
Category: System
TOTD: Append local file to remote file via SSH
Sometimes it’s handy to be able to directly append to a remote file. Here is how to do it simply:
cat my_file | ssh user@host 'dd of=/home/user/outfile oflag=append conv=notrunc'
#TipOfTheDay
Cargo Cult Sytem Administrator
And some other types too.
Fun article to read here: https://blog.lastinfirstout.net/2009/11/cargo-cult-system-administration.html
One particularly right: “Asserting that [Technology O] or [Platform L] or [Methodology A] is inherently superior to all others and blindly applying it to all problems. When you make such claims, are you applying science or religion?”
“It’s easy to fall into cargo cult mode.
Just re-boot it, it’ll be fine.” – Michael Janke
Clean cache to reclaim memory without a reboot
Tip submitted by my friend J.K when we were in need of a way to recover reserved cache space without booting.
In root:
PageCache only: sync ; echo 1 > /proc/sys/vm/drop_caches Dentries and inodes: sync ; echo 2 > /proc/sys/vm/drop_caches PageCache, Dentries and inodes: (not recommanded in production as it forces a full cache rebuilt. you may still need it): sync ; echo 3 > /proc/sys/vm/drop_caches
In case you need to do it in a sudo:
echo 3 | sudo tee /proc/sys/vm/drop_caches
Syslog, rsyslogd: change output format to display log level and facilities
If ever you need to sort log messages by their log level yo may need to change the default output format of the syslog.
For rsyslog it’s located in /etc/rsyslogd.conf. Add these lines after the line “$ActionFileDefaultTemplate RSYSLOG_TraditionalFileFormat” :
$template precise,”%timegenerated% %HOSTNAME% {%syslogpriority%,%syslogfacility%} %syslogtag% %msg%\n”
$ActionFileDefaultTemplate precise
Then restart rsyslogd:
sudo service rsyslog restart
#rsyslogd #syslog #log #loglevel #facilities