every process has command line arguments

$ ls 1 /usr/bin
(ls, -l, and usr are arguments!)

they’re passed to the program as an array

example from Python:

import sys 
print(sys.argv)

['test.py', 'file.txt' ]

arguments can be any sequence of bytes

$ python program.py ♥
(emoji are totally allowed!)

the first argument is the executable’s name

[
'ls'
'-1',
'/usr/bin/'
]

(ls is the executable name)

the total length of the arguments is limited

you can find the limits on your system with xargs -show-limits
It’s usually ~2MB

you can decide how you parse arguments

• -flag: single dash!
• --flag: 2 dashes!
• ♥♥flag: weird emoji scheme that will be very annoying to use!