Week 2 notes

Concepts

Superblock/Inode tables - There is a hidden database for Unix filesytems made up of entries called inodes. These inodes contain all the information about a file that Unix needs.

Symbolic link - A special file that points to another file that may or may not exist. ln -s original_file pointer is used.

Commands

Text viewer/editor commands

• cat - concatenate/view files
• tail - read end of file
• head - read beginning of file
• more - read file with scrolling
• less - less is more
• vi - available everywhere, fast text editor
• emacs - very powerful and complex editor

vi

Vi has two modes editing mode and command prompt(ex mode.)

You are in editing mode by default. To add text you can press the a or i keys. To leave append or insert editing mode press the [esc] key.

In editing mode (when not using the a,o or r text inserting mode) these are some of the more useful commands you can use...

• e - skip to end of next word
• x - delete a character
• dd - delete line (save to buffer)
• yy - copy to buffer without deleting
• p - paste buffer contents on following line
• / - find pattern in text
• : - enter command prompt

At the command prompt ":" found at the lower left hand corner of the screen you can use these (and many other) commands. To return to editing mode hit [esc]

• q! - quit vi without saving
• wq - write and quit
• wq! - write read-only file overwriting permissions
• w filename - write to a different filename
• vi filename - edit new file
• set ruler - continuously display current coordinates
• linenumber p - paste buffer at linenumber
• linenumber,linenumber2 y - copy lines linenumber to linenumber2 into buffer
• linenumber,linenumber2s/old_pattern/new_pattern/g - search for old_pattern and replace with new_pattern between lines linenumber and linenumber2