Oh! Thank you Kurtis. So do you have a special Editor to inform you about
the functions? My current editor cannot even tell what type of variable a
go function would return, let alone parameter hints, etc.
On Mon, Jun 9, 2025 at 1:50 PM Kurtis Rader <kra...@skepticism.us> wrote:
>
>
> On Sun, Jun 8, 2025 at 9:35 PM Zhaoxun Yan <yan.zhao...@gmail.com> wrote:
>
>> it turned out to be an error misjudgement. The real line that caused
>> trouble is this:
>> s = er.Error()+string(out)
>> The error is gone after I changed it to this line :
>> s = fmt.Sprintf("%v %s", er, out)
>>
>
> The stdlib os.exec.Command()
> <https://pkg.go.dev/os/exec@go1.24.4#Command>function
> only returns a single value. Which should result in a compiler error since
> your program expects two values. I'm going to guess that you are calling a
> different function with that name which can return two values and the "er"
> return value can be nil. Which would result in the "er.Error()" call to
> dereference a nil value. So I think you have incorrectly diagnosed the
> cause of the problem. The first statement does not correctly handle "er"
> being nil. The "fmt.Sprintf()" correctly handles "er" being the nil value.
>
>
>> On Fri, Jun 6, 2025 at 6:29 PM Zhaoxun Yan <yan.zhao...@gmail.com> wrote:
>>
>>> --------------------
>>> panic: runtime error: invalid memory address or nil pointer dereference
>>> [signal SIGSEGV: segmentation violation code=0x1 addr=0x18 pc=0x6646f2]
>>>
>>> goroutine 1 [running]:
>>> util.CommandArgs({0xc000093cb0?, 0x2?, 0xc000071380?})
>>> /home/zxun/src/util/util.go:49 +0xf2
>>> --------------------
>>> This error occurred because package [main] uses a function called
>>> "CommandArgs" from my self-built package [util] with args in another
>>> package [conf] in the same directory. Package [util] got lost because it
>>> does not know where is package [conf]
>>> like this
>>> [util] /home/zxun/src/util.go
>>> [conf] /home/zxun/src/conf.go
>>> [main] /home/zxun/src/main.go...
>>> /home/zxun/src/go.mod:
>>>
>>> require(
>>> util v0.0.0
>>> ...
>>> replace util => ../util
>>>
>>> The usage line in main.go:
>>> fmt.Println( util.CommandArgs([]string{conf.IreportExec,
>>> conf.IreportScript, "redis"}) )
>>>
>>> util.CommandArgs:
>>>
>>> func CommandArgs(args []string) string{
>>> if len(args) ==0{
>>> return "args are empty！"
>>> }
>>> var s string
>>> if len(args) ==1{
>>> out, er := exec.Command(args[0]).CombinedOutput()
>>> s = er.Error()+string(out)
>>> }else{
>>> out, er := exec.Command(args[0],args[1:]...).CombinedOutput()
>>> s = er.Error()+string(out)
>>> fmt.Println(s)
>>> }
>>> return s
>>> }
>>>
>>> So is my analysis correct? I have not seen s printed yet, because s
>>> shall include "<nil>" at the beginning. I am using go1.18. If the cause is
>>> util package cannot access a variable in conf, is it possible to walk
>>> around by a deepcopy of the string array (which will be in package main)?
>>>
>>> Thanks in advance.
>>>
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>> .
>>
>
>
> --
> Kurtis Rader
> Caretaker of the exceptional canines Junior and Hank
>
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