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Wish is a simple program consisting of the Tcl command language, the Tk toolkit, and a main program that reads commands from standard input or from a file. It creates a main window and then processes Tcl commands. If wish is invoked with no arguments, or with a first argument that starts with ‘‘-’’, then it reads Tcl commands interactively from standard input. It will continue processing commands until all windows have been deleted or until end-of-file is reached on standard input. If there exists a file .wishrc in the home directory of the user, wish evaluates the file as a Tcl script just before reading the first command from standard input.
If wish is invoked with an initial fileName argument, then fileName is treated as the name of a script file. Wish will evaluate the script in fileName (which presumably creates a user interface), then it will respond to events until all windows have been deleted. Commands will not be read from standard input. There is no automatic evaluation of .wishrc when the name of a script file is presented on the wish command line, but the script file can always source it if desired.
Wish automatically processes all of the command-line options described in the OPTIONS summary above. Any other command-line arguments besides these are passed through to the application using the argc and argv variables described later.
The name of the application, which is used for purposes such as send commands, is taken from the -name option, if it is specified; otherwise it is taken from fileName, if it is specified, or from the command name by which wish was invoked. In the last two cases, if the name contains a ‘‘/’’ character, then only the characters after the last slash are used as the application name.
The class of the application, which is used for purposes such as specifying options with a RESOURCE_MANAGER property or .Xdefaults file, is the same as its name except that the first letter is capitalized.
Wish sets the following Tcl variables:
If you create a Tcl script in a file whose first line is
#!/usr/local/bin/wishthen you can invoke the script file directly from your shell if you mark
it as executable. This assumes that wish 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 characters in length, so be sure that the wish
executable can be accessed with a short file name.
An even better approach
is to start your script files with the following three lines:
#!/bin/shThis approach has three advantages over the approach in the previous paragraph.
First, the location of the wish 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 wish is itself a shell script (this is
done on some systems in order to handle multiple architectures or operating
systems: the wish script selects one of several binaries to run). The
three lines cause both sh and wish 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 wish to reprocess
the entire script. When wish 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.
# the next line restarts using wish \
exec wish "$0" "$@"
The end of a script 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 wish application will read text up to but not including the character. An application that requires this character in the file may encode it as ‘‘\032’’, ‘‘\x1a’’, or ‘‘\u001a’’; or may generate it by use of commands such as format or binary.
When wish 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 wish will evaluate the script in tcl_prompt1. The variable tcl_prompt2 is used in a similar way when a newline is typed but the current command isn’t yet complete; if tcl_prompt2 isn’t set then no prompt is output for incomplete commands.