IT Solutions Technology Blog

The MAILTO environment variable in cron allows you to specify an email address to receive output from your cron job

root@rpi-samba-01:~# crontab -l
…
MAILTO=josef.schuster@dpsolution.de
# * * * * * echo „eMail Check“

01 0-23 * * * `journalctl –output=short -S yesterday| tail -c 131072 > /var/log/syslog` && `scp /var/log/syslog root@192.168.1.171:/var/log/UrgentSyslogShort.rpi-samba-01`
05 0-23 * * * `tail -c 131072 /var/log/samba/log.smbd > /var/log/smbd.log` && `scp /var/log/smbd.log root@192.168.1.171:/var/log/UrgentSambaLogShort.rpi-samba-01`

root@rpi-samba-01:~#

By default cron jobs sends an email via the MAILTO variable only if the cron job generates output (stdout or stderr) if a script runs completely error free and silently cron sends no message at all by default

root@rpi-iot-jsho-rslsync-01:~# crontab -l
…
MAILTO=josef.schuster@dpsolution.de
# * * * * * echo „eMail Check“

35 01 * * * ( export RESTIC_PASSWORD_FILE=/root/.restic-pass ; date >> /var/log/restic.local.log && restic -r /mnt/USB-Stick check && restic -r /mnt/USB-Stick forget –keep-daily 7 –keep-weekly 4 –keep-monthly 6 –prune && date >> /var/log/restic.local.log ; ) >> /var/log/restic.local.log

35 02 * * * ( export RESTIC_PASSWORD_FILE=/root/.restic-pass ; date >> /var/log/restic.extern.log && restic -r /mnt/USB-Stick.extern check && restic -r /mnt/USB-Stick.extern forget –keep-daily 7 –keep-weekly 4 –keep-monthly 6 –prune && date >> /var/log/restic.extern.log ; ) >> /var/log/restic.extern.log

05 01-23/2 * * * ( export RESTIC_PASSWORD_FILE=/root/.restic-pass ; date >> /var/log/restic.local.log && restic -r /mnt/USB-Stick backup /resilio-sync.data/USB-Stick && date >> /var/log/restic.local.log ; ) >> /var/log/restic.local.log

05 00-22/2 * * * ( export RESTIC_PASSWORD_FILE=/root/.restic-pass ; date >> /var/log/restic.extern.log && restic -r /mnt/USB-Stick.extern backup /resilio-sync.data/USB-Stick && date >> /var/log/restic.extern.log ; ) >> /var/log/restic.extern.log

root@rpi-iot-jsho-rslsync-01:~#

root@js-ubuntu-26-04-01:~# apt-get update && apt-get install msmtp msmtp-mta mailutils -y

root@js-ubuntu-26-04-01:~# msmtp –version
msmtp version 1.8.32
Platform: x86_64-pc-linux-gnu
TLS/SSL library: GnuTLS
Authentication library: GNU SASL; oauthbearer and xoauth2: built-in
Supported authentication methods:
scram-sha-256-plus scram-sha-1-plus scram-sha-256 scram-sha-1 plain gssapi external oauthbearer cram-md5 digest-md5 login ntlm xoauth2
IDN support: enabled
NLS: enabled, LOCALEDIR is /usr/share/locale
Keyring support: Gnome
System configuration file name: /etc/msmtprc
User configuration file name: /root/.msmtprc

Copyright (C) 2025 Martin Lambers and others.
This is free software. You may redistribute copies of it under the terms of
the GNU General Public License <http://www.gnu.org/licenses/gpl.html>.
There is NO WARRANTY, to the extent permitted by law.

root@js-ubuntu-26-04-01:~#

root@js-ubuntu-26-04-01:~# vi /etc/msmtprc
# Default settings
defaults
auth on
tls on
tls_trust_file /etc/ssl/certs/ca-certificates.crt
logfile /var/log/msmtp.log

# Target SMTP Server
account default
host smtp.1und1.com
port 587
from josef.schuster@dpsolution.de
user josef.schuster@dpsolution.de
password <password>

root@js-ubuntu-26-04-01:~#

root@js-ubuntu-26-04-01:~# vi /etc/aliases
root: josef.schuster@dpsolution.de
default: josef.schuster@dpsolution.de

root@js-ubuntu-26-04-01:~#

root@js-ubuntu-26-04-01:~# vi /etc/mail.rc
set sendmail=“/usr/bin/msmtp -t“

root@js-ubuntu-26-04-01:~#

root@js-ubuntu-26-04-01:~# echo „Inhalt der Mail“ | mail -s „Betreff: Mail Check“ josef.schuster@dpsolution.de

