panel 1:

There are 3 things you can do to a file.

read write execute

panel 2:

Is -1 file.txt shows you permissions. Here’s how to interpret the output:
rw- bork (user) can read & write
rw- staff (group) can read & write
r– ANYONE can read

panel 3: File permissions are 12 bits

First digit: setuid
Second digit: setgid
Third digit: sticky

User 110 rwx
Group 110 rwx
all 100 rwx

For files:
r = can read
W = can write
X = can execute

For directories, it’s approximately:
r = can list files
W = can create files
x = can cd into & access files

panel 4:

110 in binary is 6

so rw- = 110 = 6
r– = 100 = 4
r– = 100 = 4

chmod 644 file.txt|
means change the permissions to: rw- r– r–

Simple!

panel 5:

setuid affects executables
$1s-1/bin/ping

rws r-x r-x root root
the s means ping always runs as root

setgid does 3 different unrelated things for executables, directories, and regular files.

person: unix! why??
unix: it’s a long story