Draft

Print how long the current user has been connected in hours

 * ac

Calculate the result of an expression and force the number of decimal places to 10

 * bc <<< "scale=10; 5 / 3"

Calculate the result of an expression with sine and cosine using mathlib

 * bc -l <<< "s(1) + c(1)"

Recursively copy a directory's contents to another location (if the destination exists, the directory is copied inside it)

 * cp -R path/to/source_directory path/to/target_directory

Make a bootable USB drive from an isohybrid file (such like archlinux-xxx.iso) and show the progress

 * dd if=file.iso of=/dev/usb_drive status=progress

Generate a system backup into an IMG file and show the progress

 * dd if=/dev/drive_device of=path/to/file.img status=progress

Restore a drive from an IMG file and show the progress

 * dd if=path/to/file.img of=/dev/drive_device status=progress

List the human-readable size of all .jpg files in subdirectories of the current directory, and show a cumulative total at the end

 * du -ch */*.jpg

Extract pages from a PDF file

 * gs -dQUIET -dBATCH -dNOPAUSE -sDEVICE=pdfwrite -sOutputFile=output.pdf input.pdf

Merge PDF files

 * gs -dQUIET -dBATCH -dNOPAUSE -sDEVICE=pdfwrite -sOutputFile=output.pdf input1.pdf input2.pdf

To view a file

 * gs -dQUIET -dBATCH file.pdf

List all processes of the current user as a tree

 * ps --user $(id -u) f

Sort processes by memory consumption

 * ps --sort size

Strip out non-printable characters from a file

 * tr -cd "[ === print === ]" < filename