Command note chmod, umask

Command note chmod, umask
Change the chmod format: chmod [who] [+ 1-1 =] [mode] fileName parameter: who = u, g o, a mode: +-= permission alphanumeric combination: R-4 W-2 X-1 r-x-5 r --- 4 -- X-1 # chmod u = rwx, g = r --, o = r -- 123.txt# chmod 744 123.txt# ls-l 123.txt-rwxr -- r -- 1 root 12777 December 4 20:31 123.txt add or delete a permission to the file # chmod u-x, g + w, o -- 123.txt# ls-l 123.txt-rw-r -- 1 root 12777 December 4 20:31 123.txt chmod-R xyz filname-R indicates cascade change of root user directory permission 755 by default, default File Permission 644 umask specifies the default file or directory permission to view umask values. Enter umask and press Enter. The default value is 0022, And the directory permission is 755, the File Permission is 644all directories in Linux must have the x permission. 0022 Generally, only the last three 022 = ----w-Note: users do not have the x permission to create common files, that is, 666, directory permission is fully open that is 777755 rwx-----w-= rwx r-x r-x644 rw-------w-= rw- r --