The leftmost column of the directory listing shows the file’s mode. Mode is the term used to refer to a file’s permissions. ls displays the file’s type and mode together as a grouping of ten one-character fields:
| Type | Owner | Group | World | – | rwx | rw- | r– |
User
u user (owner)
g group
o other (world)
a all (user, group, and other)
Operation
+ add
– remove
= set exactly
Mode
r read
w write
x execute
X conditionally set execute
s Set UID or set GID
t set “sticky” bit
For more information: https://www.linuxjournal.com/article/1190
