Here is how to manually restart or stop Virtuoso from the command line.

The following article was used as a reference.

how to manually restart or stop virtuoso from commandline
I have a new installed Virtuoso (from github > 7.2.4) on a Debian jessie system. It starts properly after boot. How to stop, start, and restart manually the virtuoso web server? It starts after re...
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The following approach seems to work well.

isql {host}:{port} {UID} {PWD} EXEC=shutdown

A specific example is as follows.

isql localhost:1111 dba dba EXEC=shutdown

If isql is not found as shown below, change the path and execute.

isql localhost:1111 dba dba EXEC=shutdown
bash: isql: command not found

find / -name isql
/usr/local/bin/isql
/root/virtuoso-opensource/binsrc/tests/isql

/usr/local/bin/isql localhost:1111 dba dba EXEC=shutdown

I hope this serves as a helpful reference.