13. less & more
• less/more!
• less line move,more page move!
• does not read the entire input file before starting!
• less -N line-number!
• ls /etc | less
14. tail & head
• tail !
• tail -f!
• tail -5!
!
• head!
• head -5
26. " chmod – Change a file's mode!
" umask – Set the default file permissions!
" su – Run a shell as another user!
" sudo – Execute a command as another user!
" chown – Change a file's owner
29. umask
• umask!
• the default permissions of created file!
• octal notation !
• express a mask of bits to be removed from a file's
mode attributes!
• common default value: 022 002