tclsh8.5(1) Tcl Applications tclsh8.5(1)NAMEtclsh8.5 - Simple shell containing Tcl interpreter
SYNOPSIStclsh8.5 ?-encoding name? ?fileName arg arg ...?
DESCRIPTION
Tclsh8.5 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 stan‐
dard input and printing command 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, interactive tclsh8.5 evaluates the file as a Tcl script just
before reading the first command from standard input.
SCRIPT FILES
If tclsh8.5 is invoked with arguments then the first few arguments
specify the name of a script file, and, optionally, the encoding of the
text data stored in that script file. Any additional arguments are
made available to the script as variables (see below). Instead of
reading commands from standard input tclsh8.5 will read Tcl commands
from the named file; tclsh8.5 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, If this character is present in the
file, the tclsh8.5 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 or 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 tclsh8.5 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/tclsh8.5 then you can invoke the script file directly
from your shell if you mark the file as executable. This assumes that
tclsh8.5 has been installed in the default location in /usr/local/bin;
if it is installed somewhere else then you will have to modify the
above line to match. Many UNIX systems do not allow the #! line to
exceed about 30 characters in length, so be sure that the tclsh8.5 exe‐
cutable can be accessed with a short file name.
An even better approach is to start your script files with the follow‐
ing three lines: #!/bin/sh # the next line restarts using tclsh8.5 \
exec tclsh8.5 "$0" "$@" This approach has three advantages over the
approach in the previous paragraph. First, the location of the
tclsh8.5 binary does not 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 tclsh8.5 is itself a shell script (this is
done on some systems in order to handle multiple architectures or oper‐
ating systems: the tclsh8.5 script selects one of several binaries to
run). The three lines cause both sh and tclsh8.5 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 processing and
instead to start up tclsh8.5 to reprocess the entire script. When
tclsh8.5 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 practice to install tclsh8.5
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
Tclsh8.5 sets the following Tcl variables:
argc Contains a count of the number of arg arguments (0 if
none), not including the name of the script file.
argv Contains a Tcl list whose elements are the arg argu‐
ments, in order, or an empty string if there are no arg
arguments.
argv0 Contains fileName if it was specified. Otherwise, con‐
tains the name by which tclsh8.5 was invoked.
tcl_interactive
Contains 1 if tclsh8.5 is running interactively (no
fileName was specified and standard input is a terminal-
like device), 0 otherwise.
PROMPTS
When tclsh8.5 is invoked interactively it normally prompts for each
command with You can change the prompt by setting the variables
tcl_prompt1 and tcl_prompt2. If variable tcl_prompt1 exists then it
must consist of a Tcl script to output a prompt; instead of outputting
a prompt tclsh8.5 will evaluate the script in tcl_prompt1. The vari‐
able tcl_prompt2 is used in a similar way when a newline is typed but
the current command is not yet complete; if tcl_prompt2 is not set then
no prompt is output for incomplete commands.
STANDARD CHANNELS
See Tcl_StandardChannels for more explanations.
SEE ALSOencoding(n), fconfigure(n), tclvars(n)KEYWORDS
argument, interpreter, prompt, script file, shell
Tcltclsh8.5(1)