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1.1 root 1: .\" @(#)e2 6.1 (Berkeley) 5/22/86
2: .\"
3: .SH
4: Writing text out as a file \- the Write command ``w''
5: .PP
6: It's likely that you'll want to save your text for later use.
7: To write out the contents of the buffer onto a file,
8: use the
9: .ul
10: write
11: command
12: .P1
13: w
14: .P2
15: followed by the filename you want to write on.
16: This will copy the buffer's contents
17: onto the specified file
18: (destroying any previous information on the file).
19: To save
20: the text on a file named
21: .UL junk ,
22: for example, type
23: .P1
24: w junk
25: .P2
26: Leave a space between
27: .UL w
28: and the file name.
29: .ul
30: Ed
31: will respond by printing
32: the number of characters it wrote out.
33: In this case,
34: .ul
35: ed
36: would respond with
37: .P1
38: 68
39: .P2
40: (Remember that blanks and the return character at the end of each
41: line are included in the character count.)
42: Writing a file just makes a copy of the text \- the
43: buffer's contents are not disturbed, so you can go on adding
44: lines to it.
45: This is an important point.
46: .ul
47: Ed
48: at all times works on a copy
49: of a file, not the file itself.
50: No change in the contents
51: of a file takes place until you give a
52: .UL w
53: command.
54: (Writing out the text onto a file from time to time as it is being
55: created is a good idea, since if the system crashes or if you make some horrible mistake, you will lose
56: all the text in the buffer but any text that was written onto
57: a file is relatively safe.)
58: .SH
59: Leaving ed \- the Quit command ``q''
60: .PP
61: To terminate a session with
62: .IT ed ,
63: save the text you're working on
64: by writing it onto a file using the
65: .UL w
66: command,
67: and then type the command
68: .P1
69: q
70: .P2
71: which
72: stands for
73: .IT quit .
74: The system will respond with
75: the prompt character
76: .UL $ "" (
77: or
78: .UL % ).
79: At
80: this point your buffer vanishes, with all its text,
81: which is why you want to write it out before quitting.\(dg
82: .FS
83: \(dg Actually,
84: .IT ed
85: will print
86: .UL ?
87: if you try to quit without writing.
88: At that point, write if you want;
89: if not, another
90: .UL q
91: will get you out regardless.
92: .FE
93: .SH
94: Exercise 1:
95: .PP
96: Enter
97: .ul
98: ed
99: and
100: create some text using
101: .P1
102: a
103: \&. . . text . . .
104: \&\fB.\fR
105: .P2
106: Write it out using
107: .UL w .
108: Then leave
109: .ul
110: ed
111: with the
112: .UL q
113: command, and print the file,
114: to see that everything worked.
115: (To print a file, say
116: .P1
117: pr filename
118: .P2
119: or
120: .P1
121: cat filename
122: .P2
123: in response to
124: the prompt character.
125: Try both.)
126: .SH
127: Reading text from a file \- the Edit command ``e''
128: .PP
129: A common way to get text into the buffer is to read it
130: from a file in the file system.
131: This is what you do to edit text
132: that you saved with the
133: .UL w
134: command in a previous session.
135: The
136: .ul
137: edit
138: command
139: .UL e
140: fetches the entire contents of a file into the buffer.
141: So if you had saved the three lines
142: ``Now is the time'', etc.,
143: with a
144: .UL w
145: command in an earlier session,
146: the
147: .ul
148: ed
149: command
150: .P1
151: e junk
152: .P2
153: would fetch the entire contents of the file
154: .UL junk
155: into the buffer, and respond
156: .P1
157: 68
158: .P2
159: which is the number of characters in
160: .UL junk .
161: .ul
162: If anything was already in the buffer, it is deleted first.
163: .PP
164: If you use the
165: .UL e
166: command to read a file into the buffer,
167: then you need not use a file name after a subsequent
168: .UL w
169: command;
170: .ul
171: ed
172: remembers the last file name used in an
173: .UL e
174: command,
175: and
176: .UL w
177: will write on this file.
178: Thus a good way to operate is
179: .P1
180: ed
181: e file
182: [editing session]
183: w
184: q
185: .P2
186: This way, you can simply say
187: .UL w
188: from time to time,
189: and be secure in the knowledge that
190: if you got the file name right at the beginning,
191: you are writing into the proper file each time.
192: .PP
193: You can find out at any time what file name
194: .ul
195: ed
196: is remembering by typing the
197: .ul
198: file
199: command
200: .UL f .
201: In this example,
202: if you typed
203: .P1
204: f
205: .P2
206: .ul
207: ed
208: would reply
209: .P1
210: junk
211: .P2
212: .SH
213: Reading text from a file \- the Read command ``r''
214: .PP
215: Sometimes you want to read a file into the buffer
216: without destroying anything that is already there.
