CS155: VIM and Regular Expressions Lecture 5

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CS155 VIM and Regular ExpressionsLecture 5
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Review

• NFS allows us to access files on many machines
  transparently.
• Permissions control various types of access to
  files and directories.
• pico is a simple text editor with little
  functionality.

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VIM Visual Editor Improved

• VIM is an advanced editor that has a very large
  number of useful editing features.
• The three basic modes in VIM
• Command mode,
• e.g., when you first enter vi, or press escape
• Insert mode,
• e.g., when you type one of the following iIaAoO
• Line mode or Colon mode
• from command mode, start typing with
• In insert mode text can be entered and modified.
  In command mode commands are given to VIM.

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VIM Switching Modes

• On startup VIM is in command mode.
• To enter insert mode we can use several commands
• i insert at cursor position
• I insert at beginning of line (capital i)
• a insert after cursor position
• A insert at end of line
• o new line below (lower-case o)
• O new line above (upper-case O)
• To exit insert mode use Esc.

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VIM Command Mode

• In command mode typing takes us to line mode
  and allows us to enter a number of VIMs
  commands.
• w write file (save)
• q quit VIM (only if file is saved)
• q! force quit and dont save
• wq save and quit
• We can save the file were editing under a
  different file name by typing w filename

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Navigating in VIM

• In Insert mode we can navigate with the arrow
  keys.
• In command mode we can use the arrow keys plus
  some other useful keys.
• b, w back a word, forward a word
• , - goto beginning of line, goto end of line
• nG goto line n
• G goto end of file
• In line mode we can move to a different line
  number
• 12 - goes to line 12

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Basic Cut and Paste

• To delete the current line type dd in command
  mode.
• To delete a character x
• To delete an word dw or de
• To delete to end of line d
• To paste the deleted text use p

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Basic Command Structure

• Many commands in VIM have the structure n
  command object
• 5w move forward five words
• 5dw delete five words
• 10d delete to end of line and 9 more lines
• 2p paste deleted text twice
• 12x delete twelve characters

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Undo and Redo

• To undo a change, enter command mode and type u
• To redo your undo type R (Ctrl-R) or redo
• The undo list only goes back to the last save.

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Searching for Text

• To search for a string or pattern enter command
  mode and type /pattern
• To search for next match type /
• Search and replace can be carried out by
• s/pattern/replace/cig

Lines to search
Replace all instances on line. (global replace)
Ignore Case
Confirm
Deciphering lines to search all lines in
file . the current line the end of
the file ., from current line to the end of
the file 15,20 lines 15 through 20
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Search and Replace Examples

• s/hello/goodbye/cg search for hello and
  replace with goodbye on all lines in th efile,
  confirm all changes
• 1,10s/good/bye/ig search lines 1-10 for good
  and replace with bye. Ignore the case of good
• .,s/hi/hello/ - search from current line to end
  for hi and replace with hello

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More Details

• For specifying lines to search
• Numbers 1,10
• . current line
• last line
• ,- line number plus or minus some amount
• .5, five lines from cursor to end of file
• -9, last nine lines

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Windows in VIM

• W n split screen horizontally
• W v split screen vertically
• W q close current window
• W arrow move to different window
• e open a file

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Regular Expressions A Brief Introduction

• Often we want to search for a pattern rather than
  a string.
• Regular expressions allow us to specify certain
  types of pattern.
• . match any single character (except \n)
• - match zero or more of the preceeding
  character
• - match only at beginning of line
• - match only at end of line
• match any character in

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Regular Expressions Examples

• s/hello/Hello/ - search for hello at end of
  line and replace with Hello
• s/hmellow//g search for hello,mello,mel
  low, hellow and replace with nothing (delete)
• 1,10s/Goodbye/Hello/ - search for Goodbye at
  beginning of line and replace with Hello