wiki-grav/pages/04.other/useful-commands/default.en.md

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Imagemagick

Splitting PDF files

convert -density 600 {INPUT.PDF} -crop 50x100% +repage {OUT.PDF}

-density: adjusts the quality of the resulting pdf. Higher values look better, but take longer to process
-crop 50x100%: this splits the pdf into "left" and "right". 100x50% would split into "top" and "bottom"

Find

Change filtered permissions

Using find with its exec switch one can set different permissions based on the usual find filters.
One example would be only changing file or directory permissions.

find (directory) -type f -exec chmod 744 {} +

Replacing -type f with -type d would execute the chmod for directories instead.

Various

Overwrite disk with pseudorandom data

Using openssl on CPUs with AES acceleration one can create pseudorandom data with high speeds.
Much faster than /dev/urandom at least

openssl enc -aes-128-ctr -md sha512 -pbkdf2 -nosalt -pass file:/dev/urandom < /dev/zero | pv > {TARGET DISK}

Around 2GiB/s on my Ryzen 7 1700x if output to /dev/null

Formatted csv in terminal

From Pretty CSV viewing on the Command Line

column -t -s, < {FILE.CSV}

Download directory from webdav

Using wget, it's possible to download directories recursively from WebDAV.

wget -r -nH -np --cut-dirs=1 --user={USERNAME} --password={PASSWORD} https://WEBDAVHOST/DIR/DIR

Find USB speed in use

First, the USB device you want to check has to be selected

[shuser]

lsusb
Bus 004 Device 001: ID 1d6b:0003 Linux Foundation 3.0 root hub
Bus 003 Device 003: ID 0c45:652f Microdia Backlit Gaming Keyboard
Bus 003 Device 002: ID 046d:c084 Logitech, Inc. G203 Gaming Mouse
Bus 003 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub
Bus 002 Device 002: ID 0781:55a3 SanDisk Corp.  SanDisk 3.2Gen1
Bus 002 Device 001: ID 1d6b:0003 Linux Foundation 3.0 root hub
Bus 001 Device 002: ID 2972:0047 FiiO Electronics Technology FiiO BTR5
Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub

[/shuser]

Now, using the ID, the USB class used can be determined

[shuser]

lsusb -d 0781:55a3 -v | grep bcdUSB
bcdUSB               3.20

[/shuser]