On Sat, May 25, 2019 at 06:21:27PM -0700, L A Walsh wrote: > Problem happened when I re-used a var that had earlier had the > integer property set on the variable. > > declare -i a=123
That's (part of) why I strongly recommend that nobody ever use that -i flag. > then later > a="▯" > -bash: ▯: syntax error: operand expected (error token is "▯") > (u+25AF) Sounds reasonable. > I'm still not sure why it is giving a syntax error when > a="t", for example doesn't (it puts a value of '0' in 'a'). Because the variable t is probably not set. > But if I try: > a="z", I get the syntax error again(**) > (**) - because in coming up with test cases, I had tried > assigning that 'u+25af' (▯) to 'z', oh ...just weird. And that's why. Remember, in a math context, bash variables undergo recursive expansions. Using declare -i forces *every* assignment to this variable to operate in a math context instead of a string context. > Ideally, I'd prefer to see something like printf > prints out when it finds a non number for a decimal field: > > printf "%d" "t" > -bash: printf: t: invalid number > It would really be better if it could say what it > was expecting, like printf. It told you what it expected: an "operand". You're performing an assignment in a math context, so what it's expecting is, ultimately, a valid integer expression. Bash will recursively resolve anything that looks like a variable name as another math expression, defaulting to 0 for empty/unset expressions. When the math parser runs into something like é that can't be a variable name and can't be parsed as an integer expression, it throws a syntax error. wooledg:~$ let x=é bash: let: x=é: syntax error: operand expected (error token is "é") wooledg:~$ let x=% bash: let: x=%: syntax error: operand expected (error token is "%") wooledg:~$ let x=1+ bash: let: x=1+: syntax error: operand expected (error token is "+") Looks like it just uses that one syntax error for all the cases. Unwinding the state within the math parser to try to give a more descriptive error message is probably difficult.
