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Ubuntu

General commands

  • dpkg --print-foreign-architectures - Get foreign architecture
  • dpkg --print-architecture - Get native architecture
  • cat /var/lib/dpkg/arch - Available architecture
  • sudo add-apt-repository ppa:graphics-drivers/ppa - Add a PPA to pull new packages
  • sudo apt-add-repository --remove ppa:graphics-drivers/ppa - Remove a PPA
  • apt-rdepends -r python3-pip - Show recursive dependency listings of the package
  • cat /proc/cpuinfo | egrep "(flags|model name|vendor)" | sort | uniq -c - Get CPU flag detection
  • mount -o remount rw / - Remount / path with read-write access
  • echo 'USER_NAME ALL=(ALL:ALL) ALL' | sudo EDITOR='tee -a' visudo - Add a user to visudo/suderos
  • echo 'USER_NAME ALL=NOPASSWD: ALL' | sudo EDITOR='tee -a' visudo - Add password free user
  • id -g USER_NAME - Get primary group id for a user
  • id -gn USER_NAME - Get primary group name for a user
  • usermod -g GROUP_NAME USER_NAME - Change group for a user
  • sudo find /path/to/search -group GROUP_NAME -d type d - Find out folders belong to a specific group
  • Find and kill a process by name
PID=$(ps -ef | grep <process_name> awk '{print $2}')
kill -9 $PID
  • sudo fc-cache -f -v - Update font cache
  • gsettings list-recursively - List settings
  • Auto-mount sdcard/usb
gsettings set org.gnome.desktop.media-handling automount true
gsettings set org.gnome.desktop.media-handling automount false
  • Remove a package from ubuntu
dpkg --list # Find package name
sudo apt remove <package.name> # Remove package

Loop devices

  • Create a disk for FAT type
dd if=/dev/zero of=fat.bin bs=1M count=6
mkfs.vfat ramdisk.bin
mkdir fat
sudo mount -o loop fat.bin fat/
sudo cp <list of files> fat/
sudo umount fat
  • Mount ext4 dd image
sudo losetup -f   # Find out next free loop

sudo dd if=/dev/zero of=ext4.bin bs=1M count=50
sudo losetup /dev/loop0 ext4.bin
sudo mkfs.ext4 /dev/loop0

mkdir -p ext4
sudo mount -t ext4 /dev/loop0 ext4
  • Shrinking disk image (using gparted)
sudo losetup -f                 # Find out next free loop
sudo losetup /dev/loop<0> diskimage.img
sudo partprobe /dev/loop<0>     # Get available partitions
sudo gparted /dev/loop<0>       # Use gparted to manipulate partition
sudo losetup -d /dev/loop<0>    # Unload device
  • Shrinking disk image (using gparted)
fdisk -lu diskimage.img         # Get details of partitions
Disk diskimage.img: 4096 MB, 4096000000 bytes, 8000000 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x000a1bc7

      Device Boot      Start         End      Blocks   Id  System
diskimage.img           2048     5872026     5869978    b  W95 FAT32

Make note of the number shown under End, now use it in following command:

truncate --size=$[(5872026+1)*512] diskimage.img

rsync commands

  • rsync -av --exclude '*.jpg' --exclude '*.mp4' src/ dst/ - Copy the contents of src into dst

  • rsync -av --exclude '*.jpg' --exclude '*.mp4' src dst/ - Copy src into dst

    • / to the destination does not matter, command will create it if dst folder does not exist

  • rsync -av --remove-source-files --exclude '*.jpg' --exclude '*.mp4' src dst - Copy src into dst and remove copied files from the source

dd commands

  • Dump /dev/sda to /dev/sdb
dd if=/dev/sda of=/dev/sdb
dd if=/dev/sda of=/dev/sdb bs=64k conv=noerror,sync
  • Dump disk to a compressed image
dd if=/dev/sda bs=1k | gzip > disk.gzip
gzip -d -c disk.gzip | dd of=/dev/sda bs=1k
  • Create a 5MB disk image
dd if=/dev/zero of=disk.img bs=1k count=5MB
  • Wipe a disk by writing zeros to it
dd if=/dev/zero of=/dev/sda bs=16M
  • Write random numbers to disk
dd if=/dev/urandom of=/dev/sda bs=16M
  • Send random data to framebuffer device
cat /dev/urandom > /dev/fb0
dd if=/dev/urandom of=/dev/fb0 bs=1024 count=8100

cURL commands

  • curl -i -X POST http://localhost:5500/link -F '[email protected]' - Upload a file

  • curl -i -X POST http://localhost:5500/link -H "Content-Type: application/json" --data '{"key":"value"}' - Send json command

  • curl --data "param1=value1&param2=value2" http://localhost:5500/link - Send data

Find commands

  • Find a file of specific name
find . -type f -name "postgis"
  • Get rid of the Clock skew detected. Your build may be in-complete. Put timestamps on all files equal to current time
find . -exec touch {} \;
  • Change format of the files
for i in `find . -name "*.cc" or -name "*.hpp`; do dos2unix $i; done
for i in `find . -name "*.cc" or -name "*.hpp`; do unix2dos $i; done

  • or -- Use to OR multiple -name flags.

