Add ImageMagick and file transfer tutorial
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@ -34,7 +34,7 @@ opportunity to learn about computers, files, directories and programs.
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* [[./tutorial/files_directories.org][Learning about files and directories]]
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* [[./tutorial/rsync.org][Using rsync to copy files]]
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* [[./tutorial/search_files.org][Searching for files in the system]]
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* [[./tutorial/diff.org][Comparing two files or directories: 'diff']]
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* [[./tutorial/diff.org][Comparing two files or directories: 'diff']]
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* [[./tutorial/diff_patch.org][Comparing two files and create a unified version: diff and patch]]
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* [[./tutorial/dd_command_flash_usb.org][Using dd command to flash usb]]
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* [[./tutorial/compress_pdf.org][Compress a pdf file]]
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@ -42,10 +42,14 @@ opportunity to learn about computers, files, directories and programs.
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* [[./tutorial/pacman.org][Use package manager in Parabola GNU-linux: verify packages in cache]]
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* [[./tutorial/removing_packages.org][Removing packages in Parabola GNU-Linux]]
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** Secure shell ssh and file transfer
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* [[./tutorial/copy_server.org][Transfering files between machines]]
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** Work with images
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* [[./tutorial/image_size_reduction.org][Reduce image quality and size from terminal]]
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** Disk space utilization and manipulation
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* [[./tutorial/ncdu.org][Exploring disk space with 'ncdu']]
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@ -0,0 +1,64 @@
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#+date: 2023-08-20
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#+options: toc:nil num:nil author:nil
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* Transfering files
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Let's say you want to transfer files, images or directories between a local
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machine and a server. What could be a good option?
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There are multiple free software options to transfer file between machines:
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* [[https://wiki.archlinux.org/title/Rsync][rsync]]
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* [[https://man.archlinux.org/man/sftp.1.en][sftp]] (secury file transfer protocol)
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* [[https://wiki.archlinux.org/title/SCP_and_SFTP][scp]] (secure copy protocol)
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** rsync
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For example: transfering all the ~.jpg~ files in the directory to a server:
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#+begin_example sh
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rsync -a -P -e "ssh -p 2222" ./*.jpg root@186.76.90.145:/root/img/
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#+end_example
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** scp
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** Using ~sftp~ to copy files
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~sftp~ can be used to transfer files from a local machine to a server. The
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protocol allows to access the server, visualize, manipulate and transfer
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files from and to a server. You need to configure ~ssh~ access to the
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server from your local machine.
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A server can be accessed from a local machine following this logic:
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#+begin_example sh
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sftp -P 2222 root@186.76.90.145
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#+end_example
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The command ~sftp~ followed by the port and user@ip_address.
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After accessing the server, files can be download from the server:
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#+begin_example sh
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sftp> get file_in_server
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#+end_example
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You can also transfer files to the server:
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#+begin_example sh
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sftp> put file_in_local_machine
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#+end_example
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To exit from ~sftp~ use:
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#+begin_example sh
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sftp> put file_in_local_machine
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#+end_example
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There are additional options to use ~sftp~. Check the manual to know more about:
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#+begin_example sh
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info sftp
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#+end_example
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** References
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@ -3,14 +3,32 @@
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* Use imagemagick to manipulate images
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[[https://imagemagick.org/][ImageMagick]] is a suite of tools used for digital image edition and manipulation.
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The tools can be used in the command line (~cli~).
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There are multiple functionalities avaliable in ImageMagick. Commands like ~convert~,
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~mogrify~ and ~identify~ are just some of the useful tools available.
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** Using the ~convert~ command
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Converting multiple ~jpg~ files into lower size images:
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First, [][cd] into the directory containing all the images
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#+begin_example sh
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cd directory
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#+end_example
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Then use ~convert~ to resize all the 'jpg' files within the directory:
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#+begin_example sh
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convert '*.jpg' -set filename:fn '%[basename]-small' -resize 960x640 '%[filename:fn].jpg'
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#+end_example
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convert <INPUT_FILE> -quality 10% <OUTPUT_FILE>
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Here the '%[basename]-small' will copy original files, resize and rename including
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the suffix "small" to the original name.
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Reduce quality using convert (the command is similar to the previous one, but
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it uses ~-quality~ instead of ~-resize~)
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#+begin_example sh
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convert '*.jpg' -set filename:fn '%[basename]-small' -quality 50% '%[filename:fn].jpg'
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@ -18,17 +36,29 @@ convert <INPUT_FILE> -quality 10% <OUTPUT_FILE>
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** Using mogrify
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~mogrofy~ can be used for similar purposes.
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Let's check som images in a directory to verify how much those images can be
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modified.
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Change directory use the commands in the same place were the images are included,
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e.g:
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#+begin_example sh
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cd directory
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#+end_example
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Counting number of ~.jpg~ images in a directory:
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#+begin_example sh
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ls -1U DIR_NAME | wc -l
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#+end_example
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Output:
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Verify the output:
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75
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75
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Verifying the images weight:
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Verifying the images weight of all the images:
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#+begin_example sh
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du -h
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@ -48,6 +78,8 @@ Output:
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42M
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Reduce the quality of all the images within the directory:
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#+begin_example sh
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mogrify -quality 80% *.jpg
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#+end_example
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@ -62,9 +94,54 @@ Output:
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12M
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** Remove some metada from images
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[[https://imagemagick.org/script/command-line-options.php#strip][`mogrify -strip`]]can be used to remove some metada from the images.
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First you can check the image metada using the command ~identify~ from Imagemagick.
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#+begin_example sh
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identify -verbose image.jpg
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#+end_example
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This command will print an output like this:
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# Filename: image.jpg
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# Permissions: rw-r--r--
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# Format: JPEG (Joint Photographic Experts Group JFIF format)
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# Mime type: image/jpeg
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# Class: DirectClass
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# Geometry: 960x640+0+0
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# Resolution: 72x72
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# Print size: 13.3333x8.88889
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# Units: PixelsPerInch
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# Colorspace: sRGB
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# Type: TrueColor
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# Base type: Undefined
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# Endianness: Undefined
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# Depth: 8-bit
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# Channels: 3.0
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# Channel depth:
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# Red: 8-bit
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# Green: 8-bit
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# Blue: 8-bit
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# Channel statistics:
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# Pixels: 614400
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# ...
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# ...
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# Version: ImageMagick 7.1.1-12 Q16-HDRI x86_64 21239 https://imagemagick.org
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You can use ~mogrify~ to remove metada from one or multiple images using
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something like:
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#+begin_example sh
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mogrify -strip ./image.jpg # one image
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mogrify -strip ./*.jpg # modifiyng all 'jpg' files in directory
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#+end_example
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** References
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- [[https://askubuntu.com/questions/1354205/imagemagick-convert-on-a-multiple-files][Imagemagick to convert multiple files]]
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- [[https://imagemagick.org/][Imagemagick web site]]
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- [[https://www.digitalocean.com/community/tutorials/reduce-file-size-of-images-linux][Digital ocean tutorial]]
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