editing 102 eds big brother ex

1
Chapter 6

• editing 102 eds big brother ex

2
The Origins of ex

• Bill Joy hated (hates?) the ed editor
• He and Chuck Haley were using the em (editor for
  mortals) editor
• Joy started working on em
• first built en (editor new)
• evolved through several iterations
• ended up with ex

3
How ex is like ed

• Its a line editor
• It has two modes
• command
• text entry
• They share many of the same commands
• Both use buffers to hold data to be edited

4
Differences between ed and ex

• Joy thinks ex is more user friendly
• ed has two buffers ex has the following
• editing, undo, and anonymous buffers
• 26 named buffers
• ex commands can be full words
• cant change the command mode prompt
• ex has a full screen mode (vi)

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Starting ex

• The ed editor has several command line options
• -r (recover from an editor crash)
• -R (read only)
• -s (suppress normal standard output messages)
• -v (start in visual mode) This is the same as
  using the vi command
• -x or -C (encrypt the file being edited)

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General command formataddress1,address2
command argument(s) option(s)

• No address the command works on the current line
• one address the command works on that line
• two addresses the command works on that range
• the range must be positive and start at or after
  the first line of the buffer
• the range must end at or before the last line of
  the buffer

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Addressing modes in ex

• . the current line
• last line in the file
• n the nth line in the file
• c the line marked c
• n or n- line above or below n
• -5 or 5 5 lines above or below current line

• n-m or nm m lines above or below line n
• /pat/ search forward for next line containing pat
• ?pat? like / but search backwards
• all the lines in the buffer (very useful!)

8
Error Messages

• Longer than eds
• Thought to be more useful than eds

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Bidding ex Adieu

• Cant quit without saving the buffer with q must
  use q!
• Can temporarily suspend ex with sus or st

10
Saving your work

• write is most common way to write buffer
  changes to disk
• wq asks ex to write then quit
• xit asks ex to write if the buffer has been
  changed, and then quit. This is the most
  efficient way to exit while saving your work.

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Finding or Changing the Associated File Name

• File lets you see the associated file
• file also allows you to change the file
  associated with the buffer

12
Displaying the Contents of a File

• The display tools look like eds
• l (ell) show lines with special characters
• nu show lines and line numbers Note difference
  from eds command n.
• p show lines unadorned
• commands also have a count option instead of a
  range of lines in the address

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Displaying the Contents of a File (cont.)

• The display commands also take a flags option
• act line nu and put out line numbers
• l show non-printing characters line l (ell) does
• p display the lines as they were typed with no
  special characters

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Adding Text to a File

• Append a acts like append in ed
• append appends after the line specified
• Insert i acts like insert in ed
• insert inserts before the line specified
• Change c used to replace one or more lines
• enter a . (dot) as the only character to go to
  command mode

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Deleting a Line From a File

• Delete d deletes lines, use substitute to delete
  words
• can put deleted text in anonymous (the default)
  buffer or a named buffer
• can put text from any of the buffers back into
  editing buffer to perform a cut and paste
• if you use change to delete, the lines are lost

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Buffers

• Joy built two types of buffers into ex
• anonymous buffer (the unnamed buffer where
  deleted or yanked lines are tucked away)
• named buffers (a - z) which hold the deleted text
  until replaced

17
Putting Lines Back

• The put p command takes the contents of the
  anonymous buffer (by default) or a named buffer
  and places it after the line specified

18
Copying Lines

• The copy co command duplicates one or more lines
  after the line specified.
• If you want several copies consider yanking and
  putting rather than copying.

19
Yanking lines

• The yank y command copies one or more lines to
  the anonymous or named buffer.
• Lines that are yanked remain in the buffer
  unchanged.
• You need to put the yanked lines back into the
  buffer (with the put command).

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Moving Lines

• The move m command moves a line from one place to
  another in the buffer.
• It is faster to move a line than to delete and
  put it in most cases
• You can move a line or range of lines only one
  time (since it isnt there anymore!)

21
Combining Lines

• The join j command works like eds join
• However it is a little smarter, it adds spaces if
  necessary!
• Bang (!) prevents adding spaces

22
Substitution, Your Best Friend

• As with ed, substitute allows you to change parts
  of a line.

23
Global

• The global g command acts like a super range
  designator
• can use different characters to enclose the
  search string
• the v version finds lines that dont match the
  pattern

24
Using Shell Commands

• Precede the shell command with a bang (!)
• can capture the output in the editing buffer if
  you precede the bang with a line number

25
Reading other files

• The read r command reads another file into the
  editing buffer, combining two files.
• If you dont specify a file name, read will read
  the file associated with the buffer!
• Useful to
• put in a standard heading
• put in a standard footer

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Editing Other Files

• If you want to edit other files while still in ex
  you can
• next n to read in the next file from the list of
  files on the command line
• edit e to read a new file you specify (not from
  the command line)

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Oops

• To reverse the last change to the buffer, use the
  undo u command
• Substantial differences between vi and vim!
• In vi the undo undoes up to the last write
• In vim the undo undoes the last change to the
  buffer

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Marking and Returning to Places in a File

• The mark ma command marks a place in the buffer.
• You can put 26 marks in a buffer (a - z)
• The tick mark () sends control to the marked
  line.
• j would send control to the line marked j
• Marks exist only for an editing session they are
  not preserved with the file.

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Setting Options for the Ex Editor

• There are a number of options you can set to make
  your life easier
• Use the set se command to set these options
• autoindent ai keeps the same level of indention
• number nu numbers the lines
• tabstop ts sets the tab width default 8, 4 works
• terse shortens some error messages

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Other ex commands

• There are a number of lesser used commands that
  may be handy
• chdir change the current working directory
• preserve grab a copy of the buffer just as if
  the editor crashed
• recover a file from an editing crash
• gt shift the line(s) specified shiftwidth right
• lt shift the line(s) specified shiftwidth left

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Other ex commands (cont.)

• shell drop out to the command line to perform
  some task
• when you finish, type exit to return to ex
• source execute a series of ex commands stored
  in a file. You can also store commands in a
  buffer and execute them from that buffer!
• Open go to vi for one command.
• visual switch from command line to visual (vi)
  mode.