解析 terminfo u6 字符串

Question 1

缺少一个%p标记是 ncurses 的一个怪癖：terminfo 编译器（抽动症）识别任一 terminfo （使用%p1到标记参数）或 termcap（依赖于习俗为参数）。这将是合法的术语帽表达。自从抽动症知道如何处理 termcap 表达式，显示的字符串“足够接近”，无需进一步翻译。

您可以使用以下命令查看 ncurses 的作用tput，例如，

tput u6 40 50

给出（注意参数的反转）

^[[51;41R

如果表达式给出为

u6=\E[%i%p2%d;%p1%dR

它会产生相同的结果。

u6-u9 功能是早期的扩大记录在 ncurses 的终端数据库:

# INTERPRETATION OF USER CAPABILITIES
#
# The System V Release 4 and XPG4 terminfo format defines ten string
# capabilities for use by applications, <u0>...<u9>.   In this file, we use
# certain of these capabilities to describe functions which are not covered
# by terminfo.  The mapping is as follows:
#
#       u9      terminal enquire string (equiv. to ANSI/ECMA-48 DA)
#       u8      terminal answerback description
#       u7      cursor position request (equiv. to VT100/ANSI/ECMA-48 DSR 6)
#       u6      cursor position report (equiv. to ANSI/ECMA-48 CPR)
#
# The terminal enquire string <u9> should elicit an answerback response
# from the terminal.  Common values for <u9> will be ^E (on older ASCII
# terminals) or \E[c (on newer VT100/ANSI/ECMA-48-compatible terminals).
#
# The cursor position request (<u7>) string should elicit a cursor position
# report.  A typical value (for VT100 terminals) is \E[6n.
#
# The terminal answerback description (u8) must consist of an expected
# answerback string.  The string may contain the following scanf(3)-like
# escapes:
#
#       %c      Accept any character
#       %[...]  Accept any number of characters in the given set
#
# The cursor position report (<u6>) string must contain two scanf(3)-style
# %d format elements.  The first of these must correspond to the Y coordinate
# and the second to the %d.  If the string contains the sequence %i, it is
# taken as an instruction to decrement each value after reading it (this is
# the inverse sense from the cup string).  The typical CPR value is
# \E[%i%d;%dR (on VT100/ANSI/ECMA-48-compatible terminals).
#
# These capabilities are used by tack(1m), the terminfo action checker
# (distributed with ncurses 5.0).

检查最后一条评论，钉练习u8and u9but 对u6and不执行任何操作u7。

扩展已添加1995年初:

# 9.3.4 (Wed Feb 22 19:27:34 EST 1995):
#       * Added correct acsc/smacs/rmacs strings for vt100 and xterm.
#       * Added u6/u7/u8/u9 capabilities.
#       * Added PCVT entry.

虽然它包含在多个条目中完整性（不多：18,699 行中出现了 16 次terminfo.src），该功能没有知名用户。事实上，ncurses 中有一个地方可以可以已编写使用它（一些 ifdef'd 调试代码tty_update.c文件），但使用硬编码转义序列（标记为“ANSI 兼容”）。

用户缺席的原因是：

反转任意 terminfo 表达式比看起来更难
xterm 和类似的终端解释这些转义序列

在ECMA-48，这些是（u7）数字SR（设备状态报告）和（u6）心肺复苏（活跃位置报告）。

Answer