如何使用SshClient将内容写入Linux SFTP服务器上的文件?

问题描述：

我正在使用.Net(SshClient)代码处理Linux SFTP服务器，因此我正在SFTP服务器上创建文件夹并也创建文件.为此，我正在使用以下代码，

I am dealing with Linux SFTP server using .Net (SshClient) code, so I am creating folder on SFTP server and creating files also. For this I am using following code,

using (var client = new SshClient(WebConfigurationManager.AppSettings["SftpServer"], WebConfigurationManager.AppSettings["SftpUserName"], WebConfigurationManager.AppSettings["SftpPassword"]))
{
   client.Connect();

    if (client.IsConnected)
    {
        //  Check if the Folder Already Exists 
        var ifExists = client.RunCommand("cat /etc/passwd  | grep -w " + ftpUserName);
        // If the Folder and User Does Not exists , create both 
        if (string.IsNullOrEmpty(ifExists.Result))
        {
            client.RunCommand("echo Asdf@123 | sudo -S mkdir /sftpusers/" + ftpUserName);
            client.RunCommand("echo Asdf@123 | sudo -S mkdir /sftpusers/" + ftpUserName + "/import"); //  this is for creating folder
            client.RunCommand("echo Asdf@123 | sudo -S mkdir /sftpusers/" + ftpUserName + "/schema");
            client.RunCommand("echo Asdf@123 | sudo -S touch /sftpusers/" + ftpUserName + "/schema/fileName.txt");
            sftpCreated = true;
        }
    }
    client.Disconnect();
}

此代码是在SFTP上创建文件夹和文本文件的工作文件，但是现在我试图将数据写入该文件，为此，我正在使用以下代码，

This code is working file to create a folder and text files on SFTP but Now I am trying to write data to that file, and for that I am using following code,

client.RunCommand("echo Asdf@123 | sudo -S echo hi user >> /sftpusers/asb/schema/filename.txt");

但是它不起作用. Error = "bash: /sftpusers/asb/schema/filename.txt: Permission denied\n.

如果使用相同的命令，即echo pwd | sudo -s cmd 在SFTP服务器上创建文件夹，文件，然后为什么在将内容写入文件时失败.

I am little confused that, if same command i.e. echo pwd | sudo -s cmd is creating folder, files on SFTP server then why it failing while writing content to file.

在此方面需要尽快的帮助.

Need help on this as early as possible.

答

sudo touch ./blabla

将创建具有根(！)权限的root用户的blabla文件.该文件的所有者将是root，并且很可能只允许root用户写入.

Will create a blabla file as root with root(!) permissions. The owner of this file will be root and most probably the write will be only allowed for root.

sudo echo 123 > ./blabla

这将以root用户身份执行echo，并以shell(！)用户的身份将输出重定向到blabla. sudo使命令echo以root身份运行.但是重定向>是由外壳程序完成的，而不是由sudo完成.因此，重定向是通过打开外壳程序来完成的，对于您而言，不是由非root用户(无法访问该文件)来完成的.

This will execute echo as root, and redirect the output to blabla as the shell(!) user. sudo makes the command echo run as root. But the redirection > is done by the shell, not by sudo. So the redirection is done by the however opened the shell, in your case by a user that isn't root, who can't access the file.

您必须以root用户身份写入文件才能正常工作.您可以以root用户身份运行子shell:

You have to write to the file as root for it to work. You can run a subshell as root:

echo 123 | sudo sh -c 'cat > ./blabla'
// or better for scripting, cause no double quoting is needed
echo 123 | sudo sh -c 'cat > "$1"' -- ./blabla

这将echo 123并以root用户身份执行sh，并使用命令cat重定向到脚本的第一个参数，即blabla.请注意，由于Shell以root身份运行，因此重定向也以root身份完成，因此Shell能够打开并写入文件.

This will echo 123 and execute sh as root with the command cat redirected to the first argument of the script, that is blabla. Note that as the shell is run as root, the redirection is also done as root, so the shell is able to open and write to the file.

或者，更干净的方法是制作tee.

Alternatively a more clean approach is to make a tee.

echo 123 | sudo tee blabla >/dev/null

请记住将tee的标准输出重定向为null，这样它就不会打印任何内容.

Remember to redirect tee's stdout to null, so it doesn't print anything.

做:

 client.RunCommand("echo Asdf@123 | sudo -S sh -c 'echo hi user >> "$1"' -- /sftpusers/asb/schema/filename.txt");

请注意，因为您使用sudo -S来读取密码(这是不安全的并且很糟糕)，所以不能使用stdin将写入的字符串传递给tee.

Note that because you use sudo -S to read the password (which is unsafe and kind of bad), you can't use stdin to pass written string to tee.

如何使用SshClient将内容写入Linux SFTP服务器上的文件?

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