17.10.2017
- Create unit file which will write "Hello!" into file located at /tmp/hello after executing.
Create a script.
touch /tmp/hello-script
Write this to the script.
#!/usr/bin/bash
echo "HELLO" >> /tmp/hello
Change file mode bits.
chmod +x /tmp/hello-script
Create a unit file.
touch /etc/systemd/system/hello.service
Write this to the unit file.
[Unit]
Description=Baz Service
[Service]
Type=simple
ExecStart=/tmp/hello-script
StandardError=journal
TimeoutStopSec=5
Start the service.
systemctl start hello.socket
systemctl status hello.socket
Verify it.
cat /tmp/hello
- We would like to run a service on port 9999 using socket and when somebody is connected on this port we write current time of the connection into file.
Create a unit file1.
touch /etc/systemd/system/baz.socket
Write this to the unit file1.
[Unit]
Description=Baz Socket
[Socket]
ListenStream=127.0.0.1:9999
Accept=yes
[Install]
WantedBy=sockets.target
Create a unit file2.
touch /etc/systemd/system/baz@.service
Write this to the unit file2.
[Unit]
Description=Baz Service
Requires=baz.socket
[Service]
Type=simple
ExecStart=/tmp/myscript
StandardInput=socket
StandardError=journal
TimeoutStopSec=5
[Install]
WantedBy=multi-user.target
Create a script.
touch /tmp/myscript
Write this to the script.
#!/usr/bin/bash
date >> /tmp/datenow.txt
Start the service.
systemctl start baz.socket
systemctl status baz.socket
Verify it.
cat /tmp/hello
- Create templates as abc@hello which will do the 1 tast, and abc@ ...
# ...
- Create three loopback devices and RAID-5 on these devices.
fallocate -l 100M file0
fallocate -l 100M file1
fallocate -l 100M file2
losetup -f file0
losetup -f file1
losetup -f file2
mdadm --create --verbose /dev/md0 -l 5 -n 3 /dev/loop0 /dev/loop1 /dev/loop2
mkfs.ext4 /dev/md0
Create a unit file.
touch /etc/systemd/system/raid.service
Write this to the unit file.
[Unit]
Description=Baz Service
[Service]
Type=simple
ExecStart=/tmp/raid
StandardError=journal
TimeoutStopSec=5
Create a script.
touch /tmp/raid
Write this to the script.
#!/usr/bin/bash
fallocate -f file0
fallocate -f file1
fallocate -f file2
Start the service.
systemctl start baz.socket
systemctl status baz.socket