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.
