§19   字符串子命令 - length index range

实例：

# cat ch19

# !/bin/bash

# \

exec tclsh "$0" "$@"

set string "this is my test string"

puts "There are [string length $string] characters in \"$string\""

puts "[string index $string 1] is the second character in \"$string\""

puts "\"[string range $string 5 10]\" are characters between the 5'th and 10'th"

运行结果：

# ./ch19

There are 22 characters in "this is my test string"

h is the second character in "this is my test string"

"is my " are characters between the 5'th and 10'th