How I can translate this shell command to golang code?

[Franco Marchesini]

Help,

how I can translate this shell command :

echo -n 123456 | dmtxwrite -s 16x48  -o image.png

to golang

 exec.Commad()

Thanks in advance

Franco

[Jan Mercl]

On Mon, Jun 22, 2020 at 5:54 PM Franco Marchesini
<franco.m...@gmail.com> wrote:

> how I can translate this shell command :
>
> echo -n 123456 | dmtxwrite -s 16x48 -o image.png

Not tested: https://play.golang.org/p/Jh9ix17TlKG

[Michael Jones]

https://tutorialedge.net/golang/executing-system-commands-with-golang/

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Michael T. Jones
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[Tyler Compton]

I just want to highlight an easy mistake to make here. One might expect to be able to run something like this:

exec.Command("echo", "-n", "123456", "|", "dmtxwrite", "-s", "16x48", "-o", "image.png")

But, as you might have found, this doesn't work. This is because the pipe "|" is an operator implemented by shells like sh and bash. As mentioned in the overview of the os/exec package, the package never invokes your shell automatically, so operators like the pipe operator are not available by default. Jan's answer works because it invokes the shell explicitly to run your command.

[Bakul Shah]

You can avoid calling the shell by observing that you are simply passing "123456" as input, which you can do in a Go Program itself.

See https://golang.org/pkg/os/exec/#example_Command

[Franco Marchesini]

Ciao,

I had read this tutorial, but  my mistake was not having called the shell command

Il giorno lunedì 22 giugno 2020 18:01:04 UTC+2, Michael Jones ha scritto:

https://tutorialedge.net/golang/executing-system-commands-with-golang/

On Mon, Jun 22, 2020 at 8:54 AM Franco Marchesini <franco.m...@gmail.com> wrote:

Help,

how I can translate this shell command :

echo -n 123456 | dmtxwrite -s 16x48  -o image.png

to golang

 exec.Commad()

Thanks in advance

Franco

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[Michael Jones]

Bakul's answer is best... starting the shell, the shell pipeline, etc. is not free in execution time and memory use. The "do it all in dmtxwrite by sending input" is the fastest, lightest way of doing what you want.

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[Franco Marchesini]

Yes, this is better.

Thanks

func main() { cmd := exec.Command("dmtxwrite", "-s", "16x48", "-o", "image2.png")
 cmd.Stdin = strings.NewReader("123456")
 if err := cmd.Run(); err != nil {
 panic(err.Error())
 }
}

Il giorno lunedì 22 giugno 2020 18:19:36 UTC+2, Bakul Shah ha scritto:

You can avoid calling the shell by observing that you are simply passing "123456" as input, which you can do in a Go Program itself.

See https://golang.org/pkg/os/exec/#example_Command

On Jun 22, 2020, at 8:54 AM, Franco Marchesini <franco.m...@gmail.com> wrote:

Help,

how I can translate this shell command :

echo -n 123456 | dmtxwrite -s 16x48  -o image.png

to golang

 exec.Commad()

Thanks in advance

Franco

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