   info locals ?pattern?
          If pattern is not specified, returns a list of all the names  of
          currently-defined  local  variables,  including arguments to the
          current procedure, if any.  Variables defined with  the  global,
          upvar   and  variable commands will not be returned.  If pattern
          is specified, only those names matching  pattern  are  returned.
          Matching is determined using the same rules as for string match.

   info nameofexecutable
          Returns  the  full  path  name of the binary file from which the
          application was invoked.  If Tcl  was  unable  to  identify  the
          file, then an empty string is returned.

   info patchlevel
          Returns the value of the global variable tcl_patchLevel; see the
          tclvars manual entry for more information.

   info procs ?pattern?
          If pattern is not specified, returns a list of all the names  of
          Tcl  command procedures in the current namespace.  If pattern is
          specified, only those procedure names in the  current  namespace
          matching pattern are returned.  Matching is determined using the
          same rules  as  for  string  match.   If  pattern  contains  any
          namespace  separators,  they  are  used  to  select  a namespace
          relative to the current namespace (or  relative  to  the  global
          namespace  if  pattern  starts  with  ::)  to  match within; the
          matching pattern  is  taken  to  be  the  part  after  the  last
          namespace separator.

   info script ?filename?
          If a Tcl script file is currently being evaluated (i.e. there is
          a call to Tcl_EvalFile active or there is an  active  invocation
          of  the  source  command), then this command returns the name of
          the innermost file being processed.  If filename  is  specified,
          then  the  return value of this command will be modified for the
          duration of the active invocation to return that name.  This  is
          useful  in  virtual  file  system  applications.   Otherwise the
          command returns an empty string.

   info sharedlibextension
          Returns the extension used on this platform  for  the  names  of
          files  containing  shared  libraries  (for  example,  .so  under
          Solaris).   If  shared  libraries  are  not  supported  on  this
          platform then an empty string is returned.

   info tclversion
          Returns  the  value  of the global variable tcl_version; see the
          tclvars manual entry for more information.

   info vars ?pattern?
          If pattern is not specified, returns a list of all the names  of
          currently-visible   variables.    This   includes   locals   and
          currently-visible globals.  If pattern is specified, only  those
          names  matching  pattern  are  returned.  Matching is determined
          using the same rules as for string  match.   pattern  can  be  a
          qualified  name  like  Foo::option*.   That is, it may specify a
          particular  namespace  using  a  sequence  of  namespace   names
          separated  by  double colons (::), and may have pattern matching
          special characters at the end to specify a set of  variables  in
          that  namespace.   If pattern is a qualified name, the resulting
          list of variable names  has  each  matching  namespace  variable
          qualified   with  the  name  of  its  namespace.   Note  that  a
          currently-visible variable may not yet "exist"  if  it  has  not
          been set (e.g. a variable declared but not set by variable).

EXAMPLE

   This  command  prints  out  a  procedure  suitable  for saving in a Tcl
   script:

          proc printProc {procName} {
              set result [list proc $procName]
              set formals {}
              foreach var [info args $procName] {
                  if {[info default $procName $var def]} {
                      lappend formals [list $var $def]
                  } else {
                      # Still need the list-quoting because variable
                      # names may properly contain spaces.
                      lappend formals [list $var]
                  }
              }
              puts [lappend result $formals [info body $procName]]
          }

SEE ALSO

   global(3tcl), proc(3tcl)

KEYWORDS

   command,  information,  interpreter,   level,   namespace,   procedure,
   variable





Opportunity


Personal Opportunity - Free software gives you access to billions of dollars of software at no cost. Use this software for your business, personal use or to develop a profitable skill. Access to source code provides access to a level of capabilities/information that companies protect though copyrights. Open source is a core component of the Internet and it is available to you. Leverage the billions of dollars in resources and capabilities to build a career, establish a business or change the world. The potential is endless for those who understand the opportunity.

Business Opportunity - Goldman Sachs, IBM and countless large corporations are leveraging open source to reduce costs, develop products and increase their bottom lines. Learn what these companies know about open source and how open source can give you the advantage.





Free Software


Free Software provides computer programs and capabilities at no cost but more importantly, it provides the freedom to run, edit, contribute to, and share the software. The importance of free software is a matter of access, not price. Software at no cost is a benefit but ownership rights to the software and source code is far more significant.


Free Office Software - The Libre Office suite provides top desktop productivity tools for free. This includes, a word processor, spreadsheet, presentation engine, drawing and flowcharting, database and math applications. Libre Office is available for Linux or Windows.





Free Books


The Free Books Library is a collection of thousands of the most popular public domain books in an online readable format. The collection includes great classical literature and more recent works where the U.S. copyright has expired. These books are yours to read and use without restrictions.


Source Code - Want to change a program or know how it works? Open Source provides the source code for its programs so that anyone can use, modify or learn how to write those programs themselves. Visit the GNU source code repositories to download the source.





Education


Study at Harvard, Stanford or MIT - Open edX provides free online courses from Harvard, MIT, Columbia, UC Berkeley and other top Universities. Hundreds of courses for almost all major subjects and course levels. Open edx also offers some paid courses and selected certifications.


Linux Manual Pages - A man or manual page is a form of software documentation found on Linux/Unix operating systems. Topics covered include computer programs (including library and system calls), formal standards and conventions, and even abstract concepts.