This page is part of the course work for CS360: Systems Tools course offered by the Computer Science Department at CalState, San Bernardino, California, USA. It was generated by Dr. Dick Botting.

• cs360/notes/33.ed+ex and also awk
• Why
• Sections
• Facts
• Definitions
• Edit Actions and Symbols
• See also
• Awk
• Questions
• Submit Your Notes Here

cs360/notes/33.ed+ex and also awk

Why

You have to use an editor to make 'vi' and 'emacs' work sometimes. And if they don't work.... what's left?

Sheer unadulterated power: Editting 40 files with a single command.

The rush of Extreme Editing:-)

To program a repetitive action on a file.

Sections


(why): 33.01 33.02
(exam): 33.03 33.04 33.05
(useful): 33.02 33.03 33.04 33.05 33.07
(PostIt Note): 33.03 33.04 33.11
(perhaps): 33.06 33.08 33.12
(skip): 33.09 33.10
(wrong):

Facts

I use ed, ex, and awk all the time -- mainly inside scripts.

Even mail and mailx were influened by ed and ex.

Definitions

1. normal_ed_command::= ed file.
2. batch_ed_command::= ed - file <<terminator eoln commands terminator

3. command::= addresses action.
4. action::=following
   • a::action, append.
   • c::action, change.
   • d::action, delete.
   • i::action, insert.
   • m::action, move.
   • p::action, print.
   • q::action, quit.
   • r::action, read.
   • s::action, substitute.
   • t::action, copy.
   • w::action, write.
   • Plus some multiple character commands
5. addresses::= empty | address | address, address | whole_file_indicator | global_edit.
6. global_edit::= g/ pattern /.
7. address::= simple_address | relative_address | simple_address plus_or_minus number.
8. relative_address::= + number | - number | + | - .
9. simple_address::= before_top | last_line | current_line | marked_line | next_line_to_match | previous_line_to_match.
10. before_top::= 0.
11. last_line::= $.
12. current_line::= period.
13. marked_line::= ' letter.
14. next_line_to_match::= / pattern /.
15. previous_line_to_match::= ? pattern ?.
16. whole_file_indicator::= %

17. normal_string_delimeter::= /.

    Edit Actions and Symbols

18. append::= a lines.
19. change::= c lines.
20. delete::= d.
21. edit::= e force_it_option other_file_symbol | e force_it_option file_name.
22. other_file_symbol::= #.
23. insert::= i lines.
24. move::= m address.
25. print::= p.
26. quit::= q.
27. read::= r source.
28. source::= file_name | ! unix_command.
29. substitute::= s / old_string / new_string / flags.
30. flags::= any of g(global) + c(confirm) + p(print result).
31. old_string::=pattern | empty.
32. new_string::=any string of characters but escape special chars like & and /. copy.
33. write::= w force_it_option append_it_option destination_option.
34. force_it_option::= empty | ! .
35. append_it_option::= empty | >>.
36. destination_option::= empty | file_name.
37. Symbols::=following
    • dollar::ed_symbol= $ , last_line.
    • percent::ex_symbol=%, whole_file_indicator.
    • plus::ex_symbol=+, relative_address.
    • minus::ex_symbol= - , relative_address.
    • single_quote::ex_symbol=' , marked_line.
    • period::ed_symbol= . , current_line.
    • g::ed_symbol, global_edit.
    • slash::ed_symbol = / , search for next_line_to_match and normal_string_delimeter.
    • question_mark::ed_symbol = ? , search for previous_line_to_match.
    • exclamation_mark::ed_symbol = ! , force_it_option.

38. pattern::= See http://www.csci.csusb.edu/dick/cs360/notes/26.patterns.html
39. pattern::= See http://www.csci.csusb.edu/dick/cs360/notes/26.patterns.html
40. file_name::==http://www.csci.csusb.edu/dick/cs360/notes/18.files.html#filename
41. file_name::==http://www.csci.csusb.edu/dick/cs360/notes/18.files.html#filename

42. number::=decimal number.
43. letter::= a..z.
44. empty::=

45. TBA::=To Be Answered.

    See also

    An example of using ed to set up the notes for this class.... I needed to move the "Questions" section to the end of the notes and did it with an 'ed' script //www/dick/cs360/notes/fix.ed //www/dick/cs360/notes/fix.ed

    As another example, I was asked how to put a line in front of a file (its easy to add a line at the end with

     		echo line >>file

    ) but how to prepend a line into file. Answer the [ prepend ] script. You call it like this:

     		prepend file_name line to put in front of file

    Awk

    Awk is both useful and on the final exam, See
46. awk::= See http://www.csci.csusb.edu/dick/cs360/notes/awk.html
47. awk::= See http://www.csci.csusb.edu/dick/cs360/notes/awk.html

    Questions

    Answer the following questions about the 'ed' editor:
    • What does a '$' mean in front of a command ?
    • What does a '$' meaan in a search string ?
    • What two symbols go around search strings and patterns in ed/ex/vi/sed/awk ?
    • What does /abc/s/xyz/012/ do ?
    • what does g/123/s///g do ?
    • What does +5 do ?
    • What does /QUESTION/,+5p do ?
    • What does e! do ?
    [ Questions in awk ] [ Questions in awk ]

    Submit Your Notes Here

    To earn credit for completing this part of the course you need to send me a short list of things you have learned. A simple way to do this is to follow this [click here if you can fill this hole] link and fill in the form.