如何使用Golang导入/加载/运行mysql文件？

Question

I'm trying to run/load sql file into mysql database using this golang statement but this is not working:

exec.Command("mysql", "-u", "{username}", "-p{db password}", "{db name}", "<", file abs path )

But when i use following command in windows command prompt it's working perfect.

mysql -u {username} -p{db password} {db name} < {file abs path}

So what is the problem?

Answer 1

As others have answered, you can't use the < redirection operator because exec doesn't use the shell.

But you don't have to redirect input to read an SQL file. You can pass arguments to the MySQL client to use its source command.

exec.Command("mysql", "-u", "{username}", "-p{db password}", "{db name}",
    "-e", "source {file abs path}" )

The source command is a builtin of the MySQL client. See https://dev.mysql.com/doc/refman/5.7/en/mysql-commands.html

Answer 2

Go's exec.Command runs the first argument as a program with the rest of the arguments as parameters. The '<' is interpreted as a literal argument.

eg exec.Command("cat", "<", "abc") is the following command in bash: cat \\< abc .

To do what you want you have got two options.

• Run (ba)sh and the command as argument: exec.Command("bash", "-c", "mysql ... < full/path")
• Pipe the content of the file in manually. See https://stackoverflow.com/a/36383984/8751302 for details.

The problem with the bash version is that is not portable between different operating systems. It won't work on Windows.

Answer 3

Go's os.exec package does not use the shell and does not support redirection:

Unlike the "system" library call from C and other languages, the os/exec package intentionally does not invoke the system shell and does not expand any glob patterns or handle other expansions, pipelines, or redirections typically done by shells.

You can call the shell explicitly to pass arguments to it:

cmd := exec.Command("/bin/sh", yourBashCommand)

Depending on what you're doing, it may be helpful to write a short bash script and call it from Go.