Linux Process Manager: Upstart
2 minute read
Definiation:
Upstart is an event-based replacement for the /sbin/init daemon which handles starting of tasks and services during boot, stopping them during shutdown and supervising them while the system is running.
Upstart Processes reside in /etc/init/
Go to process directory
cd /etc/init/
Create Conf file
Create your process config file in there
e.g process_name.conf using your preferred editor.
vim process_name.conf
example of Upstart config file:
description "Job that runs the foo daemon"
# start in normal runlevels when disks are mounted and networking is available
start on runlevel [2345]
# stop on shutdown/halt, single-user mode and reboot
stop on runlevel [016]
env statedir=/var/cache/foo
# create a directory needed by the daemon
pre-start exec mkdir -p "$statedir"
exec /usr/bin/foo-daemon --arg1 "hello world" --statedir "$statedir"
Check Syntax
Check your process conf file for syntax errors using:
init-checkconf -d /etc/init/process_name.conf
Reload Upstart
Relaod upstart to recognise your process
initctl reload-configuration
Control your process
Control the process using:
sudo start | stop process_name
Upstart vs Systemd Commands
| Operation | Upstart Command | Systemd equivalent | Notes |
|---|---|---|---|
| Start service | start $job | systemctl start $unit or service $unit start | |
| Stop service | stop $job | systemctl stop $unit or service $unit stop | |
| Restart service | restart $job | systemctl restart $unit or service $unit restart | |
| See status of services | initctl list | systemctl list or service –status-all | |
| Check configuration is valid | init-checkconf /etc/init/$job.conf | systemd-analyze verify <unit_file> | |
| Show job environment | initctl list-env | systemctl show-environment | |
| Set job environment variable | initctl set-env foo=bar | systemctl set-environment foo=bar | |
| Remove job environment variable | initctl unset-env foo | systemctl unset-environment foo | |
| View job log | cat /var/log/upstart/$job.log | sudo journalctl -u $unit | |
| tail -f job log | tail -f /var/log/upstart/$job.log | sudo journalctl -u $unit -f | |
| Show relationship between services | initctl2dot | systemctl list-dependencies –all |
More detailed explanation to the slightest differences between Upstart and Systemd can be found here: https://wiki.ubuntu.com/SystemdForUpstartUsers