System Administration Guide: Network Services

truss Command

You can use this command to check if a process is hung. The truss command must be run by the owner of the process or by root. You can use many options with this command. See the truss(1) man page. A shortened syntax of the command follows.

truss [ -t syscall ] -p pid

-t syscall

Selects system calls to trace

-p pid

Indicates the PID of the process to be traced

The syscall can be a comma-separated list of system calls to be traced. Also, starting syscall with an ! selects to exclude the listed system calls from the trace.

This example shows that the process is waiting for another connection request from a new client.

# /usr/bin/truss -p 243
poll(0x00024D50, 2, -1)         (sleeping...)

The previous example shows a normal response. If the response does not change after a new connection request has been made, the process could be hung. Follow the instructions in How to Restart NFS Services to fix the hung program. Review the instructions in NFS Troubleshooting Procedures to fully verify that your problem is a hung program.