root@js-ubuntu-26-04-01:~#

root@js-ubuntu-26-04-01:~# tail  /var/log/msmtp.log
Sep 17 21:25:02 host=smtp.1und1.com tls=on auth=on user=josef.schuster@dpsolution.de from=josef.schuster@dpsolution.de recipients=josef.schuster@dpsolution.de mailsize=243 smtpstatus=250 smtpmsg=’250 Requested mail action okay, completed: id=ID‘ exitcode=EX_OK

root@js-ubuntu-26-04-01:~#

Restic – is a backup program that is fast efficient and secure

root@rpi-iot-jsho-rslsync-01:~# apt-get install restic
Reading package lists… Done
Building dependency tree… Done
Reading state information… Done
The following NEW packages will be installed:
restic
0 upgraded, 1 newly installed, 0 to remove and 0 not upgraded.
Need to get 7,575 kB of archives.
After this operation, 19.8 MB of additional disk space will be used.
Get:1 http://mirror.pyratelan.org/raspbian/raspbian bullseye/main armhf restic armhf 0.11.0-1 [7,575 kB]
Fetched 7,575 kB in 3s (2,435 kB/s)
Selecting previously unselected package restic.
(Reading database … 106673 files and directories currently installed.)
Preparing to unpack …/restic_0.11.0-1_armhf.deb …
Unpacking restic (0.11.0-1) …
Setting up restic (0.11.0-1) …
Processing triggers for man-db (2.9.4-2) …
root@rpi-iot-jsho-rslsync-01:~#

root@rpi-iot-jsho-rslsync-01:~#

root@rpi-iot-jsho-rslsync-01:~# restic version
restic 0.11.0 compiled with go1.15.7 on linux/arm

root@rpi-iot-jsho-rslsync-01:~#

root@rpi-iot-jsho-rslsync-01:~# restic self-update
writing restic to /usr/bin/restic
find latest release of restic at GitHub
latest version is 0.19.1
download SHA256SUMS
download SHA256SUMS.asc
GPG signature verification succeeded
download restic_0.19.1_linux_arm.bz2
downloaded restic_0.19.1_linux_arm.bz2
saved 28770466 bytes in /usr/bin/restic
successfully updated restic to version 0.19.1

root@rpi-iot-jsho-rslsync-01:~#

root@rpi-iot-jsho-rslsync-01:~# restic version
restic 0.19.1 compiled with go1.26.4 on linux/arm

root@rpi-iot-jsho-rslsync-01:~#

root@rpi-iot-jsho-rslsync-01:~# restic -r /mnt/USB-Stick init
enter password for new repository:
enter password again:
created restic repository c13f3caf1d at /mnt/USB-Stick

Please note that knowledge of your password is required to access
the repository. Losing your password means that your data is
irrecoverably lost.

root@rpi-iot-jsho-rslsync-01:~#

root@rpi-iot-jsho-rslsync-01:~# restic -r /mnt/USB-Stick backup /resilio-sync.data/USB-Stick
enter password for repository:
repository c13f3caf opened (version 2, compression level auto)
created new cache in /root/.cache/restic
no parent snapshot found, will read all files
[0:00] 0 index files loaded

Files: 20761 new, 0 changed, 0 unmodified
Dirs: 707 new, 0 changed, 0 unmodified
Added to the repository: 6.362 GiB (4.417 GiB stored)

processed 20761 files, 7.314 GiB in 2:41:24
snapshot 0c2f7b54 saved

root@rpi-iot-jsho-rslsync-01:~#

root@rpi-iot-jsho-rslsync-01:~# restic -r /mnt/USB-Stick snapshots
enter password for repository:
repository c13f3caf opened (version 2, compression level auto)
ID Time Host Tags Paths Size
———————————————————————————————————–
0c2f7b54 2026-09-15 14:19:23 rpi-iot-jsho-rslsync-01 /resilio-sync.data/USB-Stick 7.314 GiB
———————————————————————————————————–
Timestamps shown in local time
1 snapshots

root@rpi-iot-jsho-rslsync-01:~#

root@rpi-iot-jsho-rslsync-01:~# restic -r /mnt/USB-Stick restore latest –target /tmp/USB-Stick-Recovery
root@rpi-iot-jsho-rslsync-01:~# restic -r /mnt/USB-Stick restore <Snapshot-ID> –target /tmp/USB-Stick-Recovery

