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## Re: Order of command substitution and arithmetic expansion

**From**: |
Dongbo Hu |

**Subject**: |
Re: Order of command substitution and arithmetic expansion |

**Date**: |
Sat, 13 Nov 2021 14:21:55 -0500 |

>* If arithmetic expansion happened last in all cases, then the first result *
>* should have been the same as the second result.*
Thank you for your reply. I suppose you meant "If arithmetic expansion happened
last in all cases, then the first result should have been DIFFERENT from the
second result?
One reason that I asked this question is because O’Reilly book “Learning the
bash shell” (by Cameron Newham and Bill Rosenblatt, 3rd Edition, 2005) claimed
that command substitution is before arithmetic expansion (pp180-182), and I
never doubted it until reading the reference manual recently.
I also took a quick look at the source code, but it’s a little complex and I
can’t tell for sure the exact order. Interestingly, the comments in source code
always put command substitution before arithmetic expansion.