Java 将进程作为后台服务运行会导致异常
下面的代码Java 将进程作为后台服务运行会导致异常,java,linux,file-permissions,permission-denied,Java,Linux,File Permissions,Permission Denied,下面的代码 try { String fileName = "/var/log/syslog"; File myFile = new File(fileName); FileInputStream myStream = null; System.out.println("canRead() returns " + myFile.canRead ()); System
try {
String fileName = "/var/log/syslog";
File myFile = new File(fileName);
FileInputStream myStream = null;
System.out.println("canRead() returns " + myFile.canRead ());
System.out.println("canWrite() returns " + myFile.canWrite());
myStream = new FileInputStream(myFile);
myStream.close();
}
catch (FileNotFoundException e)
{
System.out.println("FileNotFoundException: " + e);
}
catch (IOException e)
{
System.out.println("IOException: " + e);
}
投掷
java.io.FileNotFoundException: /var/log/syslog (Permission denied)
当作为后台服务运行时
sudo start server
但在作为前台任务运行时成功
exec bin/server.sh
该文件已存在:
niru@node2:~$ ls -l /var/log/syslog
-rw-r----- 1 syslog adm 616642 Sep 6 15:59 /var/log/syslog
niru用户ID具有文件的读取权限:
niru@node2:~$ id -a niru
uid=2001(niru) gid=2001(niru) groups=2001(niru),4(adm),27(sudo)
niru@node2:~$ head -3 /var/log/syslog
Aug 1 15:47:57 node kernel: imklog 5.8.6, log source = /proc/kmsg started.
Aug 1 15:47:57 node rsyslogd: [origin software="rsyslogd" swVersion="5.8.6" x-pid="535" x-info="http://www.rsyslog.com"] start
Aug 1 15:47:57 node rsyslogd: rsyslogd's groupid changed to 103
有人能告诉我这是什么原因吗?通过运行
sudo start server
进程不再以用户niru
的身份运行,因此无法再访问系统日志文件。此权限问题是因为在Debian发行版上运行服务的用户的凭据与用户的凭据
This bug in Upstart is documented here: https://bugs.launchpad.net/upstart/+bug/812870
例如,当以“niru”用户id登录时,“id-a”命令返回以下输出:
niru@node2:~$ id -a
uid=2001(niru) gid=2001(niru) groups=2001(niru),4(adm),27(sudo)
在服务流程的上下文中,相同的“id-a”命令返回:
uid=2001(niru) gid=2001(niru) groups=2001(niru)
因此,在服务上下文中,niru用户ID没有读取/var/log/syslog文件的权限
This bug in Upstart is documented here: https://bugs.launchpad.net/upstart/+bug/812870
将setgid参数添加到服务启动文件中解决了问题。但当我对该进程进行ps时,我将用户视为niru。那么原因是什么呢?很好,用户niru拥有sudo权限。