Tips on Some Stat Commands for FreeBSD

FreeBSD provides some handy commands to get various information:  Command netstat shows network status, sockstat lists open sockets, fstat identifies active files, and procstat gets detailed process information. Here are some tips on their usages.

1. Show Internet routing table:

netstat -rn

2. Show all active Internet (IPv4) connections (including servers):
netstat -f inet -a -n
or,
sockstat -4
which gives us more information on command name and process identifier (PID) for each connection.

3. Show all Active TCP connections (including servers):
netstat -f inet -p tcp -a -n
or,
sockstat -4 -P tcp

4. Identify processes using a file or directory:
fstat -v /path/to/the/fileORdirectory

5. Identify all files opened by the specified process:
fstat -v -p PID
or,
procstat -f PID

6. Identify all files opened by the specified user:
fstat -v -u user

7. Get detailed process information on all processes:
procstat -a

8. Get environment variables on the specified process:
procstat -e PID