json - 为什么 jq 1.6 不接受这个 "if A then B end"语句？

Question

根据jq手册(条件和比较> if-then-else):

if A then B end is the same as if A then B else . end. That is, the else branch is optional, and if absent is the same as ..

这个 Stack Overflow 问题的公认答案也证实了这一点:JSON JQ if without else

那么为什么这个if A then B end语句会引发解析错误？

$ jq --version
jq-1.6
$ echo 2 | jq 'if . == 0 then "zero" end'
jq: error: syntax error, unexpected end (Unix shell quoting issues?) at <top-level>, line 1:
if . == 0 then "zero" end                      
jq: error: Possibly unterminated 'if' statement at <top-level>, line 1:
if . == 0 then "zero" end
jq: 2 compile errors
$ echo 0 | jq 'if . == 0 then "zero" end'
jq: error: syntax error, unexpected end (Unix shell quoting issues?) at <top-level>, line 1:
if . == 0 then "zero" end                      
jq: error: Possibly unterminated 'if' statement at <top-level>, line 1:
if . == 0 then "zero" end
jq: 2 compile errors

我理解的等价 if A then B else 。 end 形式的语句似乎有效:

$ echo 2 | jq 'if . == 0 then "zero" else . end'
2
$ echo 0 | jq 'if . == 0 then "zero" else . end'
"zero"

Answer 1

我认为您正在查看 manual for the development version of jq ，而不是the manual for jq version 1.6 .