Add chmod notes

Software Notes/linux/chmod.txt

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+Symbolic mode:
+chmod who-+=permission filename
+"who-+=permission" section can be repeated for different combos with a comma ,
+
+who:
+u - user
+g - group
+o - other
+a - all
+
+permissions:
+r - read
+w - write
+x - execute
+X - execute only if the file is a directory or already has execute permission for some user
+s - set user or group ID on execution (????)
+t - sticky bit (????)
+
+chmod u=rwx,g=rx,o-rwx filename
+
+
+
+Number mode
+chmod user_permission..group_permission..other_permission filename
+0 <= permission <= 7
+
+permissions:
+>>> for i in range (8):
+...     print(i, bin(i))
+... 
+0 0b000
+1 0b001
+2 0b010
+3 0b011
+4 0b100
+5 0b101
+6 0b110
+7 0b111
+n __rwx
+
+chmod 754 filename
+binary breakdown:
+chmod 111 101 100 filename