Linux/Snippets

Hardware

• Motherboard

dmidecode -t 2

• HDD

fdisk -l
lsblk
smartctl -a /dev/sda
lshw -c disk

Packages

List packages by size

dpkg-query --show --showformat='${Package;-50}\t${Installed-Size} ${Status}\n' | sort -k 2 -n | grep -v deinstall

Sum of all installed packages

dpkg-query --show --showformat='${Package;-50}\t${Installed-Size} ${Status}\n' | sort -k 2 -n | grep -v deinstall | awk '{s+=$2} END {printf "%.0f\n", s}'

remove old kernels

dpkg -l linux-* | awk '/^ii/{ print $2}' | grep -v -e `uname -r | cut -f1,2 -d"-"` | grep -e [0-9] | xargs sudo apt-get --dry-run remove

purge all removed packages

dpkg --list | grep "^rc" | cut -d " " -f 3 | xargs sudo dpkg --purge

Processes

Measure execution time

START=$(date +%s.%N)
command
END=$(date +%s.%N)
DIFF=$(echo "$END - $START" | bc)

Wake-up and Shutdown

• shutdown and wake tomorrow

sudo rtcwake -m off -t $(data --date='1 day 6:00' +%s)

Files / Directories

Current script dir

currentpath=$(dirname "$0")
cd $currentpath

List directory sizes

clear;   for each in $(ls) ; do du -hs "$each" ; done

clear;   for each in $(ls) ; do du -hs "$each" ; done | sort -hr

find file with content

grep -iR "$PATTERN" *

find top 10 largest directories

du -hsx * | sort -rh | head -10
    h     human readable
     s    summarize
      x   one-file-system
                  r   reverse
                   h  human-numeric-sort

find files bigger than 100MB

find . -type f -size +100M
find . -type f -size +1G

find empty folders

find . -type d -empty -print
find . -type d -empty -delete

clear file content

echo "" > filename
or
for i in *; do cat /dev/null > $i; done

rename directories with spaces to underlines

find -name "* *" -type d | rename 's/ /_/g'

HDD & SSD

show hdd power states

sudo hdparm -C /dev/sd?

set hdd spindown (rc.local)

hdparm -B 250 /dev/sd?
hdparm -S 59 /dev/sd?

show SMART data

sudo smartctl -a /dev/sd?

check for bad sectors

fsck.ext4 -cDfty -C 0 /dev/sdxx

Manual SSD Trim

sudo fstrim -v /   

Cron SSD Trim

/etc/scripts/fstrim.sh:

#!/bin/sh
#
echo `date +"%d %b %H:%M:%S"` | tr -d '\n' >> /var/log/fstrim
/sbin/fstrim -v / >> /var/log/fstrim

/etc/cron.d/fstrim:

#
0 * * * * root /etc/scripts/fstrim.sh

delete folder by folder until enough free space (1G)

cd /srv/motion
while [ `df | grep /dev/root | awk '{print $4}'` -lt 1000000 ]; do
ls -r | tail -1 | xargs rm -r
sleep 5
done

Shutdown computer if HDDs idle

UPTIME=$(cat /proc/uptime | cut -d ' ' -f 1 | cut -d '.' -f 1)

if [ "$UPTIME" -lt "600" ]
  then exit
fi

lastSDB=$(cat /proc/diskstats | grep "sdb " | tr -s ' ' | cut -d ' ' -f 14 )
lastSDC=$(cat /proc/diskstats | grep "sdc " | tr -s ' ' | cut -d ' ' -f 14 )
lastSDD=$(cat /proc/diskstats | grep "sdd " | tr -s ' ' | cut -d ' ' -f 14 )

sleep 120

newSDB=$(cat /proc/diskstats | grep "sdb " | tr -s ' ' | cut -d ' ' -f 14 )
newSDC=$(cat /proc/diskstats | grep "sdc " | tr -s ' ' | cut -d ' ' -f 14 )
newSDD=$(cat /proc/diskstats | grep "sdd " | tr -s ' ' | cut -d ' ' -f 14 )

if [ "$lastSDB" = "$newSDB" ] && [ "$lastSDC" = "$newSDC" ] && [ "$lastSDD" = "$newSDD" ]
   then /sbin/shutdown -h now
   else echo "changes!!"
fi

Format ext4 with disabled lazy init

mkfs.ext4 -E lazy_itable_init=0,lazy_journal_init=0 /dev/sda1

Multimedia

• yt-dlp
  • https://github.com/yt-dlp/yt-dlp

yt-dlp --no-keep-video --extract-audio --audio-format mp3 --audio-quality 0 https://www.youtube.com/watch?