Tcl Applications tclsh(1)
NAME
tclsh - Simple shell containing Tcl interpreter
SYNOPSIS
tclsh ?fileName arg arg ...?
DESCRIPTION
Tclsh is a shell-like application that reads Tcl commands
from its standard input or from a file and evaluates them.
If invoked with no arguments then it runs interactively,
reading Tcl commands from standard input and printing com-
mand results and error messages to standard output. It runs
until the exit command is invoked or until it reaches end-
of-file on its standard input. If there exists a file
.tclshrc (or tclshrc.tcl on the Windows platforms) in the
home directory of the user, tclsh evaluates the file as a
Tcl script just before reading the first command from stan-
dard input.
SCRIPT FILES
If tclsh is invoked with arguments then the first argument
is the name of a script file and any additional arguments
are made available to the script as variables (see below).
Instead of reading commands from standard input tclsh will
read Tcl commands from the named file; tclsh will exit when
it reaches the end of the file. The end of the file may be
marked either by the physical end of the medium, or by the
character, '\032' ('\u001a', control-Z). If this character
is present in the file, the tclsh application will read text
up to but not including the character. An application that
requires this character in the file may safely encode it as
``\032'', ``\x1a'', or ``\u001a''; or may generate it by use
of commands such as format or binary. There is no automatic
evaluation of .tclshrc when the name of a script file is
presented on the tclsh command line, but the script file can
always source it if desired.
If you create a Tcl script in a file whose first line is
#!/usr/local/bin/tclsh
then you can invoke the script file directly from your shell
if you mark the file as executable. This assumes that tclsh
has been installed in the default location in
/usr/local/bin; if it's installed somewhere else then
you'll have to modify the above line to match. Many UNIX
systems do not allow the #! line to exceed about 30 charac-
ters in length, so be sure that the tclsh executable can be
accessed with a short file name.
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Tcl Applications tclsh(1)
An even better approach is to start your script files with
the following three lines:
#!/bin/sh
# the next line restarts using tclsh \
exec tclsh "$0" "$@"
This approach has three advantages over the approach in the
previous paragraph. First, the location of the tclsh binary
doesn't have to be hard-wired into the script: it can be
anywhere in your shell search path. Second, it gets around
the 30-character file name limit in the previous approach.
Third, this approach will work even if tclsh is itself a
shell script (this is done on some systems in order to han-
dle multiple architectures or operating systems: the tclsh
script selects one of several binaries to run). The three
lines cause both sh and tclsh to process the script, but the
exec is only executed by sh. sh processes the script first;
it treats the second line as a comment and executes the
third line. The exec statement cause the shell to stop pro-
cessing and instead to start up tclsh to reprocess the
entire script. When tclsh starts up, it treats all three
lines as comments, since the backslash at the end of the
second line causes the third line to be treated as part of
the comment on the second line.
You should note that it is also common practise to install
tclsh with its version number as part of the name. This has
the advantage of allowing multiple versions of Tcl to exist
on the same system at once, but also the disadvantage of
making it harder to write scripts that start up uniformly
across different versions of Tcl.
VARIABLES
Tclsh sets the following Tcl variables:
argc Contains a count of the number of arg argu-
ments (0 if none), not including the name of
the script file.
argv Contains a Tcl list whose elements are the
arg arguments, in order, or an empty string
if there are no arg arguments.
argv0 Contains fileName if it was specified. Oth-
erwise, contains the name by which tclsh was
invoked.
tclinteractive
Contains 1 if tclsh is running interactively
(no fileName was specified and standard input
is a terminal-like device), 0 otherwise.
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Tcl Applications tclsh(1)
PROMPTS
When tclsh is invoked interactively it normally prompts for
each command with ``% ''. You can change the prompt by set-
ting the variables tclprompt1 and tclprompt2. If variable
tclprompt1 exists then it must consist of a Tcl script to
output a prompt; instead of outputting a prompt tclsh will
evaluate the script in tclprompt1. The variable
tclprompt2 is used in a similar way when a newline is typed
but the current command isn't yet complete; if tclprompt2
isn't set then no prompt is output for incomplete commands.
STANDARD CHANELS
See TclStandardChannels for more explanations.
SEE ALSO
fconfigure(1T), tclvars(1T)
KEYWORDS
argument, interpreter, prompt, script file, shell
ATRIBUTES
See attributes(5) for descriptions of the following attri-
butes:
ATRIBUTE TYPE ATRIBUTE VALUE
Availability SUNWTcl
Interface Stability Uncommitted
NOTES
Source for Tcl is available on http:/opensolaris.org.
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