鉴于此驱动程序功能仅在给定特定输入的情况下产生输出:
function driver -a arg
test $arg = 1; and echo OK
return 0
end
当函数发出输出时,一切正常:
$ driver 1 | od -c
0000000 O K \n
0000003
$ test -z (driver 1); and echo no output; or echo some output
some output
$ test -n (driver 1); and echo some output; or echo no output
some output
但在没有输出的情况下:
$ driver 0 | od -c
0000000
$ test -z (driver 0); and echo no output; or echo some output
no output
$ test -n (driver 0); and echo some output; or echo no output
some output
这是一个错误吗?