Command: file oriented command

• cd
• pwd
• ls
• cp
• rm
• mv
• mkdir <-> rmdir
• more / less
• diff / cmp
• wc
• sort
• uniq
• head
• tail
• du
• df

File premission

• basic permission
  • r – read                              4
  • w – write                           2
  • x – execute/ search        1
  • – – no premission          0
• permission categories
  • u – user
  • g – group
  • o – global/other
• show it by ls -l

change permission of a file:

• chmod  (category)+/-(permission) filename
  • 7 = 4 + 2 + 1 = give all premission
  • 6 = 4 + 2 = read and write
  • 5 = 4 + 1 = read and execute
  • 3 = 2 + 1 = write and execute
  • chmod 777 -> give full permission to all categories

change ownership of file: chgrp

change owner of file: chown

file command: determine file type of a ordinary file

Pattern matching file name:

• * any number of any character
• ? any one character
• [] a set of character

DOS to UNIX

• change file between OS
  • unix2dos / dos2unix
  • tr ‘\r’ ‘\n’
  • mtools on tuxworld

/dev/null

• infinite sink
• infinite source of end-of-file
• use
  • discarding output
  • terminating input