This post is older than a year. Consider some information might not be accurate anymore.
Using Linux you can monitor processes with watch. It executes a program periodically, showing the output in full screen.
This example monitors every 10 seconds if the logstash process is alive. We exclude the grep command itself.
watch -n 10 "ps auxww | grep \[l\]ogstash"
To monitor the database PostgreSQL, every process, that starts with postgres:
watch "ps auxww | grep ^postgres"
Example output
$ ps auxww | grep ^postgres
postgres 960 0.0 1.1 6104 1480 pts/1 SN 13:17 0:00 postgres -i
postgres 963 0.0 1.1 7084 1472 pts/1 SN 13:17 0:00 postgres: writer process
postgres 965 0.0 1.1 6152 1512 pts/1 SN 13:17 0:00 postgres: stats collector process
postgres 998 0.0 2.3 6532 2992 pts/1 SN 13:18 0:00 postgres: tgl runbug 127.0.0.1 idle
postgres 1003 0.0 2.4 6532 3128 pts/1 SN 13:19 0:00 postgres: tgl regression [local] SELECT waiting
postgres 1016 0.1 2.4 6532 3080 pts/1 SN 13:19 0:00 postgres: tgl regression [local] idle in transaction