  • Find file(s) with a specific name (with loop and custom command)

for i in `find . -name ".mk"`; do echo $i; done
for i in `find . -name ".mk"`; do git add -f $i; done
  • File file(s) of specific extension (Show full path path of the found file)
for i in `find . -name "*.cc"`; do echo $i; done
  • File file(s) of specific extension (Show only file name)
for i in `find . -name "*.cc"`; do echo $(basename $i); done

NOTE: basename is part of the POSIX spec so hoping it is supported by underlying OS otherwise

for i in `find . -name "*.cc"`; do echo ${i##*/}; done
  • File file(s) of specific extension (Show only dir name)
for i in `find . -name "*.cc"`; do echo $(dirname $i); done

NOTE: dirname is part of the POSIX spec so hoping it is supported by underlying OS otherwise

for i in `find . -name "*.cc"`; do echo ${i%/*}; done
  • File file(s) of specific extension (Show file with full path but without .ext)
for i in `find . -name "*.cc"`; do echo ${i%.cc}; done
  • Rename files of specific extensions
for i in `find . -name "*.cc"`; do mv $i ${i%.cc}.cc; done
  • Find all files
find /usr/share/ -type f -printf "%f\n" | sort > all.txt
find /usr/share/ -type f -printf "%f\n" | sort | uniq > uniq.txt
  • Find all sym links in a directory
find . -type l -ls
  • Find and delete empty folders
find /path/to/folder -depth -type d -empty -delete
  • Find and delete specific format file
find . ! -name '*.pdf' -type f -exec rm -f {} +

Redirection

  • 1 denotes stdout; 2 denotes stderr.
  • > - Redirect output of the command onto the right side (Overwrite the contents of output.txt)
  • >> - Redirect output of the command onto the right side (Append to the contents of output.txt)
  • command > output.txt - Redirect standard output stream to output.txt
  • command 2> output.txt - Redirect error stream to output.txt
  • command &> output.txt - Redirect both (standard & error) streams to output.txt
  • command > output.txt 2>&1 - Redirect standard output to output.txt and also redirect error stream to standard output stream
  • command | tee output.txt - Copy standard output stream to output.txt
  • command | tee -a output.txt - Copy & append standard output stream to output.txt
  • command |& tee output.txt - Copy both (standard & error) streams to output.txt

Network

  • Enable eth0
udhcpc -i eth0
route add default gw xxx.xxx.xxx.xx eth0
  • OR -
netcfg eth0 up
netcfg eth0 dhcp
  • OR -
ifconfig eth0 up
ifconfig eth0 down
dhclient eth0

auto eth0
iface eth0 inet dhcp
  • Show IP address assigned to eth0
ifconfig eth0 | grep 'inet addr:' | cut -d: -f2 | awk '{ print $1}'
  • Show network connection
route | grep -m1 ^default | awk '{print $NF}'
  • Network sockets usage
netstat -ltnp | grep -w ':80'
lsof -i :80
netstat -ano -p tcp
sudo netstat -ap | grep 5000

Pandoc

  • Convert word document to markup (Images in the document will be saved to folder # media)
pandoc --extract-media ./media -f docx -t markdown word.docx -o markup.md

VSCode

  • Export installed extensions and install back
code --list-extensions > extensions.list
cat vscode-extensions.list | xargs -L 1 code --install-extension

PDF Manipulation

  • Remove a page from the pdf
gs -sDEVICE=pdfwrite -dNOPAUSE -dBATCH -dSAFER \
  -sPageList=1-3,6- \
  -sOutputFile=out.pdf in.pdf
  • Split the range of pages from the pdf
gs -sDEVICE=pdfwrite -dNOPAUSE -dBATCH -dSAFER \
   -dFirstPage=22393 -dLastPage=23052 \
   -sOutputFile=input.pdf \
   output.pdf
  • Search text in pdf
find docs/ '*.pdf' -exec sh -c 'pdftotext "{}" - | grep --with-filename --label="{}" --color "SwapDrawableWithDamage"' \;
pdftotext my.pdf - | grep 'pattern'
  • Reduce pdf file size
convert -density 200x200 -quality 60 -compress jpeg input.pdf output.pdf

https://askubuntu.com/a/469255

  • Convert png to PDFs
convert img1.png img2.png              -compress jpeg -quality 50 output.pdf
convert img1.png img2.png sample-*.png -compress jpeg -quality 50 output.pdf

Audio Manipulation

  • Handy commands to manipulate audio files.