root@rpi-iot-jsho-rslsync-01:~# restic -r /mnt/USB-Stick restore 6ba46309 –target /tmp/USB-Stick-Recovery
enter password for repository:
repository c13f3caf opened (version 2, compression level auto)
[0:04] 100.00% 16 / 16 index files loaded
restoring snapshot 6ba46309 of [/resilio-sync.data/USB-Stick] at 2026-09-15 19:25:59.638884438 +0200 CEST by root@rpi-iot-jsho-rslsync-01 to /tmp/USB-Stick-Recovery
Summary: Restored 21477 files/dirs (7.315 GiB) in 53:47

root@rpi-iot-jsho-rslsync-01:~#

root@rpi-iot-jsho-rslsync-01:~# restic -r /mnt/USB-Stick forget –keep-daily 7 –keep-weekly 4 –keep-monthly 6 –prune
enter password for repository:
repository c13f3caf opened (version 2, compression level auto)
Applying Policy: keep 7 daily, 4 weekly, 6 monthly snapshots
keep 2 snapshots:
ID Time Host Tags Reasons Paths Size
————————————————————————————————————————————
0c2f7b54 2026-09-15 14:19:23 rpi-iot-jsho-rslsync-01 oldest daily snapshot /resilio-sync.data/USB-Stick 7.314 GiB
oldest weekly snapshot
oldest monthly snapshot
6ba46309 2026-09-15 19:25:59 rpi-iot-jsho-rslsync-01 daily snapshot /resilio-sync.data/USB-Stick 7.315 GiB
weekly snapshot
monthly snapshot
————————————————————————————————————————————
Timestamps shown in local time
2 snapshots

root@rpi-iot-jsho-rslsync-01:~#

root@rpi-iot-jsho-rslsync-01:~# restic -r /mnt/USB-Stick check
using temporary cache in /tmp/restic-check-cache-1548303136
create exclusive lock for repository
enter password for repository:
repository c13f3caf opened (version 2, compression level auto)
created new cache in /tmp/restic-check-cache-1548303136
load indexes
[0:06] 100.00% 16 / 16 index files loaded
check all packs
check snapshots, trees and blobs
[0:14] 100.00% 2 / 2 snapshots
no errors were found

root@rpi-iot-jsho-rslsync-01:~#

root@rpi-iot-jsho-rslsync-01:~# echo ‚<password>‘ > /root/.restic-pass && chmod 600 /root/.restic-pass

root@rpi-iot-jsho-rslsync-01:~# export RESTIC_PASSWORD_FILE=/root/.restic-pass

root@rpi-iot-jsho-rslsync-01:~#

How to add the logs to a crontab with time stamp

root@rpi-iot-jsho-rslsync-01:~# crontab -e
…
15 01 * * * ( export RESTIC_PASSWORD_FILE=/root/.restic-pass ; date >> /var/log/restic.log && restic -r /mnt/USB-Stick check && restic -r /mnt/USB-Stick forget –keep-daily 7 –keep-weekly 4 –keep-monthly 6 –prune && date >> /var/log/restic.log ; ) >> /var/log/restic.log 2>&1

05 * * * * ( export RESTIC_PASSWORD_FILE=/root/.restic-pass ; date >> /var/log/restic.log && restic -r /mnt/USB-Stick backup /resilio-sync.data/USB-Stick && date >> /var/log/restic.log ; ) >> /var/log/restic.log 2>&1

root@rpi-iot-jsho-rslsync-01:~#

root@rpi-iot-jsho-rslsync-01:~# tail -f /var/log/restic.log

Thu 17 Sep 10:10:01 CEST 2026
using parent snapshot 20842c7c

Files: 0 new, 0 changed, 20785 unmodified
Dirs: 0 new, 0 changed, 707 unmodified
Added to the repository: 0 B (0 B stored)

processed 20785 files, 7.315 GiB in 0:45
snapshot 6a96b591 saved
Thu 17 Sep 10:10:47 CEST 2026

root@rpi-iot-jsho-rslsync-01:~#

$(()) Arithmetic … e.g. echo $((10+5))

Wenn das virtuelle Dateisystem ‚efivarfs‘ voll gemeldet wird (bei df -h unter /sys/firmware/efi/efivars) liegt das daran dass der NVRAM Speicher des Mainboards erschöpft ist und häufige Folgen sind fehlschlagende Firmware- oder Secure-Boot-Updates (fwupdmgr) oder Probleme beim Ändern von Boot Einträgen

# df -h
Filesystem Size Used Avail Use% Mounted on
efivarfs 304K 113K 187K 38% /sys/firmware/efi/efivars

Amazon Linux 2027 (AL2027) – the next version of the Amazon Linux operating system purpose built for cloud native workloads on AWS with performance scale  and security in mind