Executing a tar command from within a Go program

[Dean Schulze]

I need to execute this tar command 

tar xzf dir1/dir2/somefile.tgz --directory=dir1/dir2/

from within a Go program.  I've verified that it works from the command line.  I've tried using

argStr := "xzf dir1/dir2/somefile.tgz --directory=dir1/dir2/"
output, err := exec.Command("tar", argStr).Output()

but it returns an error code of 2 with no other output indicating what is wrong.

Using exec.Command(name, arg) is always a guessing game as to what the command name should be and what the argument should be.  How do I execute this tar command from within Go?

[wagner riffel]

On Wed Apr 20, 2022 at 6:16 PM CEST, Dean Schulze wrote:
> I need to execute this tar command
>

> *tar xzf dir1/dir2/somefile.tgz --directory=dir1/dir2/*
>

Did you considered using the packages "archive/tar" and
"compress/gzip" to achive this?

> *argStr := "xzf dir1/dir2/somefile.tgz --directory=dir1/dir2/"output, err
> := exec.Command("tar", argStr).Output()*
>

exec.Command arguments are variadic, each argument is one argv, thus I
think you meant exec.Command("tar", "xzf", "dir1/dir2/somefile.tgz",
"--directory=dir1/dir2/")

-w

[wagner riffel]

Also, the Output method only returns what was wrote to stdout, tar
argument parsing errors are probably in stderr, using CombinedOutput()
has better effect to debug.

[Axel Wagner]

On Wed, Apr 20, 2022 at 6:16 PM Dean Schulze <dean.w....@gmail.com> wrote:

I need to execute this tar command 

tar xzf dir1/dir2/somefile.tgz --directory=dir1/dir2/

from within a Go program.  I've verified that it works from the command line.  I've tried using

argStr := "xzf dir1/dir2/somefile.tgz --directory=dir1/dir2/"
output, err := exec.Command("tar", argStr).Output()

You need to pass the args separately, not as one string:

output, err := exec.Command("tar", "xzf", "dir1/dir2/somefile.tgz", "--directory=dir1/dir2/").Output()

I also tend to set `cmd.Stderr = os.Stderr` to make sure I see error messages, when executing commands.

 

but it returns an error code of 2 with no other output indicating what is wrong.

Using exec.Command(name, arg) is always a guessing game as to what the command name should be and what the argument should be.  How do I execute this tar command from within Go?

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[Dean Schulze]

The variadic args worked perfectly.  Thanks.

I did not use the archive/tar and compress/gzip approach because that wold be a lot more complicated than just executing a tar command.  Those packages are oriented towards reading/writing the contents of archive/compressed files into the program rather than just extracting a file from a compressed archive.