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  • i think this must be the only way, really. if the terminal doesn't support double-width chars, then it doesn't much matter what wcswidth() has to say about anything at all. Commented Nov 23, 2015 at 23:22
  • In practice, the only problem I've had with this method is plink, which sets TERM=xterm even though it doesn't respond to any control sequence. But I don't use very exotic terminals. Commented Nov 24, 2015 at 0:15
  • Thanks. but the idea was to get that information prior to display the string on the terminal (to know where to display it, that's a follow-up on the recent question about displaying a string on the right of the terminal, maybe I should have mentioned that though my real question was really about how to get to wcswidth from the shell). @mikeserv, yes wcswidth() may be wrong about how a specific terminal would display a particular string, but that's as close as you can get to a terminal-independant solution and that's what col/ksh-printf use on my system. Commented Nov 24, 2015 at 11:54
  • I'm aware of that, but wcswidth isn't directly accessible except via less-portable features (you could do this in perl, by making some assumptions - see search.cpan.org/dist/Text-CharWidth/CharWidth.pm). The right-alignment question by the way could be (perhaps) improved by writing the string to the lower-left and then using the cursor-position and insert-controls to shift it to the lower-right. Commented Nov 24, 2015 at 11:59
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    @StéphaneChazelas - fold is apparently spec'd to handle multi-byte and extended width characters. Here's how it should handle backspace: The current count of line width shall be decremented by one, although the count never shall become negative. The fold utility shall not insert a <newline> immediately before or after any <backspace>, unless the following character has a width greater than 1 and would cause the line width to exceed width. maybe fold -w[num] and pr +[num] could be teamed up somehow? Commented Nov 24, 2015 at 14:26