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"Ghostscript is preinstalled on a lot of Linux systems and can quite easily be used to merge and optimize multiple PDF files into one.
[shuser]
gs -q -sDEVICE=pdfwrite -dPDFSETTINGS=/prepress -o merged.pdf <first>.pdf <second>.pdf[/shuser]
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.
Install the package extra/rebuild-detector
It will create a pacman hook to check which packages need to be rebuild, but can also be executed with the following command.
[shuser]
checkrebuild[/shuser]
The packages might be rebuilt automatically a lot of the time, but sometimes it is necessary to for a rebuild using the AUR helper.
This is an example using paru
[shuser]
paru -S --rebuild=yes <package>[/shuser]
Use faillock to check for failed sudo attempts
[shroot]
faillock --user <user>[/shroot]
Unlock a locked account
[shroot]
faillock --user <user> --reset[/shroot]
Unlock user after too many failed sudo attempts by Josh Sherman
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
column -t -s, < {FILE.CSV}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/DIRFirst, the USB device you want to check has to be selected
[shuser]
lsusb
(out)Bus 004 Device 001: ID 1d6b:0003 Linux Foundation 3.0 root hub
(out)Bus 003 Device 003: ID 0c45:652f Microdia Backlit Gaming Keyboard
(out)Bus 003 Device 002: ID 046d:c084 Logitech, Inc. G203 Gaming Mouse
(out)Bus 003 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub
(out)Bus 002 Device 002: ID 0781:55a3 SanDisk Corp. SanDisk 3.2Gen1
(out)Bus 002 Device 001: ID 1d6b:0003 Linux Foundation 3.0 root hub
(out)Bus 001 Device 002: ID 2972:0047 FiiO Electronics Technology FiiO BTR5
(out)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
(out)bcdUSB 3.20[/shuser]
Using touch it is possible to change the timestamps on a file.
Note: The file has to be owned by the user executing the command
Example changing the access and modify timestamps:
[shuser]
touch -a -m -t 202307291506.07 <file>[/shuser]
-a: accessed time
-m: modified time
-t: timestamp - [[CC]YY]MMDDhhmm[.ss] time formatAlternatively to -t it is also possible to use -d for a looser format.
ISO8061 obviously works as well.
[shuser]
touch -a -m -d "2 hours ago" <file>
touch -a -m -d "2023-07-29T00:23" <file>[/shuser]
Linux - modify file modify/access/change time
How can I change the date modified/created of a file?
Using mktemp, a randomly named file or directory will be created in /tmp
Create a file:
[shuser]
mktemp[/shuser]
Create a directory:
[shuser]
mktemp -d[/shuser]
Save the output into an environment variable for future referencing
sh / Bash:
[shuser]
export TMPDIR=$(mktemp -d)[/shuser]
Fish:
[shuser]
set TMPDIR (mktemp -d)[/shuser]