普通用户在 /var/run 中触摸文件失败

Question

I have a program called HelloWorld belonging to user test

HelloWorld will create a file HelloWorld.pid in /var/run to keep single instance. I using following command to try to make test can access /var/run

usermod -a -G root test

However, when I run it, falied

could someone help me?

Answer 1

What are the permissions on /var/run ? On my system, /var/run is rwxr-xr-x , which means only the user root can write to it. The permissions do not allow write access by members of the root group.

The normal way of handling this is by creating a subdirectory of /var/run that is owned by the user under which you'll be running your service. Eg,

sudo mkdir /var/run/helloworld
sudo chown myusername /var/run/helloworld

Note that /var/run is often an ephemeral filesystem that disappears when your system reboots. If you would like your target directory to be created automatically when the system boots you can do that using the systemd tmpfiles service.

Answer 2

Some linux systems store per-user runtime files in /var/run/user/UID/ .

In this case you can create your pid file in /var/run/user/$(id -u test)/HelloWorld.pid .

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Alternatively just use /tmp .

You may want to use the user's name as a prefix to the pid filename to avoid collision with other users, for instance /tmp/test-HelloWorld.pid .