实战Tcl和TK程序设计 第2章 开始使用

§2    开始使用

本章主要在不同的操作系统平台上运行Tcl与Tk,涉及的命令有: Source,console,info.

Wish即: windowing shell.

可以用在tcl的命令行使用source filename 导入文件.

      

 

#!/bin/sh

# Run wish from the users PATH \

exec wish -f "$0" ${1+"$@"}

优点:

1,二进制文件的位置不需要填入,它可以在你的 shell 查找路径中的任何地方。

2,突破了#!只有30个字符的限制

3,在shell中, 第2行是注释,第3行不是.但是在tcl中, \是连接符号,下一行依旧是注释.所以只有shell有机会执行第3行.exec 语句导致 shell 停止处理而启动 tclsh 来重新处理整个脚本。当 tclsh启动时，因为第二行的反斜线导致第三行被作为第二行注释的一部分，它把所有三行都作为注释对待。

${1+"$@"}

${1+"$@"}  的意思是判断$1是否设置过也就是定义过如果设置就设"$@"
而${1:+"$@"} 是判断是否空串如果不是空串那就设置"$@"

          Some shells expand "$@" like "" (a single empty argument) when there

are no arguments.  ${1+"$@"} correctly expands to no arguments on

those shells.

Example 2-4 The EchoArgs script

# Tcl script to echo command line arguments

puts "Program: $argv0"

puts "Number of arguments: $argc"

set i 0

foreach arg $argv {

   puts "Arg $i: $arg"

   incr i

}

Table 2-1. Wish command line options
-colormap new	Use a new private colormap. See page 624.
-display display	Use the specified X display. UNIX only.
-geometry geometry	The size and position of the window. See page 658.
-name name	Specify the Tk application name. See page 648.
-sync	Run X synchronously. UNIX only.
-use id	Use the window specified by id for the main window. See page 667.
-visual visual	Specify the visual for the main window. See page 624.
--	Terminate options to wish.

Table 2-2. Variables defined by tclsh and wish
argc	The number of command-line arguments.
argv	A list of the command-line arguments.
argv0	The name of the script being executed. If being used interactively, argv0 is the name of the shell program.
embed_args	The list of arguments in the tag. Tcl applets only. See page 314.
env	An array of the environment variables. See page 124.
tcl_interactive	True (one) if the tclsh is prompting for commands.
tcl_library	The script library directory.
tcl_patchLevel	Modified version number, e.g., 8.0b1.
tcl_platform	Array containing operating system information. See page 192.
tcl_prompt1	If defined, this is a command that outputs the prompt.
tcl_prompt2	If defined, this is a command that outputs the prompt if the current command is not yet complete.
tcl_version	Version number.
auto_path	The search path for script library directories. See page 172.
auto_index	A map from command name to a Tcl command that defines it.
auto_noload	If set, the library facility is disabled.
auto_noexec	If set, the auto execute facility is disabled.
geometry	(wish only). The value of the -geometry argument.