217: This is done by the
218: .ul
219: read
220: command
221: .UL r .
222: The command
223: .P1
224: r junk
225: .P2
226: will read the file
227: .UL junk
228: into the buffer;
229: it adds it
230: to the end of whatever is already in the buffer.
231: So if you do a read after
232: an edit:
233: .P1
234: e junk
235: r junk
236: .P2
237: the buffer will contain
238: .ul
239: two
240: copies of the text (six lines).
241: .P1
242: Now is the time
243: for all good men
244: to come to the aid of their party.
245: Now is the time
246: for all good men
247: to come to the aid of their party.
248: .P2
249: Like the
250: .UL w
251: and
252: .UL e
253: commands,
254: .UL r
255: prints
256: the
257: number of characters read in, after the reading operation is complete.
258: .PP
259: Generally speaking,
260: .UL r
261: is much less used than
262: .UL e .
263: .SH
264: Exercise 2:
265: .PP
266: Experiment with the
267: .UL e
268: command \-
269: try reading and printing various files.
270: You may get an error
271: .UL ?name ,
272: where
273: .UL name
274: is the name of a file;
275: this means that the file doesn't exist,
276: typically because you spelled the file name wrong,
277: or perhaps that you are not allowed to read or write it.
278: Try alternately reading and appending to see that they work
279: similarly.
280: Verify that
281: .P1
282: ed filename
283: .P2
284: is exactly equivalent to
285: .P1
286: ed
287: e filename
288: .P2
289: What does
290: .P1
291: f filename
292: .P2
293: do?
294: .SH
295: Printing the contents of the buffer \- the Print command ``p''
296: .PP
297: To
298: .ul
299: print
300: or list the contents of the buffer (or parts
301: of it) on the terminal, use the print command
302: .P1
303: p
304: .P2
305: The way this is done is as follows.
306: Specify the lines where
307: you want printing to begin and where you want it to end,
308: separated by a comma, and
309: followed by the letter
310: .UL p .
311: Thus to print the first two lines of the buffer, for
312: example, (that is, lines 1 through 2) say
313: .P1
314: 1,2p (starting line=1, ending line=2 p)
315: .P2
316: .ul
317: Ed
318: will respond with
319: .P1
320: Now is the time
321: for all good men
322: .P2
323: .PP
324: Suppose you want to print
325: .ul
326: all
327: the lines in the buffer.
328: You could use
329: .UL 1,3p
330: as above if you knew there were exactly
331: 3 lines in the buffer.
332: But in general, you don't
333: know how many there are, so what do you use for the ending
334: line number?
335: .ul
336: Ed
337: provides a shorthand symbol for ``line number of
338: last line in buffer'' \- the dollar sign
339: .UL $ .
340: Use it this
341: way:
342: .P1
343: 1,$p
344: .P2
345: This will print
346: .ul
347: all
348: the lines in the buffer (line 1 to last line.)
349: If you want to stop the printing before it is finished,
350: push the
351: .UC DEL
352: or Delete key;
353: .ul
354: ed
355: will type
356: .P1
357: ?
358: .P2
359: and wait for the next command.
360: .PP
361: To print the
362: .ul
363: last
364: line of the buffer, you could use
365: .P1
366: $,$p
367: .P2
368: but
369: .ul
370: ed
371: lets you abbreviate this to
372: .P1
373: $p
374: .P2
375: You can print any single line by typing the line
376: number followed by a
377: .UL p .
378: Thus
379: .P1
380: 1p
381: .P2
382: produces the response
383: .P1
384: Now is the time
385: .P2
386: which is the first line of the buffer.
387: .PP
388: In fact,
389: .ul
390: ed
391: lets you abbreviate even further:
392: you can print any single line by typing
393: .ul
394: just
395: the line number \- no need to type the letter
396: .UL p .
397: So if you say
398: .P1
399: $
400: .P2
401: .ul
402: ed
403: will print the last line of the buffer.
404: .PP
405: You can also use
406: .UL $
407: in combinations like
408: .P1
409: $\-1,$p
410: .P2
411: which prints the last two lines of the buffer.
412: This helps when you want to see how far you got in typing.
413: .SH
414: Exercise 3:
415: .PP
416: As before, create some text using the
417: .UL a
418: command and
419: experiment with the
420: .UL p
421: command.
422: You will find, for example,
423: that you can't print line 0 or a line beyond
424: the end of the buffer, and that attempts
425: to print a buffer in reverse order by saying
426: .P1
427: 3,1p
428: .P2
429: don't work.
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