Swap audio channels

https://trac.ffmpeg.org/wiki/AudioChannelManipulation

Extract audio track

  • Audio track as aac
ffmpeg -i input.mp4 -vn -acodec copy audio.aac
  • Audio track as mp3
ffmpeg -i input.mp4 -vn -f mp3 output.mp3

Audio track + picture = video

  • Convert mp3 file to audio with a picture
ffmpeg -loop 1 -i picture.jpg -i input_audio.mp3 -shortest -c:v libx264 -tune stillimage -c:a copy video.mp4

Change audio sample_fmt

for i in `find . -name "*.wav"`; do echo $(basename $i); ffmpeg -i $i -sample_fmt s16 modify_$(basename $i); done

Duplicate left channel

for i in `find . -name "*.wav"`; do echo $(basename $i); ffmpeg -i $i -sample_fmt s16 -filter_complex "channelmap=map=FL-FL|FL-FR:channel_layout=stereo" modify_$(basename $i); done

Duplicate right channel

for i in `find . -name "*.wav"`; do echo $(basename $i); ffmpeg -i $i -sample_fmt s16 -filter_complex "channelmap=map=FR-FL|FR-FR:channel_layout=stereo" modify_$(basename $i); done

wav files into c

for i in `find . -name "*.wav"`; do echo $(basename $i); xxd -i $(basename $i) > $(basename $i).c; done

Reduce audio file size

ffmpeg -i old.mp3 -acodec libmp3lame -ac 2 -ab 64k -ar 44100 new-1.mp3

Video Manipulation

Convert MOV into MP4

  • MOV into MP4: ffmpeg -i input.mov -codec copy output.mp4
  • Convert codec from HEVC to H264: ffmpeg -i input.mp4 -c:v libx264 output.mp4

Change speed of the video

ffmpeg -i input.mp4 -vf "setpts=speed_multiplier*PTS" output.mp4
  • To slow down your video, you have to use a multiplier greater than 1.
ffmpeg -i input.mp4 -vf "setpts=PTS/factor" output.mp4

Merge two MP4 files

ffmpeg -i concat:"input1.mp4|input2.mp4" output.mp4

Mute the video

ffmpeg -i input.mp4 -an output.mp4

Rotate a video

ffmpeg -i input.mp4 -vf transpose=1 output.mp4

Reduce video size

  • Change quality of the video
ffmpeg -i input.mp4 -c:v libx264 -crf 18 -c:a copy output.mp4
  • Change the resolution & bit rate
ffmpeg -i input.mp4 -s 320x240 -b:v 512k -vcodec mpeg1video -acodec copy output.mp4
  • Change the resolution
ffmpeg -i input.mp4 -vf "scale=iw/2:ih/2" output.mp4
  • Clip the video
ffmpeg -i input.mp4 -c copy -ss 00:03:22.0 -to 00:08:49.0 output.mp4

Embed subtitles

ffmpeg -i input.mp4 -vf "subtitles=lyrics.srt:force_style='FontName=DejaVu Serif,FontSize=24'" output.mp4

Image Manipulation

Convert JPG to PNG

for file in *.jpg; do convert "${file%%.*}".jpg "${file%%.*}".png; done

Convert PNG to RGB565

ffmpeg -vcodec png -i test1.png -vcodec rawvideo -f rawvideo -pix_fmt rgb565 test1.data

Convert RAW data image format to PNG

ffmpeg -f rawvideo -pixel_format rgba -video_size 1920x1080 -i input.data test.png

Convert Planner RGB data image to PNG

convert -depth 8 -interlace plane -size 100x100 rgb:input.data output.png

NOTE: ffmpeg got a complicated command.

Convert PNG image to YUV format

ffmpeg -i test.png -pix_fmt nv12 test.yuv

Convert video to PNG

ffmpeg -i input.mp4 output_%02d.png

  • -r 1.0 - in above command will ask to capture frame after 1 seconds instead of all.

  • Output one image every 1 seconds: ffmpeg -i input.mp4 -vf fps=1 out%d.png

  • Output one image every minute: ffmpeg -i test.mp4 -vf fps=1/60 thumb%04d.png

  • Output one image every 10 minutes: ffmpeg -i test.mp4 -vf fps=1/600 thumb%04d.png

Convert PNGs to video

  • Single image to video of 1 minute length and specific video format
ffmpeg -loop 1 -i test.png -vf format=yuv420p -r 60 -t 60 output.mp4
  • Multiple images to a video
ffmpeg -framerate 60 -i image-%02d.png -vf format=yuv420poutput.mp4
  • Input png are named: input_01.png input_02.png ... input_10.png
  • output.mp4 will have frame rate of 25fps
  • Each image will be shown for 1/25
ffmpeg -framerate 1/5 -i image-%02d.png -vf format=yuv420p output.mp4
ffmpeg -framerate 1/5 -i input_%02d.png -vf format=yuv420p -r 60 test.mp4
  • Show each input image for at least 5 seconds

Darken the images

  • B & W image
for i in `find . -name "*.jpg"`; do convert $i -normalize -threshold 80% $i; done

NOTE: If file name is having spaces, $i will not have full file name. To avoid this

IFS=$'\n'; for i in `find . -name "*.jpg"`; do echo "$i"; done
  • Enhance color image
for i in `find . -name "*.jpg"`; do convert $i -channel RGB -contrast-stretch 1x1% $i; done

https://legacy.imagemagick.org/Usage/color_mods/

PNGs to GIF

convert -delay 25 -loop 0 *.png test.gif