Ubuntu prompts Syntax error: Bad for loop variable when performing arithmetic operations

Syntax error: Bad for loop variable solution: a simple shell script is written in Ubuntu .. do .. done Structure Calculation 1 + 2 + 3 ...... if the value is greater than 100, an error is always returned. Www.2cto.com Script :#! /Bin/bash # information PATH =/bin:/sbin:/usr/bin:/usr/sbin:/usr/local/bin:/usr/local/sbin :~ /Binexport PATH read-p "Please input a num" numsum = 0for (a = 0; a <= $ num; a = a + 1 )) do sum = $ ($ sum + $ a) doneecho "the sum is => $ sum" exit 0 error Syntax error: Bad for loop variable solution:

Sudo dpkg-reconfigure dash select No www.2cto.com from the options of ubuntu 6.10, ubuntu will replace the previous default bash shell with the dash shell; the result is that/bin/sh links down/bin/dash instead of the traditional/bin/bash. Ubuntu edgy is the first version released with dash as the default shell, which seems to be affected by debian. There is an official explanation in the wiki, https://wiki.ubuntu.com/dashasbinsh. the main reason is that dashis smaller, runs faster, and is compatible with posix. However, the current problem is that the shell replacement causes many script errors. After all, many of the current scripts are not 100% POSIX compatible. As mentioned in the wiki, if he changes the default shell back to bash, the method is to execute sudo dpkg-reconfigure dash on the terminal and select no from the column csh159.